Epigenomes doi: 10.3390/epigenomes10020032

Authors: Anna Chiara Conflitti Fani Konstantinidou Alessandra Buonacquisto Gaia Cicolani Enrico Delli Paoli Silvia Di Chiano Antonella Linari Ludovico Muzii Serena Bianchini Federica Quaranta Francesco Pallotti Francesco Lombardo Liborio Stuppia Valentina Gatta Donatella Paoli

Background/Objectives: Aberrant DNA methylation of imprinted genes and increased sperm DNA fragmentation (SDF) have been implicated in male infertility. However, their impact on assisted reproductive technology (ART) outcomes remains unclear. This pilot study aimed to investigate SDF and methylation status of H19, IGF2, and PEG1/MEST in relation to fertilisation and embryo development following intracytoplasmic sperm injection (ICSI). Methods: Twenty male partners of women undergoing ICSI were recruited and classified according to ART outcome into viable embryos (VEs, n = 7), non-viable embryos (NVEs, n = 7), and no fertilisation (NF, n = 6). Before sperm selection, an aliquot of each seminal sample was used for semen analysis according to WHO, 2021, SDF assessment (TUNEL assay), and sperm DNA methylation analysis of H19, IGF2, and PEG1/MEST (pyrosequencing). Results: Semen parameters were above the fifth percentile. SDF was significantly lower in the VE group compared with the other groups. H19 CpG1 methylation correlated positively with viable embryos (p = 0.016), while H19 CpG2 island showed a positive correlation with sperm concentration (p = 0.028). In male/couple infertility cases, total H19 methylation correlated negatively with SDF (p = 0.050). IGF2 CpG3 island methylation correlated positively with viable embryos (p = 0.027). Total PEG1/MEST methylation was positively correlated with fertilisation events (p = 0.002) and viable embryos (p = 0.011). PEG1/MEST CpG2 island also positively correlated with sperm motility (p = 0.034), while CpG3 and CpG4 showed significant correlations with fertilisation (p < 0.001; p = 0.004). Conclusions: This pilot study shows that SDF and sperm methylation levels of H19, IGF2, and PEG1/MEST are related to ICSI outcomes, supporting that sperm molecular and epigenetic features may influence fertilisation and embryo development.

Epigenomes doi: 10.3390/epigenomes10020031

Authors: Chitrakshi Chopra Chandra Prakash Prasad Manish Kumar

The ubiquitously transcribed tetratricopeptide repeat Y-linked gene (UTY/KDM6C), a catalytically impaired histone demethylase encoded on the Y chromosome, has garnered increasing attention for its emerging roles in tumorigenesis and cancer progression. Despite high sequence homology with its X-linked paralog UTX/KDM6A, UTY exhibits markedly reduced or absent H3K27me3 demethylase activity due to critical amino acid substitutions in its Jumonji C domain. Consequently, UTY primarily functions through non-enzymatic mechanisms, acting as a scaffold in chromatin-remodelling complexes like COMPASS and SWI/SNF, or mediating protein–protein interactions that regulate transcriptional programs independent of demethylation. This aligns with epigenetic dysregulation in cancers, where imbalances in repressive H3K27me3 and active H3K4me either drive tumour suppressor silencing or oncogene activation. Unlike frequently mutated UTX in cancers such as breast, renal cell carcinoma, and acute myeloid leukaemia, UTY’s contributions in cancer are less defined, constrained by male-specific expression. Emerging evidence suggests UTY as a context-dependent tumour suppressor in AML and squamous-like pancreatic ductal adenocarcinoma. While direct functional validation remains limited in several cancer types, UTY is increasingly implicated as a potential tumour suppressor in haematological malignancies and prostate cancer. Therapeutically targeting UTY’s scaffold functions shows promise for male-specific cancers and merits future investigation.

Epigenomes doi: 10.3390/epigenomes10020030

Authors: Su Chen Yunsung Lee Siri E. Håberg Per Magnus Christian Magnus Page Emese H. C. Kovács Anne L. Dunlop Alicia K. Smith John W. Holloway Syed Hasan Arshad Wilfried Karmaus Susan L. Ewart

Background/Objectives: Parity, the number of times a woman carries a pregnancy to viability, has been linked to long-term maternal health outcomes. The mechanisms linking parity to health outcomes are poorly understood but may reflect influences of pregnancy on the maternal epigenome. Methods: This study examines the relationship between parity and DNA methylation (DNAm) during pregnancy using data from three cohorts: the Norwegian Mother, Father and Child Cohort Study (MoBa), the Atlanta African American Maternal-Child (AAAMC) cohort, and the Isle of Wight (IOW) Birth Cohort. Results: An epigenome-wide association study (EWAS) in MoBa identified 5374 cytosine–phosphate–guanine sites (CpGs) that were statistically significantly associated with parity, of which 69% were positively and 31% negatively correlated. Replication analyses confirmed 3491 CpGs in at least one cohort, and 93 CpGs in both AAAMC and IOW. Gene enrichment analysis revealed significant involvement of developmental and signaling pathways, including calcium signaling and neuroactive ligand–receptor interaction. Additionally, 584 differentially methylated regions (DMRs) were detected, with 90% overlapping individual parity-related CpGs. Conclusions: These findings suggest that parity influences epigenetic patterns, potentially affecting biological processes and molecular functions relevant to maternal health later in life.

Epigenomes doi: 10.3390/epigenomes10020029

Authors: Orna Levran Justin Li Anat Sason Miriam Adelson Einat Peles

Background/Objectives: Opioid use disorder (OUD) is caused by a complex interplay between genetic and non-genetic factors. DNA methylation is an epigenetic mechanism that modulates gene expression. Data on DNA methylation and opioid addiction and treatment are limited. This association study was designed to assess the difference in genome-wide methylation patterns between individuals with OUD in methadone maintenance treatment (MMT) (n = 114) and those with OUD who achieved long-term abstinence (>10 years) without mu opioid receptor agonist treatment (n = 136). Methods: Differential DNA methylation analysis was performed in whole blood using the Illumina EPIC array. Results: A total of 135 differentially methylated probes (DMPs) reached epigenome-wide significance (p < 1 × 10−7), controlling for sex, age, estimates of blood cell proportions, and the first two principal components based on genome-wide SNP genotypes. The methylation sites were annotated to 157 genes, including 32% long non-coding RNAs. These genes are related to several systems, including cell adhesion (e.g., SAXO4), immune system and inflammation (e.g., UBTF, USP39, C10orf90, PRKCA), stress response (e.g., CRHR1, GPR19), and spermatogenesis (e.g., SPATA16, COX7B2). DMP cg11641410 is located in lncRNA ENSG00000254687, an antisense to OPRK1. Six of the DMPs were also identified in a related longitudinal study of MMT. Conclusions: At this point, it is not possible to determine whether the minor methylation differences observed in this study cause clinically relevant changes in gene expression. However, these findings have the potential to identify biomarkers and to provide new targets for treatment optimization.

Epigenomes doi: 10.3390/epigenomes10020028

Authors: Rosalyn E. Acevedo Esther Walton Karen R. Mifsud

Hyaluronan (HA) is a ubiquitous extracellular matrix (ECM) component that is gaining significant attention for its diverse roles in cell signalling and disease. The biological functions of HA are dependent on its molecular weight (Mw): low Mw polysaccharide chains drive stimulatory processes such as inflammation and angiogenesis, whereas high Mw HA is stabilising and anti-inflammatory. Growing evidence indicates that HA is integral to brain function. The composition of HA in the brain is regulated by the balance of enzymatic synthesis and degradation, mediated by different isoforms of hyaluronan synthase (HAS) and hyaluronidase (HYAL) respectively. Fluctuating expression of the genes encoding the HAS and HYAL enzymes has been implicated in neuropathology and ageing, with some studies providing evidence towards epigenetic regulation of these genes. The regulatory environment of the brain confers a unique balance of enhanced protection alongside the requirement for maximum flexibility. This scoping review focuses on summarising current knowledge regarding epigenetic regulation of HAS and HYAL genes in neural contexts, as well as identifying gaps in knowledge against which future research can be directed. Understanding how these genes are regulated, particularly through epigenetic mechanisms, provides insight into how HA is regulated in the brain, facilitating understanding regarding its function in brain health and disease.

Epigenomes doi: 10.3390/epigenomes10020027

Authors: Fernando Bergez-Hernández Martín Irigoyen-Arredondo Lizeth Carolina Flores-Méndez Alejandra Paola Martínez-Camberos

Background: Aging is the strongest risk factor for prostate cancer (PCa). It is accompanied by progressive epigenomic divergence, known as epigenetic drift, particularly affecting DNA methylation at regulatory regions. However, the extent to which age-associated promoter methylation contributes to coordinated microRNA (miRNA) expression changes in PCa remains incompletely characterized. Methods: We conducted an integrative in silico analysis of 449 primary tumors from the TCGA-PRAD cohort. Age was modeled as a continuous variable. Age-related miRNA expression changes were estimated from miRNA-seq data using DESeq2. Promoter DNA methylation changes (±2 kb from transcription start sites) were assessed using Illumina 450K arrays and linear regression. MiRNAs showing significant age-associated alterations at both expression and methylation levels were classified as concordant or discordant based on directionality and prioritized using an effect size-based concordance score. We analyzed experimentally validated targets of prioritized miRNAs through functional enrichment and network-based approaches to identify convergent regulatory pathways. Results: Initially, we identified 105 age-associated miRNAs. After filtering, 65 candidates remained. Of these, we found 37 miRNAs with significant age-associated changes at both layers, including 20 concordant and 17 discordant miRNAs. These comprised well-characterized cancer-associated miRNAs and lesser-studied candidates enriched in CpG-rich regulatory regions. Network analyses revealed a limited set of genes under convergent regulation by multiple age-associated miRNAs. These implicated pathways are related to cell cycle control, apoptosis, stress response, and epigenetic regulation. Conclusions: Our findings support a model in which age-dependent promoter methylation drift contributes to coordinated miRNA deregulation in PCa. This convergence highlights biologically plausible miRNA biomarkers and age-sensitive epigenetic circuits relevant to prostate carcinogenesis.

Epigenomes doi: 10.3390/epigenomes10020026

Authors: Abdelhamid Bouramtane Badreddine Elmakhzen Amal Ouskri Mohamed Ahakoud Laila Bouguenouch Karim Ouldim Omar Askander

Background: Parental imprinting plays a crucial role in epigenetic regulation and is increasingly recognized for its involvement in neurodevelopmental disorders. Although ATP8A2 is considered a non-imprinted gene; However, the marked phenotypic variability observed across related disorders suggests that additional regulatory layers may influence its expression. Methods: We investigated the imprinting-like status of ATP8A2 through functional analyses of a splicing variant (c.1580-3C>G) identified in a patient diagnosed with Cerebellar Ataxia, Mental Retardation, and Disequilibrium syndrome type 4 (CAMRQ4). Sanger sequencing was used to assess allelic expression and identify aberrant transcripts. Results: Our analyses revealed an allelic expression imbalance suggestive of parental imprinting of ATP8A2. Moreover, Sanger sequencing led to the identification of a novel ATP8A2–RAB3GAP2 chimeric transcript, pointing to a previously unreported transcriptional event, the functional relevance of which remains to be determined. Conclusions: These findings indicate that ATP8A2 may be subject to imprinting-like regulation and involved in atypical splicing events with unknown significance. This highlights the need for further investigation into the epigenetic and transcriptional complexity of ATP8A2-related neurodevelopmental disorders.

Epigenomes doi: 10.3390/epigenomes10020025

Authors: Andrea Stoccoro Carmela Serpe Antonia Parmeggiani Vincenzo Davide Catania Mario Lima Alessandro Ghezzo Cristina Panisi Marida Angotti Beatrice Pranzetti Provvidenza Maria Abruzzo Cinzia Zucchini Lucia Migliore Marina Marini Fabio Coppedè

Background/Objectives: Although the etiopathogenesis of autism spectrum disorder (ASD) remains incompletely elucidated, current evidence supports a multifactorial model involving genetic and environmental factors that interact to induce a heterogeneous range of symptoms. In recent years, epigenetic mechanisms, particularly DNA methylation, have been recognized as key contributors to ASD pathophysiology. Alterations in mitochondrial DNA (mtDNA) methylation are also emerging as relevant contributors in several human conditions. The mitochondrial D-loop, a non-coding control region essential for mtDNA replication and transcription, is considered a hotspot for epigenetic regulation and its methylation levels have been found altered in various diseases, such as cancer, metabolic disorders, and neurological illness. However, to date, no studies have investigated mtDNA methylation changes in ASD. Methods: We analyzed the average methylation levels of a fragment containing ten CpG sites within the D-loop region and the mtDNA copy number in peripheral blood samples from 49 children with ASD and 50 neurotypically developing (NT) controls using Methylation-Sensitive High-Resolution Melting and quantitative PCR. Results: No significant differences in D-loop methylation levels were observed between ASD and NT children. Similarly, the mtDNA copy number did not differ between the two groups. No significant correlations were found between D-loop methylation or mtDNA copy number and either ASD severity or age. Conclusions: This is the first study investigating mtDNA methylation in ASD. Our results indicate that methylation of the D-loop region and the mtDNA copy number are not altered in ASD children. Further studies including larger cohorts and extended mtDNA regions are warranted to confirm and expand these findings.

Epigenomes doi: 10.3390/epigenomes10020024

Authors: Stanislav E. Romanov Dmitry E. Koryakov

The conserved protein SetDB1 has been identified in various vertebrate and invertebrate groups. It plays key roles in vital processes such as germline and nervous system development, immune response, tumorigenesis, cell cycle progression, and others. SetDB1 is initially characterized as an enzyme that methylates lysine 9 on histone H3, leading to gene silencing, which is traditionally considered its primary function. However, SetDB1 also targets about a dozen nuclear, cytoplasmic, and membrane proteins as substrates. Moreover, some functions of SetDB1 do not require methyltransferase activity. Due to its SUMO-interacting motif, Tudor domain, and methyl-binding domains, SetDB1 interacts with a wide range of complexes that regulate protein stability and activity, signal transduction pathways, and chromatin spatial organization. In this review, we aim to expand the classical view of SetDB1 as solely a histone methyltransferase and to highlight the broader diversity of its functions.

Epigenomes doi: 10.3390/epigenomes10020023

Authors: Mélida del Rosario Lizarazo-Taborda Julio César Villegas-Pineda Holver Parada Fabian Galvis Javier Soto

Epithelial ovarian carcinoma (EOC) is the most common type of ovarian cancer and represents the most lethal gynecologic neoplasm. EOC is usually diagnosed at late stages due to its nonspecific signs and symptoms. Although significant clinical advances have been made in other types of malignancies, EOC remains a disease that requires further biological research to identify new therapeutic targets or new treatment alternatives, as conventional approaches are often ineffective or lead to the development of resistance and unwanted side effects. There are a significant number of natural products from which commercially available drugs have been derived, largely for the treatment of cancer, but none of them focus on epigenetic changes in specific targets in EOC. Based on the above, this work focuses on describing the in vitro and in vivo findings from the last twelve years derived from the action of important phytochemicals on epigenetic targets in ovarian cancer, among other mechanisms of action, revealing that there is a significant gap to be bridged in terms of the transition from basic to applied research regarding the potential of plant-derived molecules as possible epidrugs in EOC.

Epigenomes doi: 10.3390/epigenomes10020022

Authors: Nien-yu Yang Yicong Huang Chaewon Park Te-Min Ke Graham Tilston George Manias Dimosthenis Kyriazis Jon Young Susan Hart Graham Fulford Artitaya Lophatananon Kenneth R. Muir

Background: Sustaining long-term lifestyle change remains a major challenge in preventive health. Epigenetic clocks offer a dynamic, modifiable measure of biological ageing that may enhance motivation when returned to individuals. Objectives: This study had two aims: (1) to evaluate whether personalised health reports integrating epigenetic age, polygenic cancer risk scores, and lifestyle metrics could motivate sustained behavioural change; and (2) to examine variability across epigenetic clock generations to inform the selection of a suitable model for participant feedback. Methods: A total of 178 adults were recruited via the Graham Fulford Charitable Trust community testing programme, and 91 completed a one-year follow-up survey assessing behavioural, psychological, and knowledge-related outcomes. DNA methylation data from 140 samples were used to compare 14 epigenetic clocks across four generations. Results: Most participants reported positive lifestyle changes, including feeling healthier (72.5%), increased physical activity (60.4%), and improved diet (47.3%). Gains were also observed in health knowledge (63.7%) and psychological well-being (31.9%). Epigenetic clock comparisons revealed substantial heterogeneity across models. Zhang2019-BLUP was selected as a stable and interpretable measure of biological age that can be readily communicated to participants, supporting empowerment and improved health literacy, rather than serving only as a risk prediction metric. Conclusions: Personalised biomarker feedback including epigenetic age combined with lifestyle and wearable data can support self-reported improvements in health-related behaviours. Community-based delivery through trusted local networks proved effective. The marked variation between epigenetic clocks highlights the importance of selecting models designed for clear communication when used in public-facing health interventions.

Epigenomes doi: 10.3390/epigenomes10010021

Authors: Hirofumi Sakuma Satoshi Kawaguchi Yuya Kobayashi Akiko Koizumi Naoki Nakagawa

MicroRNAs (miRNAs) are small non-coding RNAs that play central roles in post-transcriptional gene regulation and cellular homeostasis maintenance. Dysregulation of miRNA expression is increasingly recognized as a key contributor to tissue injury during the acute phase and to disease progression in the chronic phase. Chronic kidney disease (CKD) commonly progresses and ultimately leads to kidney failure through interstitial fibrosis, which is the final common pathway of CKD progression. Interstitial fibrosis is driven not only by fibroblast activation but also by phenotypic transitions in injured tubular epithelial cells, infiltrating macrophages, and peritubular capillary cells. These multifaceted cellular pathways induce and exacerbate interstitial fibrosis, and several miRNAs have been identified as important regulators of these pathways. In addition to fibrotic pathophysiological features, disease-specific dysregulation of miRNAs has been increasingly detected in various causes of CKD, including diabetic kidney disease, chronic glomerulonephritis, and nephrosclerosis. In this review, we provide an integrated overview of miRNA-mediated regulation in CKD, with particular emphasis on cell lineage functions within fibrotic pathways and disease-specific roles. Finally, we discuss the emerging potential of miRNAs as biomarkers and therapeutic targets for CKD and highlight future research directions.

Epigenomes doi: 10.3390/epigenomes10010020

Authors: Kenneth C. Ehrlich Michelle Lacey Sriharsa Pradhan Melanie Ehrlich

Background/Objectives: Genome-wide studies of differential DNA methylation often focus on its role in turning transcription on or off. Here we report some atypical epigenetic/transcription relationships for 92 genes that are highly and preferentially expressed in primary human myoblasts relative to heterologous cell cultures. Methods: We compared methylomes and myoblast-specific differentially methylated regions (DMRs) with methylomes, chromatin profiles, and transcriptomes for many different cell populations. Results: We found that myoblast-associated promoter hypomethylation was unusually prevalent among the 92 myoblast-preferential genes. Sometimes this promoter hypomethylation was seen as a myoblast-associated extension of their constitutively unmethylated region at a CpG island. All 92 genes showed some myoblast-specific hypomethylation, including 32 genes at tissue-specific super-enhancers or broad H3K4-trimethylated promoters. Myoblast hypermethylated DMRs were also associated with almost half of the myoblast-preferential genes. These hypermethylated DMRs were often in intragenic locations embedded in H3K36-trimethylated chromatin in myoblasts. Conclusions: Our analysis suggests that some of the hypermethylated DMRs repress cryptic, alternative, or adjacent promoters. Myoblast hypermethylated DMRs may also downmodulate expression in myoblasts to avoid yet higher RNA levels found in adult or fetal skeletal muscle tissue. The epigenetic insights that were obtained can help elucidate the transcription regulation of some of these genes (e.g., MUSK, RAPSN, HEYL, SYNPO2, SYNPO2L, STAC3, PITX2, and TPPP3) that are implicated in congenital myasthenic syndromes, myasthenia gravis, muscle repair, heart dysfunction, or cancer. This study supports cell type-specific roles for DNA hypo- and hypermethylation as a modulator of transcription levels, in addition to being an on–off switch during differentiation.

Epigenomes doi: 10.3390/epigenomes10010019

Authors: Gareth Pollin Angela J. Mathison Elise N. Leverence Thiago Milech De Assuncao Juan Iovanna Johnny C. Hong Michael T. Zimmermann Raul Urrutia Gwen Lomberk

Background/Objectives: Pancreatic ductal adenocarcinoma (PDAC) arises predominantly from activating KRAS mutations, yet individual genetic variants differ markedly in signaling output and clinical impact. G12D, the most prevalent variant, strongly drives oncogenic programs, whereas G12R signals less efficiently through the AKT and ERK pathways and is associated with longer patient survival than G12D-driven PDAC. Methods: To elucidate how these differences influence early cellular transformation, we expressed a panel of KRAS mutants in non-cancerous pancreatic ductal epithelial cells as a model of early PDAC initiation and profiled transcriptional and phospho-proteomic responses. We next examined whether epigenetic differences translate into mutation-specific changes in nuclear organization using quantitative imaging of G12D- and G12R-expressing nuclei at 24 and 48 h. Results: Each variant established a unique regulatory program enriched for chromatin remodelers, histone modifiers, and nuclear structural factors, indicating that variant-specific KRAS signaling rapidly develops divergent epigenetic states. Integrated transcriptomic and phospho-proteomic analyses identified G12D and G12R as the most divergent variants. G12D induced pronounced nuclear remodeling, including increased nuclear size, irregular morphology, and reorganization of the nucleolus and spliceosome, consistent with extensive chromatin and transcriptional reprogramming. In contrast, G12R elicited a weaker response, with minimal or delayed structural changes. Conclusions: Together, these findings demonstrate that KRAS mutational context in pancreatic ductal epithelial cells shapes early transcriptional reprogramming that actively remodels nuclear architecture and nuclear sub-compartments. This work establishes nuclear structural remodeling as a structural state of KRAS-driven epigenetic dysregulation during PDAC initiation.

Epigenomes doi: 10.3390/epigenomes10010018

Authors: Orna Levran Yuli Kim Justin Li Anat Sason Miriam Adelson Einat Peles

Background/Objectives: Methadone maintenance treatment (MMT) is one of the major pharmacotherapies for opioid use disorder. The underlying mechanisms of addiction and the treatment response are only partially understood. The study’s main goal was to identify differential DNA CpG methylation that occurred in response to MMT. Methods: Toward this goal, we have conducted a longitudinal epigenome-wide study of blood samples from 64 patients at the beginning and after 1–3 years of MMT, using a linear mixed model. Results: A total of 1881 differentially methylated probes (DMPs) were identified (FDR < 0.05), controlling for sex, age, estimates of blood cell proportions, and the first two principal components based on genome-wide SNP genotypes. Among the genes annotated to the top DMPs are DGLUCY, NXNL2, SOX10, and NPAS3. Several genes associated with substance use disorder were annotated by the identified DMPs, including ADORA2A, BDNF, CACNA1D, CREB1, CRHR1, CRY1, DNMT3B, GABRD, GNAS, GRIP1, OXR1, PRKACB, SCN2A, and SCN3A. The most overrepresented pathway is the small GTPase-mediated signal transduction pathway, and the most overrepresented process is the actin cytoskeleton organization. Conclusions: The study provides preliminary insight into the epigenetic effect of MMT. Future studies will have to confirm the DMPs, assess their impact on gene expression, and determine their clinical relevance.

Epigenomes doi: 10.3390/epigenomes10010017

Authors: Dominik Jung Daniel Diehl Anna Hagemann Hagen Sjard Bachmann

Background: Protein prenylation is crucial for the function of hundreds of proteins. Aberrant protein prenylation can be caused by the aberrant expression of prenyltransferases (PTases), which has been reported for multiple cancer entities. The reasons for aberrant PTase expression in cancer have not yet been investigated. Methods: We analyzed CpG methylation within promoter-associated CpG islands of the PTase genes FNTA, FNTB, PGGT1B, and RABGGTA via bisulfite conversion and pyrosequencing to assess its role in PTase expression and gain deeper insight into the regulation of protein prenylation in cancer. We used DNA from three benign controls (whole blood samples, peripheral blood mononuclear cells, and HEK293) and 19 human cancer cell lines from various origins to assess DNA methylation within PTase gene promoter-associated CpG islands. For a subset of these cell lines, we measured mRNA expression via qPCR and correlated it with DNA methylation. Results: Methylation across all PTase genes ranged from 1.9 ± 0.9% to 11.4 ± 4.0% (mean methylation ± standard deviation) in benign cells, and 2.3 ± 1.0% to 16.0 ± 5.4% in cancer cells. DNA methylation and mRNA expression of PGGT1B correlated inversely (PCC = −0.75; p = 0.005). Conclusions: We saw no general differences between benign and malignant cells, but observed significant differences between non-malignant controls and multiple individual cancer cell lines regarding the methylation of PTase genes. This was prominently seen in PGGT1B in Caki-1 cells, raising the possibility that DNA methylation is involved in the dysregulation of PTase expression in cancer.

Epigenomes doi: 10.3390/epigenomes10010016

Authors: Ohbeom Kwon Hyeonwoo La Seonho Yoo Hyeonji Lee Heeji Lee Hoseong Lim Chanhyeok Park Dong Wook Han Jeong-Tae Do Hyuk Song Youngsok Choi Kwonho Hong

R-loops, three-stranded nucleic acid structures formed by an RNA-DNA hybrid, have emerged as important regulators of transcription and genome stability. Although advances in high-throughput sequencing have revealed widespread R-loop landscapes, platform-specific biases hinder the identification of conserved R-loops in specific cell types. Mouse embryonic stem cells, which are transcriptionally active, provide an ideal system for investigating the potential roles of stable R-loops in RNA biology. Here, we integrated 13 independent R-loop profiling datasets from four experimental platforms to define 27,950 Common R-loop regions in mouse embryonic stem cells and characterized their chromatin environment and associated biological functions. Common R-loop regions were reproducibly detected across methods and were preferentially localized to promoter-proximal and genic regions enriched in CpG islands. Genes associated with Common R-loops were highly and stably expressed, showing strong functional enrichment in RNA metabolic processes such as mRNA processing, RNA splicing, and ribonucleoprotein complex biogenesis. Chromatin state analysis revealed that Common R-loops are enriched in transcriptionally active and regulatory contexts. Sequence feature analysis further identified GC skew as a prominent signature of Common R-loops, particularly within transcribed chromatin states. Transcription factor motif analyses have identified distinct regulatory environments in Common R-loop regions, including pluripotency-associated OCT4-SOX2-TCF-NANOG motifs in enhancers, CTCF motifs in open chromatin, and YY1 motifs in promoters. Together, this study provides the first integrated analysis of conserved R-loop regions in mouse embryonic stem cells, revealing their preferential localization at regulatory loci linked to RNA metabolism and highlighting R-loops as structural and functional nodes in RNA biology.

Epigenomes doi: 10.3390/epigenomes10010015

Authors: Anati Alyaa Azhar Hector Mendoza

Cell division is a highly regulated process that actively involves dynamic changes to the genetic material within the nucleus. DNA is faithfully replicated in the S-Phase of the cell cycle, being converted from loose, relaxed chromatin into tight, condensed chromosomes to be segregated in mitosis. In addition to scaffolding proteins that shape these mitotic chromosomes, post-translational modifications of histones within nucleosomes modulate chromosome dynamics throughout the cell cycle. In this review, we use a comparative approach to highlight some of the major epigenetic marks affected by the cell cycle during embryogenesis of Caenorhabditis elegans: H4K20me1, H3S10ph, H4S1ph, H2AS1ph, and H3T118ph. These five histone post-translational modifications will be specifically highlighted in the context of the mitotic cell cycle, as they are well documented in the C. elegans literature.

Epigenomes doi: 10.3390/epigenomes10010014

Authors: Varvara Maksimova Valeriia Popova Alyona Kholodova Julia Makus Olga Usalka Eugenia Lylova Aleksandr Kudriashov Gennady Belitsky Marianna Yakubovskaya Kirill Kirsanov

Background/Objectives: The aberrant epigenetic landscape of cancer cells has attracted wide attention, motivating the search for new epigenetically active drugs both for anticancer therapy and for overcoming the drug resistance promoted by epigenetic changes. The use of epi-drugs in cancer therapy requires consideration of the influence of applied treatment on epigenetic regulation of gene expression. Therefore, it is reasonable to screen epigenetically active compounds among the drugs widely used in clinical oncology. Methods: We applied the HeLa TI cell-based assay to analyze the epigenetic activity of 40 drugs including 22 chemotherapeutic, 2 immunotherapeutic, 13 targeted, and 3 palliative agents. Reactivation of the epigenetically silenced GFP reporter gene integrated into the genome of HeLa TI cells was assessed using flow cytometry. Results: Statistically significant increases in the proportions of GFP-positive cells were demonstrated for the alkylating agent chlorambucil; the antimetabolites cytarabine, fluorouracil, gemcitabine, and pemetrexed; the platinum-based compounds cisplatin, and oxaliplatin; the topoisomerase inhibitor topotecan; and the antimicrotubule agents docetaxel, vincristine, and eribulin. Epigenetic activity was also detected for the targeted-therapy agents AZD8055, wortmannin, and cetuximab, as well as for the corticosteroid dexamethasone. Thus, epigenetic activity was revealed for 15 drugs widely used in cancer therapy, which possess different modes of action. Conclusions: Our findings show that many anticancer therapy agents modulate the epigenetic landscape of cancer cells, providing a rationale for expanding their therapeutic applications and enhancing the efficacy of combination strategies by overcoming epigenetically driven chemoresistance.

Epigenomes doi: 10.3390/epigenomes10010013

Authors: Fabrício Castro Machado Nilmar Silvio Moretti

Chromatin dynamics are usually modulated by histone epigenetic post-translational modifications, which rapidly and reversibly govern accessibility and transcriptional responsiveness. During microbial infection, this regulatory layer becomes a highly contested interface where host defense mechanisms and pathogen-driven subversion strategies converge and compete. Many infectious agents exploit chromatin to reprogram gene expression, creating cellular environments that are conducive to infection, proliferation, and persistence. Diverse strategies have been described for viruses, bacteria, fungi, protozoa and nematodes, including the direct secretion of acetyltransferases and methyltransferases, interference with host chromatin-binding proteins, subcellular localization of transcriptional factors or epigenetic regulators, and metabolic availability manipulation. Concurrently, host cells activate immune and stress-response genes to mount rapid, adaptable antimicrobial responses. Recent advances in genome-wide, single-cell, and spatial omics profiling have begun to reveal the temporal and cell-type-specific dynamics of the host genome at the core of infection. This review synthesizes current insights into how chromatin is rewired by the major categories of pathogens during infection, highlighting representative case studies across infective agents and the functional consequences for immunity and cell fate. In addition, we discuss emerging techniques for epigenomic and transcriptomic data collection, and the potential of targeted host-directed therapeutic strategies. Chromatin regulation is thus a promising field of study and a possible target for next-generation interventions.

Epigenomes doi: 10.3390/epigenomes10010012

Authors: Grace Tavelli Nikki Schultz Joanna Brisbane Nina Kresoje Samantha Lodge Jeremy K. Nicholson Nicola J. Armstrong Desiree Silva Nina D’Vaz David Martino

Background/Objectives: Consumption of a Mediterranean diet (MD) has been associated with reduced incidence of non-communicable diseases and reduced overall mortality, with epigenomic effects representing plausible mediators. The aim of this pilot study was to explore potential epigenetic associations between DNA methylation markers in blood and adherence to an MD in pregnancy. Methods: Fifty-two pregnant women with high or low adherence to an MD throughout pregnancy, who participated in the BioMood ORIGINS study, were selected using an extremes-of-exposure design. DNA methylation (DNAm) profiles from whole blood were generated using the TWIST human methylome panel. We conducted both genome-wide and candidate gene-based differential methylation analyses to identify epigenetic variations between the study groups. Furthermore, we explored potential associations between blood methylation patterns and circulating inflammatory markers (GlycA, GlycB and SPC) previously observed to exhibit differential abundance in the same cohort of women. Results: There were no genome-wide significant differences in methylated dinucleotides between MD groups (p-value < 5 × 10−8); however, a region-based analysis identified 2210 differentially methylated regions (DMRs) (FDR < 0.05, absolute maximum logFC > 1) annotated to 1537 genes, significantly enriched in metabolic, inflammatory and neuronal signaling pathways. Leveraging publicly available data, we replicated nine novel DMR associations. Changes in circulating phospholipid inflammatory markers were significantly associated with a small methylation difference in Lipin-1 (LPIN1), albeit with a small effect size (p-value < 5 × 10−8). A look-up analysis of previously reported MD-associated genes in this cohort detected small but statistically significantly different methylation of CpGs located within collagen type XVIII alpha 1 (COL18A1) and peroxisome proliferator-activated receptor gamma, coactivator 1 beta (PPARGC1B) gene regions. Conclusions: We provide preliminary evidence for modest methylation changes in specific genes associated with adherence to an MD.

Epigenomes doi: 10.3390/epigenomes10010011

Authors: Valentina S. Obrezanenko Polina M. Shulga Anastasia G. Volkova Anastasia A. Primova Yulia A. Remizova Ivan O. Meshkov Alexandra D. Kikot Daria A. Tarasova Ekaterina S. Bolashova Alexey A. Ivashechkin Antonida V. Makhotenko Ekaterina A. Snigir Yulia A. Masyukova Elizaveta I. Radion Olesya A. Kuznetsova Maria S. Cheporova Michail Y. Fedyanin Alexey A. Tryakin Valentin V. Makarov Vladimir S. Yudin Anton A. Keskinov Anna S. Makarova

Background: HML-2 subgroup mobile genetic elements of the HERV-K family were described to participate in carcinogenesis processes, but their expression and epigenetic regulation in molecular subtypes of colorectal cancer (CRC) remain partly characterized. The present study aimed to evaluate the expression of HML-2 elements using RNA-sequencing data in paired tumor and normal intestinal tissue samples from 63 patients with CRC to identify patterns of the retrotransposons’ activity in different molecular subtypes (CMSs). Methods: RNA-sequencing and DNA methylation data were analyzed for paired CRC and normal tissue samples. HERV-K expression was assessed using three bioinformatics tools: Telescope (version 1.0.3), TEtranscripts (version 2.2.3), GeneTEFlow (version 2020). Molecular tumor subtypes were defined using the CMScaller (version 0.99.2) program. The results of the HML-2 loci expression analysis were supplemented with the HML-2 proteins expression data obtained by quantitative RT-PCR. Results: HML-2 expression assessment by GeneTEFlow (version 2020), TECount (version 2.2.3) and Telescope (version 1.0.3) showed high convergence: the Pearson correlation coefficient for each tool exceeded 0.88. Several HML-2 loci were identified as differentially expressed in CRC samples of different CMS. The PCR results confirmed an increase in HML-2 expression in tumor tissues. For all CMSs, an inverse association was detected between differential methylation of CpG sites and differential expression of HML-2 loci. Associations of HML-2 expressions with differentially expressed genes in which they are located were found, and for a number of such genes an inverse relationship between the expression level and the methylation level of their promoters were demonstrated, and data on the involvement in the pathogenesis of CRC were described: CR1, CD48, TTLL3, ABCC2 and ZNF420. Expression signatures associated with the activity of the RIG-I-like receptor signaling cascade were identified in CMS1–3 CRC samples, which may indicate the possible implementation of viral mimicry against the background of HML-2 activation. Conclusions: Analysis of the expression of HML-2 and its association with CpG methylation contributes to a comprehensive interpretation of the CRC pathogenesis mechanisms.

Epigenomes doi: 10.3390/epigenomes10010010

Authors: Andra-Giorgiana Zaruha Patricia Codreanu Mădălin-Codruț Coman Monica Andreea Novac II Simona Gabriela Duță-Ion Ioana Ruxandra Jugănaru Iulian Andrei Hotinceanu Andra Dan Livia Mălina Burtavel Anca-Elena Eftenoiu Diana Bârcă Andreea Ionescu Cerasela Paraschiv Viorica-Elena Rădoi

Epilepsy is a heterogeneous neurological disorder with a strong genetic basis, yet recent evidence underscores the critical role of epigenetic mechanisms in its pathogenesis. This review synthesizes current knowledge on how chromatin remodeling, histone modifications, DNA methylation, and transcriptional regulation intersect with classical channelopathies and signaling pathways. We emphasize how epigenetic dysregulation contributes to neuronal excitability and network plasticity, particularly through interactions with mTOR, PI3K-AKT, and GABAergic signaling cascades. The convergence of genetic mutations and epigenetic modifications creates a dynamic landscape in which environmental factors can modify gene expression and contribute to the development of epilepsy. Emerging therapeutic strategies—including epigenetic drugs (HDAC inhibitors, DNMT inhibitors), CRISPR/dCas9-based epigenome editing, and multi-omics approaches—offer promising avenues for precision medicine. This review provides a comprehensive synthesis of genetic and epigenetic mechanisms in epilepsy, examining how these layers interact to produce disease phenotypes and discussing the therapeutic implications of this multilayered regulation.

Epigenomes doi: 10.3390/epigenomes10010009

Authors: Riccardo Proietti Nicola Tidbury Joshua Preston Maanya Vittal Philippa McCabe Garry McDowell Gregory Y. H. Lip Manlio Vinciguerra

Background/Objectives: Atrial fibrillation (AF) is currently the most common arrhythmia worldwide, and it is linked to increased mortality and morbidity, hence the need for a better clinical stratification of AF patients. Histone complexes or nucleosomes, released into the blood circulation, are found elevated in acute conditions such as stroke, trauma, and sepsis. The aim of this pilot single-centre study was to assess whether circulating histone levels could be used for diagnostic purposes in patients with AF. Methods: A total of 40 patients, well characterised for their biochemical and clinical characteristics, were recruited from outpatient clinics. Patients were randomly recruited into two groups (n = 20 per group), i.e., persistent AF and hypertensive controls. A multi-channel flow imaging methodology based on ImageStreamX was used with a well-optimised protocol to image and quantify five individual histones (H2A, H2B, H3, H4, and macroH2A1.1) together with the dimers (H2A/H2B, and H3/H4). Results: In the AF groups, plasma levels of histone dimers H2A/H2B and H3/H4 were elevated compared to hypertensive controls, 1.8% vs. 1.06% (p-value = 0.03). H2A/H2B dimer levels were increased in AF patients irrespective of gender, smoking status, diabetes, and pharmacological therapy. In the overall population, an inverse correlation between H2A and BMI was detected. Conclusions: Our pilot study, although limited in sample size, suggests that circulating histone complexes may be epigenetic sentinels for AF, offering mechanistic insights while addressing unmet needs in risk stratification.

Epigenomes doi: 10.3390/epigenomes10010008

Authors: Jaclyn M. Goodrich Yaodong Xin Shawn C. Beitel John Gulotta Lu Wang Bhavya Thotakura Judith M. Graber Derek Urwin Alexander C. Mayer Sara Jahnke Derrick L. Edwards Casey Grant Sreenivasan Ranganathan Jefferey L. Burgess

Background/Objectives: High-risk, low-frequency incidents such as building collapses and large chemical fires can result in acute, high-dose exposures to toxic agents for first responders and the surrounding community. While these exposures may last for hours to days, their contribution to firefighters’ risks for cancer and other diseases is relatively unknown. In February 2023, a freight train transporting chemicals derailed and caught fire in East Palestine, Ohio, US. More than 350 firefighters, primarily volunteer, responded to the incident. In this cross-sectional study, we evaluated epigenetic markers of toxicity in responding firefighters. We hypothesized that exposures from responding to the train derailment would alter the expression of microRNAs (miRNAs) linked to carcinogenesis. Methods: We enrolled 62 responding firefighters and a comparison group of 26 firefighters from the same region who did not respond to the incident. We measured the relative expression of 800 miRNAs in blood samples using the nCounter Human v3 miRNA expression panel. We compared the expression of miRNA between exposure groups in negative binomial regression models, adjusting for potential confounders. Results: At a false discover rate cut-off of 5% (q-value < 0.05), 16 miRNAs had significantly higher expression and one significantly lower among firefighters that responded to the incident. Top disease-related pathways in which these miRNAs were enriched included those relevant to neurodegenerative diseases, vascular disease, and multiple cancer sites. Conclusions: Overall, results suggest responding to one large incident can have non-transient impacts on miRNA expression. Whether this translates into longer-term health risks or adaptive responses to exposures is unclear.

Epigenomes doi: 10.3390/epigenomes10010007

Authors: Victor T. Sy Sterling S. Trawick Hagen M. Tatarsky Patrick K. T. Shiu

In the filamentous fungus Neurospora crassa, a gene not having a pairing partner during meiosis is seen as a potential intruder and is targeted by a mechanism called meiotic silencing by unpaired DNA (MSUD). MSUD employs core RNA interference (RNAi) components such as the SMS-2 Argonaute, which uses small interfering RNAs (siRNAs) as guides to seek out mRNAs from unpaired genes for silencing. In Drosophila melanogaster, the heat shock protein 70 (Hsp70) chaperone system facilitates the conformational activation of an Argonaute and allows it to load siRNAs. Here, our results demonstrate that an Hsp70 protein in Neurospora interacts with SMS-2 and mediates the silencing of unpaired genes.

Epigenomes doi: 10.3390/epigenomes10010006

Authors: Michael M. Vierling Victor T. Sy Logan M. Decker Hua Xiao Justine N. Hemaya Patrick K. T. Shiu

The presence of an extra DNA segment in a genome could indicate a transposon or another repetitive element on the move. In Neurospora crassa, a surveillance mechanism called meiotic silencing by unpaired DNA (MSUD) is maintained to monitor these selfish elements. MSUD utilizes common RNA interference (RNAi) factors, including the SMS-2 Argonaute, to target mRNAs from genes lacking a pairing partner during meiosis. In eukaryotes, an mRNA transcript is typically bound at the 5′ cap by the cap-binding complex (CBC), which assists in its nuclear export. Previously, we discovered that CBC and its interactor NCBP3 mediate MSUD, possibly by guiding the perinuclear SMS-2 to effectively recognize exported mRNAs. Here, we report that ARS2, a CBC cofactor, is involved in MSUD. ARS2 interacts with both CBC and NCBP3, and it may help bring them together. In addition to its role in silencing, ARS2 also contributes to vegetative growth and sexual sporulation.

Epigenomes doi: 10.3390/epigenomes10010005

Authors: Nadezhda Milova Maria Nikolova Angel Yordanov Antoan Milov Stoilka Mandadzhieva

The connection between the mother and the child has been considered one of the strongest bonds in nature. Though there are numerous factors that can influence the establishment of pregnancy, in its essence, three are considered major: a good quality embryo, a receptive endometrium, and successful cross-talk between them. The placenta, which derives from the trophoblast of the embryo, develops when a successful implantation occurs. It is an ephemeral organ through which the turnover of nutrients, gases, and waste molecules is realized. It serves as a barrier and can provide the embryo with immune factors. Placental disorders are observed in some rare but life-threatening obstetric conditions like preeclampsia (PE), fetal growth restriction (FGR), gestational trophoblastic diseases (GTDs), and gestational diabetes mellitus (GDM). The etiology and pathogenesis of some are still partially enigmatic. Our attention in this review was driven by the participation of small RNA molecules—miRNAs and piRNAs—as potential epigenetic modulators of genes that play a pivotal role in placental functioning. In this study, we analyze the influence of these epigenetic factors on the mechanisms of the development of preeclampsia. The molecular approach for understanding placental disorders may help new diagnostic and therapeutic solutions to be found.

Epigenomes doi: 10.3390/epigenomes10010004

Authors: Nisha Ganesh William M. Grady Andrew M. Kaz

Colitis-associated colorectal cancer (CAC) represents a distinct subtype of colorectal malignancy that arises in the setting of chronic inflammatory bowel disease (IBD). Unlike sporadic colorectal cancer, CAC develops through inflammation-driven molecular pathways, in which epigenetic alterations play a pivotal role in tumor initiation and progression. This review highlights the major epigenetic mechanisms implicated in CAC, including DNA methylation, histone modifications, and microRNA (miRNA) dysregulation. Aberrant DNA methylation patterns, such as promoter hypermethylation of tumor suppressor genes and global hypomethylation, contribute to genomic instability and altered gene expression. In parallel, inflammation-induced changes in histone configuration modulate chromatin accessibility and transcriptional activity of key oncogenic and tumor-suppressive pathways. Furthermore, deregulated miRNAs influence multiple aspects of CAC pathogenesis by targeting genes involved in inflammation and tumor progression. Understanding these epigenetic processes provides valuable insights into the development of colorectal malignancy and identifies potential biomarkers for early detection and intervention in colitis-associated colorectal cancer.

Epigenomes doi: 10.3390/epigenomes10010003

Authors: Nazia Afroze Reham I. Alagal Lujain A. Almousa Ritu Raina Prathap Bava Lizna Mohamed Ali Tarique Noorul Hasan Arif Hussain

Purpose: The reversible deviant in epigenomic modulations is the highlight of developing new anti-cancer drugs, necessitating the use of fisetin as an epigenetic modifier in the study. Methods: In silico and molecular studies were performed to analyze the modulatory effect of fisetin on various writers and erasers. Further, whole genome DNA methylation sequencing and expression studies were performed. Global DNA methylation-LINE 1 kit was used to check global DNA methylation. Additionally, the effect of fisetin on migration was evaluated by colony, scratch, and invasion assays and qPCR and protein expression studies of migration-related genes were carried out on HeLa cells. Results: In silico studies have supported that fisetin interacts with writers and erasers in their catalytic site and the simulation studies showed minimum fluctuations in energy and temperature over a 10 ns timescale indicating that these complexes are likely to remain stable. Fisetin (20–50 µM) dose-dependently inhibited DNA methyltransferases (DNMT), histone deacetyl transferases (HDAC), histone acetyl transferases (HAT), and histone methyltransferases (HMT) activities at 48 h, with inhibition ranging from 24 to 72% compared to the control. The expression and enzymatic activity of these proteins, along with various H4 and H3 modification marks, were observed to be altered following fisetin treatment at 48 h. Fisetin treatment reduced promoter methylation in various tumor suppressor genes ranging from 15.29% to 76.23% and leading to the corresponding reactivation of important tumor suppressor genes; however, it did not lead to any alteration in the global DNA methylation compared to untreated controls linked with the anti-migratory properties of fisetin as the percentage of migrated cells dropped from ~40% to ~8%. Conclusions: This study gives a mechanistic insight of fisetin as a potential epigenetic modifier in HeLa cells.

Epigenomes doi: 10.3390/epigenomes10010002

Authors: Ivana Kašubová Andrea Hornáková Lucia Kotúľová Tomáš Rokos Zuzana Kolková Andrea Kapinová Terézia Pribulová Erik Kozubík Michal Kalman Kamil Biringer Erik Kúdela Veronika Holubeková

Background/Objectives: Cervical cancer is a common malignancy in women worldwide, closely associated with persistent human papillomavirus (HPV) infection. Epigenetic mechanisms, particularly promoter methylation, may contribute to tumour progression. This pilot study aimed to analyse the promoter methylation patterns and gene expression of selected genes (DNMT, BCL2, CDH1, CD8A, MUC1, ALCAM). The goal was to identify associations between promoter hypermethylation, gene expression, and HPV infection in cervical swab specimens obtained from patients with low-grade squamous intraepithelial lesions (SILs), high-grade SILs, or squamous cell carcinomas. Methods: A total of 81 cervical swab samples from Slovak participants were included in the study. DNA methylation and gene expression profiling was performed using real-time PCR (qPCR) and pyrosequencing. Results: BCL2 expression was significantly reduced across all lesion grades. CD8A expression was slightly elevated in low- and high-grade SILs, particularly in HPV-positive samples. MUC1 showed variability with lesion grade. No statistically significant differences in DNA methylation were observed across groups stratified by HPV status, community state type, and lesion grade. Conclusions: Our findings suggest that BCL2 downregulation and gene activity variability influenced by the vaginal microbiome may play a role in cervical lesion progression. These results highlight potential non-invasive biomarkers for monitoring cervical lesions.

Epigenomes doi: 10.3390/epigenomes10010001

Authors: Andrea Hornakova Zuzana Kolkova Lucia Kotulova Tomas Rokos Ivana Kasubova Terezia Pribulova Erik Kozubik Kamil Biringer Erik Kudela Veronika Holubekova

Background: Cervical cancer remains the fourth most common malignancy among women worldwide. Despite vaccination and regular screening, new molecular biomarkers are needed for improved early detection and risk assessment. MicroRNAs (miRNAs) play crucial roles in post-transcriptional regulation, and their dysregulation may contribute to cervical carcinogenesis. This study evaluated the expression of selected miRNAs in cervical swab samples and corresponding biopsies from women with various grades of cervical lesions and assessed their relationship with human papillomavirus (HPV) infection. Methods: A total of 72 cervical swab samples were included in this study, divided according to cytological severity: negative for intraepithelial lesion or malignancy (NILM, n = 15), atypical squamous cells of undetermined significance (ASC-US, n = 12), low-grade squamous intraepithelial lesion (LSIL, n = 19), and high-grade squamous intraepithelial lesion (HSIL, n = 26). In a subset of patients, corresponding biopsy specimens were analysed for comparison. The association of miRNA expression with HPV infection status was also examined. miRNA expression was quantified by real-time PCR using commercially available assays. Results: To assess the relationship between miRNA expression, lesion severity, and HPV infection, fold change values were compared to the control group (NILM). No significant differences were observed in the ASC-US group (p > 0.05). In contrast, several miRNAs were significantly upregulated in the LSIL and/or HSIL groups, as well as in HPV-positive samples, indicating their association with both lesion progression and viral infection. Specifically, miR-17-5p, miR-26b-5p, miR-29a-3p, miR-103a-3p, miR-106a-5p, miR-146a-5p, miR-155-5p, and miR-191-5p showed increased expression (p < 0.05) compared with controls. The observed upregulation of miR-26b-5p, miR-106a-5p, and miR-146a-5p highlights their potential role in HPV-associated cervical carcinogenesis. Dysregulated miRNAs were enriched in pathways related to infectious diseases, various types of cancer, and cell adhesion processes. Conclusions: The gradual increase in specific miRNAs with lesion severity and HPV infection suggests their role in cervical carcinogenesis. The identified miRNAs may serve as promising non-invasive biomarkers for early detection and monitoring of HPV-associated cervical lesions.

Epigenomes doi: 10.3390/epigenomes9040053

Authors: Valeria A. Korolenya Maxim L. Filipenko Mariya A. Smetanina

The endothelium, as the inner layer of the vascular wall, is in constant contact with blood components, so that leukocytes have the ability to adhere to endotheliocytes and penetrate to the subendothelial space. When studying heterogenic vascular samples containing endothelial cells or pathological processes related to inflammation within the endothelium, it may be necessary to distinguish DNA by endothelial and leukocyte origin, which is possible due to its specific epigenetic modifications. To identify CpG loci that could serve as markers for endothelial cells, we searched for their distinctive stable methylated or demethylated states by applying marginal filtering (selecting CpG loci with methylation Beta values closer to 0 and 1) to the microarray data and identified 47 CpG loci with relatively stable methylation/demethylation status that differentiate endothelial (HUVEC, HCMEC, HPAEC, HPMEC, and LSEC) DNA from leukocyte (granulocytes, monocytes, and lymphocytes) DNA. In addition, we compared CpG loci with high and low levels of DNA methylation between different types of endothelial cells and leukocytes. We believe that the obtained data will hopefully facilitate further studies on endothelial dysfunction.

Epigenomes doi: 10.3390/epigenomes9040052

Authors: Beatriz Andrea Otálora-Otálora César Payán-Gómez Juan Javier López-Rivera Luisa Fernanda Patiño-Unibio Sally Lorena Arboleda-Mojica Claudia Aristizábal-Guzmán Mario Arturo Isaza-Ruget Carlos Arturo Álvarez-Moreno

Background/Objectives: The oral–gut–lung axis represents a dynamic system where exosomes carrying mRNAs and non-coding RNAs might help to regulate microbiota and human cell crosstalk to establish transcriptional regulatory networks controlling cellular biological processes and signaling pathways. Methods: We conducted a comprehensive transcriptomic analysis to characterize the molecular cargo of extracellular exosomes in the context of gut and lung cancer. Results: By analyzing gut and lung exosomes cargo with our previous transcriptomic studies from tumoral and inflammatory tissues, we found that exosomes can transport key RNAs that codify specific receptors that facilitate pathogenic interaction with microorganisms and RNAs that are part of interacting gene and transcriptional regulatory networks that control the function of differentially expresses genes, all involved in biological processes like cell cycle, plasticity and growth regulation, invasion, metastasis, microenvironmental remodeling, epigenetic, and microbial and immunological modulation, during the unlocking of phenotypic plasticity for the acquisition of the hallmarks of cancer in the oral–gut–lung axis. Conclusions: Exosomal RNA regulation of transcriptional networks represents a pivotal axis in the interplay between inflammation and cancer, offering opportunities for innovative diagnostic and therapeutic approaches.

Epigenomes doi: 10.3390/epigenomes9040051

Authors: Stefano Amatori

Human life expectancy has risen dramatically in the last century, but this demographic triumph has come at the cost of an explosion of non-communicable diseases (NCDs), threatening the sustainability of healthcare systems in aging, low-fertility societies. Evolutionary medicine provides a framework to understand, at least in part, this paradox. Many vulnerabilities to disease are not failures of design but the predictable outcomes of evolutionary trade-offs, constraints, and mismatches. Evolutionary mismatch theory explains how traits once advantageous in ancestral environments become maladaptive in modern contexts of abundance, sedentarism, and urbanization. The developmental origins of health and disease (DOHaD) concept describes how epigenetic plasticity in early life can buffer or amplify these mismatches, depending on whether adult environments align with developmental forecasts. Transgenerational epigenetic inheritance, even if still debated in humans, may further influence phenotypic plasticity, increasing or mitigating the mismatch. In evolutionary terms, the theories of mutation accumulation, antagonistic pleiotropy, and the disposable soma explain why longer lifespans, and ecological and social conditions profoundly different from those in which we developed, increase the likelihood that these costs are expressed clinically. Because most NCDs can be prevented and effectively controlled but not cured, efforts should prioritize quality of life for people, families, and communities. At the individual level, aligning lifestyles with evolved biology can mitigate risk, but the greatest leverage lies in population-level interventions. Urban health strategies represent a forward-looking attempt to realign modern environments with human biology. In this way, the concept of the evolutionary misfit becomes not just a diagnosis of maladaptation, but a guide for building healthier, more sustainable societies.

Epigenomes doi: 10.3390/epigenomes9040050

Authors: Abhishu Chand Kyoungtae Kim

Quantum dots (QDs) have emerged as powerful tools in biomedical applications due to their unique optical and fluorescent properties which enable highly sensitive and multiplexed detection of biomolecules. Particularly in the field of epigenetic research, QDs are utilized as biosensors for monitoring changes in DNA methylation, microRNA (miRNA) expression, and histone modifications, providing a viable alternative to conventional assays. However, increasing evidence also suggests that QDs act as an epigenetic disruptor, altering epigenetic mechanisms and downstream cellular processes. This dual role raises important questions about the safety, reliability, and translational potential of QDs in clinical usage. Therefore, in this commentary we critically evaluate the advances of QD-based epigenetic sensing platforms while also providing insights into QD-based epigenetic dysregulation. We further discuss the current limitations and provide future directions to gain a better understanding of how QDs function to bridge the gap between their diagnostic potential and clinical integration.

Epigenomes doi: 10.3390/epigenomes9040049

Authors: Edward A. Ruiz-Narváez

Background/Objectives: Current genomics research equates the genome with DNA sequence and treats the epigenome as a regulatory layer. This DNA-centric view obscures the fact that genomic identity arises through epigenomic processes. The objective of this article is to reinterpret published findings into a new theoretical framework: the EpG2 (Epigenome–Genome) system. Methods: This work develops a new conceptual framework by integrating published evidence from diverse domains—including enhancer biology, overlapping genomic functions, alternative coding frames, zygotic genome activation, and disease-associated loci—and reinterpreting these findings through the lens of epigenomic processes. Results: Evidence shows that enhancers emerge only through the interplay of sequence, transcription factors, and chromatin environment. At fertilization, paternal and maternal genomes remain separate, and a new genome emerges through coordinated epigenomic reprogramming or zygote genome emergence (ZGE). DNA sequence risk variants illustrate the concept of contextual risk alleles, whose effects shift across tissues and developmental stages as epigenomic contexts change. Conclusions: The EpG2 system reframes the genome as a processual, emergent entity generated and regulated by epigenomic processes, offering a paradigm for understanding genomic variation beyond DNA sequence.

Epigenomes doi: 10.3390/epigenomes9040048

Authors: Alexandra L. Nowak Marvin A. Schilt-Solberg Xiaoyu Liang Fabiola Magaña Dawn P. Misra Carmen Giurgescu

Background: Prenatal depression, affecting up to a quarter of all pregnancies in the United States, contributes to morbidity and mortality and is associated with increased risk of adverse birth and long-term mental health outcomes. Adverse childhood experiences (ACEs, or experiences of abuse, neglect, or family dysfunction experienced prior to age 18) are a strong predictor of adult depression and adverse health outcomes. The present study investigated whether epigenetic modification in the form of DNA methylation (DNAm) of four stress-related, glucocorticoid pathway genes (CRH, CRHR1, FKBP5, NR3C1) mediates associations between ACEs and depressive symptoms among Black pregnant women. Methods: Using a cross-sectional design, we examined the mediating role of DNAm on the relationship between depressive symptoms (Center for Epidemiologic Studies Depression Scale (CES-D)) and ACEs (Centers for Disease Control and Prevention 10-item questionnaire), in a subsample (n = 61) of Black pregnant women who were participants of the Biosocial Impacts of Black Births (BIBB) study. Results: A significant association was found between ACEs and depressive symptoms scores (TE α_X = 2.29 with p_TE = 6.60 × 105). DNAm on five CpG sites within two genes significantly mediated the relationship between ACEs and depressive symptoms (cg03238273 on CRHR1, and cg08845721, cg16594263, cg19820298, and cg23430507 on NR3C1). Conclusions: This study provides evidence that DNAm partially mediated the association of ACEs and depressive symptoms during pregnancy among Black pregnant women. Understanding the molecular pathways underlying the mediating effect of ACEs on depressive symptoms among Black pregnant women can illuminate biological markers that help identify and treat pregnant women who are at an increased risk for depression following childhood trauma.

Epigenomes doi: 10.3390/epigenomes9040047

Authors: Antoan Milov Maria Nikolova Stoilka Mandadzhieva Nina Doncheva Nadezhda Milova Angel Yordanov

Circular RNAs (circRNAs) are small, non-coding RNAs in which the 5′ and 3′ ends are linked covalently by back-splicing of exons from a single pre-mRNA. More and more scientific evidence is gathered for their wide distribution in the animal world, playing the role of regulators for biological processes, being cell- and tissue-specific. They can influence cellular physiology by various molecular mechanisms, finally modulating gene expression. CircRNAs are believed nowadays to be expressed in both receptive and cancerous endometrium. Due to their abundant expression in the endometrial tissue and their small size and stability, they have been considered potential diagnostic markers and treatment targets for endometrial-related diseases. The regulation of proliferation and differentiation is essential for the formation of receptive endometrium and for endometrial cancer emergence and progression. The receptive endometrium can be regarded as the most highly differentiated state of the endometrium. In contrast, the cancerous endometrium is characterized by a high level of proliferation and the lowest degree of differentiation. These endometria could be conditionally considered opposites. We are investigating the circRNA–miRNA–mRNA regulatory networks that can promote or suppress the proliferation and differentiation of endometrial cells by activating specific signaling pathways in both receptive and cancerous endometria. It could be worth knowing whether there are universal endometrial switches responsible for proliferation and differentiation processes that can alter the balance between them. We are interested in their clinical application as biomarkers and therapeutic targets for both endometrial receptivity issues and EC cases, particularly in diagnosis, progression assessment, and outcome prediction.

Epigenomes doi: 10.3390/epigenomes9040046

Authors: Emanuela Talarico Eleonora Greco Francesco Guarasci Fabrizio Araniti Adriana Chiappetta Leonardo Bruno

Rice (Oryza sativa L.) is a staple food for over half the global population and a model organism for monocot plant research. However, it is susceptible to salinity, with most cultivated varieties showing reduced growth at salt levels above 3 dS/m. Despite numerous efforts to improve its salt tolerance, little progress has been made. A promising area of research lies in the study of epigenetic regulation, which encompasses DNA methylation, histone modifications, and chromatin remodelling. These processes play a crucial role in mediating how plants respond to salt stress by modulating gene expression. This often results in heritable changes that can be used as molecular markers. Studies in rice and other cereals have demonstrated a clear association between histone alterations, shifts in DNA methylation patterns, and the expression of salt-responsive genes. Furthermore, epigenetic mechanisms contribute to the development of stress memory, enabling plants to respond more effectively to recurring stressful conditions. Understanding these regulatory pathways offers new opportunities for breeding or engineering salt-tolerant rice varieties, potentially leading to improved crop resilience and productivity under saline conditions.

Epigenomes doi: 10.3390/epigenomes9040045

Authors: Sebastian Gaston Alvarado Annaliese Chang Maral Tajerian

Background: Trait convergence or parallelism is widely seen across the animal and plant kingdoms. For example, the evolution of eyes in cephalopods and vertebrate lineages, wings in bats and insects, or shark and dolphin body shapes are examples of convergent evolution. Such traits develop as a function of environmental pressures or opportunities that lead to similar outcomes despite the independent origins of underlying tissues, cells, and gene transcriptional patterns. Our current understanding of the molecular processes underlying these phenomena is gene-centric and focuses on how convergence involves the recruitment of novel genes, the recombination of gene products, and the duplication and divergence of genetic substrates. Scope: Despite the independent origins of a given trait, these model organisms still possess some form of epigenetic processes conserved in eukaryotes that mediate gene-by-environment interactions. These traits evolve under similar environmental pressures, so attention should be given to plastic molecular processes that shape gene function along these evolutionary paths. Key Mechanisms: Here, we propose that epigenetic processes such as histone-modifying machinery are essential in mediating the dialog between environment and gene function, leading to trait convergence across disparate lineages. We propose that epigenetic modifications not only mediate gene-by-environment interactions but also bias the distribution of de novo mutations and recombination, thereby channeling evolutionary trajectories toward convergence. An inclusive view of the epigenetic landscape may provide a parsimonious understanding of trait evolution.

Epigenomes doi: 10.3390/epigenomes9040044

Authors: Milad Shirvaliloo Sepideh Khoee Samideh Khoei Roghayeh Sheervalilou Parisa Mohammad Hosseini Reza Afzalipour Sakine Shirvalilou

Background/Objectives: Histone acetylation regulates gene expression and plays a key role in cancer pathophysiology. Nanotherapeutics are known to modulate histone acetylation and influence cancer progression. This systematic scoping review examines the effects of nanotherapeutics on histone acetylation enrichment across multiple cancers. Methods: A systematic search of Embase, PubMed/MEDLINE, Scopus, and Web of Science was conducted in accordance with the PRISMA 2020 statement. A total of 13 studies were included. Data were analyzed and visualized in R, and risk of bias was assessed with ToxRTool (OSF Registration: 10.17605/OSF.IO/E643S). Results: Nanotherapeutics were most commonly evaluated against breast (21.4%), prostate (21.4%), pancreatic (14.3%), and bladder (14.3%) cancers. Primary nanomaterials used in the synthesis of nanotherapeutics included poly(lactic-co-glycolic acid) (25.0%), gold (21.4%) and arsenic oxide (21.4%) nanoparticles. Studied histone acetylation marks included H3K9ac, H3K14ac, H3K27ac and H4K16ac. Treatment with nanotherapeutics increased histone H3 and H4 acetylation enrichment, particularly H3K14ac in colorectal and prostate cancers and H4K16ac in ovarian cancer. Conversely, gold-based nanotherapeutics decreased H3K9ac and H3K14ac enrichment in breast cancer. The optimal concentration for most nanotherapeutics was ≤25 µM, with PpIX-FFYSV showing the strongest anticancer effect (viability <25%). Across four preclinical studies (n = 58), treatment with the nanotherapeutics reduced tumor size to less than 50% of control in 64% of animals (95% CI: 21–92%, I2 = 63.8%). Altered histone acetylation was associated with differential expression of CDKN1A, HSPA1, SREBF2 and TGFB. Conclusions: The evidence demonstrates that nanotherapeutics can alter histone acetylation patterns by modulating EP300/CBP, GCN5 and HDAC, preventing cancer progression and invasion.

Epigenomes doi: 10.3390/epigenomes9040043

Authors: Eleonora Greco Emanuela Talarico Francesco Guarasci Marina Camoli Anna Maria Palermo Alice Zambelli Adriana Chiappetta Fabrizio Araniti Leonardo Bruno

Heavy metal and metalloid stress, particularly from toxic elements like cadmium (Cd), poses a growing threat to plant ecosystems, crop productivity, and global food security. Elevated concentrations of these contaminants can trigger cytotoxic and genotoxic effects in plants, severely impairing growth, development, and reproduction. In recent years, epigenetic mechanisms have emerged as crucial regulators of plant responses to heavy metal stress, offering novel insights and strategies for enhancing plant resilience in contaminated environments. This review synthesises current advances in the field of plant epigenetics, focusing on key modifications such as DNA methylation, histone acetylation and remodelling, chromatin dynamics, and small RNA-mediated regulation. These processes not only influence gene expression under metal-induced stress but also hold promise for long-term adaptation through transgenerational epigenetic memory. Recent developments in high-throughput sequencing and functional genomics have accelerated the identification of epigenetic markers associated with stress tolerance, enabling the integration of these markers into breeding programs and targeted epigenome editing strategies. Special attention is given to cadmium stress responses, where specific epigenetic traits have been linked to enhanced tolerance. As plant epigenomic research progresses, its application in sustainable agriculture becomes increasingly evident offering environmentally friendly solutions to mitigate the impact of heavy metal pollution. This review provides a foundation for future research aimed at leveraging epigenetic tools to engineer crops capable of thriving under metal stress, thereby contributing to resilient agricultural systems and sustainable food production.

Epigenomes doi: 10.3390/epigenomes9040042

Authors: Rakesh Srivastava Niraj Lodhi

N6-methyladenosine (m6A) is the most abundant and dynamic RNA modification in eukaryotic messenger and non-coding RNAs, playing a pivotal role in the post-transcriptional regulation of gene expression. The coordinated actions of m6A writers, erasers, and readers influence transcript stability, immune activation, and pathogen suppression. Growing evidence indicates that m6A fine-tunes the expression of defense-related genes, modulates RNA processing events, and is frequently hijacked by pathogens and pests to promote virulence. Notably, the dual role of m6A in enhancing plant defense and facilitating pathogen adaptation highlights its significance in the host–pathogen arms race. This review emphasizes recent advances in our understanding of m6A-mediated epitranscriptomic regulation in plants, with a focus on its role in responses to biotic stresses, including fungi, bacteria, virus infections, insects, and nematode attacks. This regulatory layer offers novel opportunities for crop protection through targeted manipulation of the epitranscriptomic mechanism.

Epigenomes doi: 10.3390/epigenomes9040041

Authors: Mullen Boulter Ryan Collins Kyle K. Biggar

Lysine methylation is a critical post-translational modification catalyzed by lysine methyltransferases (KMTs), originally characterized in the regulation of histones. However, the breadth of non-histone targets remains largely unexplored. Here, we used a systematic peptide array-based approach to define a substrate preference motif for the SET-domain-containing KMT MLL4 (KMT2D), a member of the COMPASS complex and a known H3K4 methyltransferase. Using this motif, we identified CXXC finger protein 1 (CFP1), a core component of Setd1A/B complexes, as a putative MLL4 substrate. In vitro methyltransferase assays confirmed robust methylation of CFP1 by an MLL4-WRAD complex. Surprisingly, while initial predictions implicated K328, array-based methylation profiling revealed multiple lysine residues within CFP1’s lysine-rich basic domain as methylation targets, including K331, K335, K339, and K340. We further demonstrated that CFP1 methylation likely modulates its interaction with MLL4’s PHD cassettes and facilitates binding to Setd1A. Binding preferences of MLL4’s PHD1–3 and PHD4–6 domains varied with methylation state and site, suggesting non-histone methyl mark recognition by these cassettes. Pulldown assays confirmed that methylated, but not unmethylated, CFP1 binds Setd1A, supporting a potential methyl-switch mechanism. Together, our findings propose CFP1 as a potential non-histone substrate of MLL4 and suggest that MLL4 may regulate Setd1A/B function indirectly via CFP1 methylation. This study expands the substrate landscape of MLL4 and lays the groundwork for future investigations into non-histone methylation signaling in chromatin regulation.

Epigenomes doi: 10.3390/epigenomes9040040

Authors: Steven R. H. Beach Robert A. Philibert Mei-Ling Ong Man-Kit Lei Kaixiong Ye

Background: Heart disease may take a greater toll on Black Americans than White Americans despite similar levels of traditional risk factors. Elevated alcohol consumption (EAC) and chronic inflammation are two potentially important additional risk factors to consider. Both are relevant to understanding health disparities in cardiovascular health. Methods: Couples with a Black preadolescent or early adolescent child living in the home were recruited and followed. In waves 5 and 6 of data collection, biological samples were also collected allowing the characterization of elevated alcohol consumption, chronic inflammation, and cardiac risk using DNA methylation indices. 383 individual partners comprising 221 couples were examined across the two waves of data, yielding 661 person-wave observations from 383 individuals. Results: EAC at wave 5 forecast increased cardiac risk at W6 (R2 change = 0.276), β = −0.193, p = 0.001. However, chronic inflammation at wave 5 did not add significantly to the baseline model, β = −0.042, p = 0.549. Conversely, the slope of change for chronic inflammation was associated with slope of change in cardiac risk (R2 change = 0.111), b = −0.014, p = <0.001, but EAC change was not significantly associated with change in cardiac risk, b = −0.001, p = 0.185. Conclusions: Elevated alcohol consumption may be an important risk factor for increased cardiac risk over time in middle age. If so, it could be an important avenue for preventative intervention to decrease cardiac risk. Future research should examine whether similar associations are observed for other racial or minoritized groups and for non-minoritized groups.

Epigenomes doi: 10.3390/epigenomes9040039

Authors: Mackenzie Rubens Paul Ruiz Pinto Anita Sathyanarayanan Olivia Miller Amy B. Mullens Dagmar Bruenig Patricia Obst Jane Shakespeare-Finch Divya Mehta

Background: Posttraumatic growth (PTG) refers to positive psychological change following trauma. While its psychological aspects are well-documented, the biological mechanisms remain unclear. Epigenetic changes, such as DNA methylation (DNAm), may offer insight into PTG’s neurobiological basis. Aims: This study aimed to identify epigenetic markers associated with PTG using an epigenome-wide association study (EWAS), the first of its kind in a trauma-exposed population. Methods: A longitudinal EWAS design was used to assess DNAm before and after trauma exposure in first-year paramedicine students (n = 39). Genome-wide methylation data were analyzed for associations with PTG, applying epigenome-wide and gene-wise statistical thresholds. Pathway enrichment analysis was also conducted. Results: The study identified two CpGs (cg09559117 and cg05351447) within the PCDHA1/PCDHA2 and PDZD genes significantly associated with PTG at the epigenome-wide threshold (p < 9.42 × 10–8); these were replicated in an independent sample. DNAm in 5 CpGs across known PTSD candidate genes ANK3, DICER1, SKA2, IL12B and TPH1 were significantly associated with PTG after gene-wise Bonferroni correction. Pathway analysis revealed that PTG-associated genes were overrepresented in the Adenosine triphosphate Binding Cassette (ABC) transporters pathway (p = 2.72 × 10−4). Conclusions: These results identify genes for PTG, improving our understanding of the neurobiological underpinnings of PTG.

Epigenomes doi: 10.3390/epigenomes9040038

Authors: Shenghui Mi Hideyuki Nakashima Kinichi Nakashima

Aging of the central nervous system (CNS) involves widespread transcriptional and structural remodeling, prominently marked by synaptic loss, impaired neurogenesis, and glial dysfunction. While age-related gene expression changes have been documented for decades, recent genome-wide next-generation sequencing studies emphasize the importance of epigenetic mechanisms—such as DNA methylation and histone modification—in shaping these profiles. Notably, these modifications are potentially reversible, making them promising targets for therapeutic intervention. However, the mechanisms by which age-associated factors, such as inflammation and oxidative stress, orchestrate these epigenetic alterations across distinct CNS cell types remain poorly understood. In this review, we propose a framework for understanding how aging and neuroinflammation are regulated by epigenetic mechanisms, contributing to brain dysfunction and disease vulnerability.

Epigenomes doi: 10.3390/epigenomes9040037

Authors: Arathi Pillai Sibin M Kandi Nidhi Tripathy Deeptika Agarwal Indrani Mukhopadhyay Bhasker Mukherjee Y Vashum

Background: The role of circulatory miRNAs in gestational diabetes mellitus (GDM) was explored extensively in previous studies. However, there was limited literature on longitudinal studies exploring the changes in miRNA expression during pregnancy and postpartum to understand the changes in their expression levels in GDM patients. Methods: Blood samples from thirty GDM subjects and twenty normoglycemic pregnant women (NGT) were collected between 24 and 28 weeks of their pregnancy, and follow-up samples from the same subjects were collected till 12 weeks postpartum (FGDM and FNGT, respectively). Three candidate miRNAs, hsa-miR-16-5p, hsa-miR-17-5p, and hsa-miR-20a-5p, were quantified from their plasma samples using RT-qPCR. Comparative analysis of these miRNA expression levels was made between different groups. Results: hsa-miR-16-5p, hsa-miR-17-5p, and hsa-miR-20a-5p expression were significantly higher in GDM patients when compared to NGT subjects. Interestingly, hsa-miR-17-5p has shown consistent upregulation in FGDM even after these patients turned normoglycemic. Additionally, hsa-miR-16-5p was found to be higher in FGDM patients compared to FNGT subjects. Conclusions: The present study corroborated the finding of differential expression of hsa-miR-16-5p, hsa-miR-17-5p, and hsa-miR-20a-5p in GDM. It also marked the importance of monitoring the levels of hsa-miR-17-5p and hsa-miR-16-5p during pregnancy and postpartum in GDM patients.

Epigenomes doi: 10.3390/epigenomes9030036

Authors: Ambrose Loc Ngo Linda Nguyen Niki Gharavi Alkhansari Huiping Zhang

N6-methyladenosine (m6A) is the most prevalent internal modification in eukaryotic messenger RNA (mRNA) and plays a vital role in post-transcriptional gene regulation. In recent years, m6A has emerged as a pivotal epitranscriptomic signal involved in neural development, synaptic remodeling, and the molecular pathophysiology of neuropsychiatric disorders. In this review, we summarize the mechanisms underlying the deposition, removal, and recognition of m6A by dedicated methyltransferases, demethylases, and RNA-binding proteins. We further explore how these dynamic modifications influence neuronal differentiation and memory formation. Recent studies have linked aberrant m6A regulation to psychiatric conditions such as depression, anxiety, schizophrenia, and bipolar disorder. Additionally, we discuss how pharmacological or genetic modulation of m6A pathways may promote adaptive neural plasticity and enhance cognitive and emotional resilience. Despite these promising findings, significant challenges remain in achieving spatial and temporal specificity while minimizing off-target effects in the brain. Therefore, we advocate for more in-depth investigations into m6A function within developmentally defined neural circuits to better understand its enduring role in maintaining neural homeostasis.

Epigenomes doi: 10.3390/epigenomes9030035

Authors: Thibaut Renard Serge Aron

Background/Objectives: The DNA methylome allows environmental signals to be converted into stable and adaptive changes in gene expression. While 5-methylcytosine (5mC) has been extensively studied, alternative epigenetic marks such as N6-methyladenine (6mA) and 5-hydroxymethylcytosine (5hmC) remain poorly understood. Comparative studies of these marks are rare, and their results are often confounded by phylogeny, tissue type, developmental stage, or methodology. Here, we aimed to disentangle the constitutive, somatic- and germline-specific, and/or age-related patterns displayed by 6mA, 5mC, and 5hmC within a single species. Methods: We generated long-read nanopore sequencing data for somatic tissues of buff-tailed bumblebee (Bombus terrestris) males and their sperm, enabling simultaneous detection of 6mA, 5mC, and 5hmC. We used a stepwise approach to successively identify (i) constitutive patterns conserved between somatic tissues and sperm, (ii) differences between the soma and the germline, and (iii) age-related changes between young and old males. Results: We found distinct constitutive, somatic and sperm, and age-related specific signatures in the genomic contexts, maintenance fidelity, and biological functions associated with 6mA, 5mC, and 5hmC. Sperm cells consistently displayed lower methylation entropy than did somatic tissues, indicating more stable methylation patterns in the germline. 5mC exhibited the greatest variation across all genomic contexts; 6mA and 5hmC displayed less dramatic differences. The influence of age was subtler but revealed context-dependent remodeling of methylation, particularly for 5hmC. Conclusions: We observed that 6mA, 5mC, and 5hmC displayed constitutive, somatic- and sperm-specific, and age-related differences that were associated with distinct genomic contexts and biological functions, supporting the complementarity of these methylation marks and their diverging epigenetic roles.

Epigenomes doi: 10.3390/epigenomes9030034

Authors: Barbara Mitsuyasu Barbosa Alexandre Todorovic Fabro Roberto da Silva Gomes Claudia Aparecida Rainho

Background: Pancreatic ductal adenocarcinoma (PDAC) is a highly heterogeneous malignancy, characterized by low tumor cellularity, a dense stromal response, and intricate cellular and molecular interactions within the tumor microenvironment (TME). Although bulk omics technologies have enhanced our understanding of the molecular landscape of PDAC, the specific contributions of non-malignant immune and stromal components to tumor progression and therapeutic response remain poorly understood. Methods: We explored genome-wide DNA methylation and transcriptomic data from the Cancer Genome Atlas Pancreatic Adenocarcinoma cohort (TCGA-PAAD) to profile the immune composition of the TME and uncover gene co-expression networks. Bioinformatic analyses included DNA methylation profiling followed by hierarchical deconvolution, epigenetic age estimation, and a weighted gene co-expression network analysis (WGCNA). Results: The unsupervised clustering of methylation profiles identified two major tumor groups, with Group 2 (n = 98) exhibiting higher tumor purity and a greater frequency of KRAS mutations compared to Group 1 (n = 87) (p < 0.0001). The hierarchical deconvolution of DNA methylation data revealed three distinct TME subtypes, termed hypo-inflamed (immune-deserted), myeloid-enriched, and lymphoid-enriched (notably T-cell predominant). These immune clusters were further supported by co-expression modules identified via WGCNA, which were enriched in immune regulatory and signaling pathways. Conclusions: This integrative epigenomic–transcriptomic analysis offers a robust framework for stratifying PDAC patients based on the tumor immune microenvironment (TIME), providing valuable insights for biomarker discovery and the development of precision immunotherapies.

Epigenomes doi: 10.3390/epigenomes9030033

Authors: Yalong Wang

The innate immune system protects against infection and cellular damage by recognizing conserved pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). Emerging evidence suggests that aberrant epigenetic modifications—such as altered DNA methylation and histone marks—can serve as immunogenic signals that activate pattern recognition receptor (PRR)-mediated immune surveillance. This review explores the concept that epigenetic marks may function as DAMPs or even mimic PAMPs. I highlight how unmethylated CpG motifs, which are typically suppressed using host methylation, are recognized as foreign via Toll-like receptor 9 (TLR9). I also examine how cytosolic DNA sensors, including cGAS, detect mislocalized or hypomethylated self-DNA resulting from genomic instability. In addition, I discuss how extracellular histones and nucleosomes released during cell death or stress can act as DAMPs that engage TLRs and activate inflammasomes. In the context of cancer, I review how epigenetic dysregulation can induce a “viral mimicry” state, where reactivation of endogenous retroelements produces double-stranded RNA sensed by RIG-I and MDA5, triggering type I interferon responses. Finally, I address open questions and future directions, including how immune recognition of epigenetic alterations might be leveraged for cancer immunotherapy or regulated to prevent autoimmunity. By integrating recent findings, this review underscores the emerging concept of the epigenome as a target of innate immune recognition, bridging the fields of immunology, epigenetics, and cancer biology.

Epigenomes doi: 10.3390/epigenomes9030032

Authors: Agnieszka Lovett Graham A. Hitman Georgios K. Dimitriadis Alice M. Murphy Gyanendra Tripathi Aparna Duggirala

Background/Objectives: Metabolic/bariatric surgery is currently the most successful treatment for patients with obesity; however, a fifth of patients undergoing surgery may not lose enough weight to be considered successful. Recent studies have shown that bariatric/metabolic surgery alters the epigenome and may explain postoperative improvements in metabolic health. The primary objective is to consolidate published differentially methylated CpG sites in pre- and post-metabolic/bariatric surgery female patients and associate them with the respective genes and pathways. Methods: This systematic review adhered to the PRISMA-P guidelines and was registered with the PROSPERO (CRD42023421852). Following an initial screening of 541 studies using COVIDENCE, six studies were selected, comprising three epigenome-wide association studies (EWAS) and three candidate gene methylation studies. The published studies collected DNA samples from female patients with obesity before and after surgery (3 months, 6 months, 9–31 months, and 2 years). KEGG pathway analysis was performed on genes where the extracted CpG sites were located. Results: The meta-analysis showed that 11,456 CpG sites are differentially methylated after a successful weight loss surgery, with 109 sites mapped to genes involved in key metabolic pathways, including FoxO, mTOR, insulin, cAMP, adipocytokine, Toll-like receptor, and PI3K-Akt. Conclusion: The highlighted differentially methylated CpG sites can be further used to predict the molecular signature associated with successful metabolic/bariatric surgery.

Epigenomes doi: 10.3390/epigenomes9030031

Authors: Niraj Lodhi Rakesh Srivastava

Epigenetic regulation, particularly DNA methylation, plays a crucial role in plant adaptation to environmental stresses by modulating gene expression without altering the underlying DNA sequence. In response to major abiotic stresses such as salinity, drought, heat, cold, and heavy metal toxicity, plants undergo dynamic changes in DNA methylation patterns. These modifications are orchestrated by DNA methyltransferases and demethylases with variations depending on plant species, genetic background, and ontogenic phase. DNA methylation affects the expression of key genes involved in cellular, physiological, and metabolic processes essential for stress tolerance. Furthermore, it contributes to the establishment of stress memory, which can be transmitted across generations, thereby enhancing long-term plant resilience. The interaction of DNA methylation with other epigenetic mechanisms, including histone modifications, small RNAs, and chromatin remodeling, adds layers of regulatory complexity. Recent discoveries concerning N6-methyladenine have opened new avenues for understanding the epigenetic landscape in plant responses to abiotic stress. Overall, this review addresses the central role of DNA methylation in regulating plant stress responses and emphasizes its potential for application in crop improvement through epigenetic and advanced biotechnological approaches.

Epigenomes doi: 10.3390/epigenomes9030030

Authors: Christina Stylianides Gavriel Hadjigavriel Paschalis Theotokis Efstratios Vakirlis Soultana Meditskou Maria Eleni Manthou Iasonas Dermitzakis

Neurocutaneous syndromes, known as phakomatoses, encompass a diverse group of congenital conditions affecting the nervous system and skin, with neurofibromatosis type 1 (NF1) and neurofibromatosis type 2 (NF2) among the most clinically significant. Both disorders are inherited in an autosomal dominant manner. NF1 presents with café-au-lait macules; cutaneous, subcutaneous, and plexiform neurofibromas; skeletal abnormalities; learning disabilities; and optic pathway gliomas, while NF2 is characterised by bilateral vestibular schwannomas, multiple meningiomas, ependymomas, and peripheral nerve schwannomas. Although germline mutations in the NF1 and NF2 tumour suppressor genes are well established, they do not fully explain the broad clinical variability observed, even among individuals carrying identical mutations. As increasingly recognised in other genetic diseases, epigenetic mechanisms, including DNA methylation, histone modifications, chromatin remodelling, and non-coding RNA (ncRNA) regulation, play a critical role in modulating gene expression and influencing disease severity. Despite important findings, the research remains fragmented, and a unified model is lacking. This review organises the current knowledge, emphasising how epigenetic alterations impact disease behaviour and outlining their potential as prognostic biomarkers and therapeutic targets. A deeper understanding of these mechanisms could lead to improved personalised management and the development of targeted epigenetic therapies for individuals with NF1 and NF2.

Epigenomes doi: 10.3390/epigenomes9030029

Authors: Claudia E. Rübe Mutaz A. Abd Al-razaq Carola Meier Markus Hecht Christian Rübe

The impact of ionizing radiation (IR) with induction of various DNA damage is based not only on genetic but also on epigenetic effects. Epigenetic modifications determine the chromatin structure and DNA accessibility, thereby regulating cellular functions through the expression of individual genes or entire groups of genes. However, the influence of DNA repair processes on the restoration of local chromatin structures and global nuclear architectures is still insufficiently understood. In multicellular organisms, epigenetic mechanisms control diverse cellular functions of specific cell types through precise temporal and spatial regulation of gene expression and silencing. How altered epigenetic mechanisms regulate the pathophysiological function of cells, tissues, and ultimately entire organs following IR exposure remains to be investigated in detail. Radiation-induced epigenetic processes are particularly critical for immature cell populations such as tissue-specific stem and progenitor cells during development and differentiation of organ tissues. Genome-wide patterns of DNA and histone modifications are established cell types—specifically during the development and differentiation of organ tissues but can also be fundamentally altered in adult organism by stress responses, such as radiation-induced DNA damage. Following IR exposure, epigenetic factors are not always fully restored to their original state, resulting in epigenetic dysfunction that causes cells to lose their original identity and function. Moreover, severe radiation-induced DNA damage can induce premature senescence of cells in complex tissues, which ultimately leads to signs of aging and age-related diseases such as cancer. In this work, we provide an overview of the most important epigenetic changes following IR exposure and their pathophysiological significance for the development of acute and chronic radiation reactions.

Epigenomes doi: 10.3390/epigenomes9030028

Authors: Nadezhda P. Babushkina Elena Yu. Bragina Densema E. Gomboeva Iuliia A. Koroleva Sergey N. Illarioshkin Sergey A. Klyushnikov Nataliya Yu. Abramycheva Maria A. Nikitina Valentina M. Alifirova Nikolai V. Litviakov Marina K. Ibragimova Matvey M. Tsyganov Irina A. Tsydenova Aleksei A. Zarubin Irina A. Goncharova Maria V. Golubenko Ramil R. Salakhov Aleksei A. Sleptcov Aksana N. Kucher Maria S. Nazarenko Valery P. Puzyrev

Background. Studies of comorbid (syntropic) and inversely comorbid (rarely occurring together, i.e., dystropic) diseases have focused on the search for molecular causes of this phenomenon. Materials. We investigated DNA methylation levels in regulatory regions of 23 apoptosis-associated genes as candidate loci associated with the “cancer–neurodegeneration” dystropy in patients with Huntington’s disease (HD) and patients with non–small cell lung cancer (LC). Results. Statistically significant differences in methylation levels between the HD and LC groups were found for 41 CpG sites in 16 genes. The results show that five genes (SETDB1, TWIST1, HDAC1, SP1, and GRIA2) are probably involved in the phenomenon of inverse comorbidity of these diseases. For these genes, the methylation levels of the studied CpG sites were altered in opposite directions in the two groups of patients, compared to the control group. Conclusions. For the SP1 gene, the above hypothesis is supported by our analysis of open-access data on gene expression in patients with the aforementioned diagnoses and fits a probable mechanism of the “HD–LC” dystropy.

Epigenomes doi: 10.3390/epigenomes9030027

Authors: Arif Ul Hasan Sachiko Sato Mami Obara Yukiko Kondo Eiichi Taira

Background/Objectives: Glioblastoma (GBM) is an aggressive brain tumor known for its profound heterogeneity and treatment resistance. Dysregulated complement signaling and epigenetic alterations have been implicated in GBM progression. This study identifies kynureninase (KYNU), a key enzyme in the kynurenine pathway, as a novel regulator of complement components and investigates its interaction with histone deacetylase 6 (HDAC6) in the context of therapeutic targeting. Methods: KYNU expression, and its association with complement signaling in GBM, were analyzed using publicly available datasets (TCGA, GTEx, HPA). Pathway enrichment was performed via LinkedOmics. In vitro studies in GBM cell lines (U87, U251, T98G) assessed the effects of KYNU silencing and treatment with an HDAC6 inhibitor (tubastatin) and a BET inhibitor (apabetalone) on gene expression and cell viability. Results: Bioinformatic analyses revealed significant overexpression of KYNU in GBM tissues compared to normal brain tissue. KYNU expression was positively associated with genes involved in complement and coagulation cascades. In vitro experiments demonstrated that KYNU silencing reduced the expression of C3, C3AR1, and C5AR1 and suppressed GBM cell viability. Treatment with tubastatin, while reducing viability, paradoxically upregulated complement genes, suggesting potential limitations in therapeutic efficacy. However, this effect was mitigated by KYNU knockdown. Combined treatment with apabetalone and tubastatin effectively suppressed KYNU expression and enhanced cytotoxicity, particularly in cells with high complement expression. Conclusions: Our findings establish the KYNU–HDAC6–complement axis as a critical regulatory pathway in GBM. Targeting KYNU-mediated complement activation through combined epigenetic approaches—such as HDAC6 and BET inhibition—represents a promising strategy to overcome complement-driven resistance in GBM therapy.

Epigenomes doi: 10.3390/epigenomes9030026

Authors: Letitia Y. Graves Melissa R. Alcorn E. Ricky Chan Katelyn Schwartz M. Kristi Henzel Marinella Galea Anna M. Toth Christine M. Olney Kath M. Bogie

Background/Objectives: This study investigated variations in DNA methylation patterns associated with chronic pain and propensity for recurrent pressure injuries (PrI) in persons with spinal cord injury (SCI). Methods: Whole blood was collected from 81 individuals with SCI. DNA methylation was quantified using Illumina genome-wide arrays (EPIC and EPICv2). Comprehensive clinical profiles collected included secondary health complications, in particular current PrI and chronic pain. Relationships between recurrent PrI and chronic pain and whether the co-occurrence of both traits was mediated by changes in DNA methylation were investigated using R packages limma, DMRcate and mCSEA. Results: Three differentially methylated positions (DMPs) (cg09867095, cg26559694, cg24890286) and one region in the micro-imprinted locus for BLCAP/NNAT are associated with chronic pain in persons with SCI. The study cohort was stratified by PrI status to identify any sites associated with chronic pain and while the same three sites and region were replicated in the group with no recurrent PrI, two novel, hypermethylated (cg21756558, cg26217441) sites and one region in the protein-coding gene FDFT1 were identified in the group with recurrent PrI. Gene enrichment and genes associated with specific promoters using MetaScape identified several shared disorders and ontology terms between independent phenotypes of pain and recurrent PrI and interactive sub-groups. Conclusions: DMR analysis using mCSEA identified several shared genes, promoter-associated regions and CGI associated with overall pain and PrI history, as well as sub-groups based on recurrent PrI history. These findings suggest that a much larger gene regulatory network is associated with each phenotype. These findings require further validation.

Epigenomes doi: 10.3390/epigenomes9030025

Authors: Elena-Cristina Găitănaru Roua Gabriela Popescu Andreea-Angelica Stroe Sergiu Emil Georgescu George Cătălin Marinescu

Background/Objectives: Advances in nanopore sequencing have opened new avenues for studying DNA methylation at single-base resolution, yet their application in epigenetic ageing research remains underdeveloped. Methods: We present a novel framework that leverages the unique capabilities of nanopore sequencing to profile and interpret age-associated methylation patterns in native DNA. Results: Unlike conventional array-based approaches, long reads sequencing captures full CpG context, accommodates diverse and repetitive genomic regions, removes bisulfite conversion steps, and is compatible to the latest reference genome. Conclusions: This work establishes nanopore sequencing as a powerful tool for next-generation epigenetic ageing studies, offering a scalable and biologically rich platform for anti-ageing interventions monitoring and longitudinal ageing studies.

Epigenomes doi: 10.3390/epigenomes9030024

Authors: Su Chen John W. Holloway Wilfried Karmaus Hongmei Zhang S. Hasan Arshad Susan Ewart

Background/Objectives: The experience of pregnancy and parturition has been associated with long-term health effects in mothers, imparting protective effects against some diseases while the risk of other diseases is increased. The mechanisms that drive these altered disease risks are unknown. This study examined DNA methylation (DNAm) changes from pre-pregnancy to several years after giving birth in parous women compared to nulliparous controls over the same time interval. Methods: Using 180 parous-associated CpGs, three analyses were carried out to test DNAm changes from pre-pregnancy at age 18 years to gestation; from gestation to post-pregnancy at age 26 years in parous women; and from 18 to 26 years in nulliparous women using linear mixed models with repeated measures. Results: The directions of DNAm changes were the same between the parous and nulliparous groups. Most CpG dinucleotides (67%, 121 of 180) had a decreasing trend while a small number (7%, 13 of 180) had an increasing trend. Of the CpGs showing increasing or decreasing DNAm, approximately half had DNAm change to a smaller extent in parous women and the other half changed more in parous women than nulliparous controls. 9% (17 of 180) changed significantly in nulliparous women only, leading to a significant difference in DNAm levels in parous women at the post-pregnancy 26 years time point. Conclusions: Pregnancy and parturition may accelerate methylation changes in some CpGs, but slow down or halt methylation changes over time in other CpGs.

Epigenomes doi: 10.3390/epigenomes9030023

Authors: Ana Paula de Souza Vitor Marinho Marcelo Rocha Marques

Epigenetic modifications act as crucial regulators of gene activity and are influenced by both internal and external environmental factors, with diet being the most impactful external factor. On the other hand, cellular metabolism encompasses a complex network of biochemical reactions essential for maintaining cellular function, and it impacts every cellular process. Many metabolic cofactors are critical for the activity of chromatin-modifying enzymes, influencing methylation and the global acetylation status of the epigenome. For instance, dietary nutrients, particularly those involved in one-carbon metabolism (e.g., folate, vitamins B12 and B6, riboflavin, methionine, choline, and betaine), take part in the generation of S-adenosylmethionine (SAM), which represents the main methyl donor for DNA and histone methylation; α-ketoglutarate and ascorbic acid (vitamin C) act, respectively, as a co-substrate and cofactor for Ten-eleven Translocation (TET), which is responsible for DNA demethylation; and metabolites such as Acetyl-CoA directly impact histone acetylation, linking metabolism of the TCA cycle to epigenetic regulation. Further, bioactive compounds, such as polyphenols, modulate epigenetic patterns by affecting methylation processes or targeting epigenetic enzymes. Since diet and nutrition play a critical role in shaping epigenome functions and supporting human health, this review offers a comprehensive update on recent advancements in metabolism, epigenetics, and nutrition, providing insights into how nutrients contribute to metabolic balance, epigenome integrity maintenance and, consequently, disease prevention.

Epigenomes doi: 10.3390/epigenomes9020022

Authors: Kyoko Hatta Masato Kantake Kyoko Tanaka Hirofumi Nakaoka Toshiaki Shimizu Hiromichi Shoji

Background: Somatic symptom disorder (SSD) in children may be influenced by stress reactivity and psychosocial factors. The glucocorticoid receptor (GR), encoded by NR3C1, is a key mediator of stress responses. However, the relationship between NR3C1 methylation and SSD remains unclear. Methods: We analyzed NR3C1 exon 1F methylation in cell-free DNA from saliva in 34 children with SSD and 29 age- and sex-matched controls using bisulfite amplicon sequencing. Psychological assessments included the Beck Depression Inventory-II (BDI-II) and KINDL questionnaires to evaluate associations with methylation patterns. Results: Methylation levels showed age-related differences. In children under 13, CpG sites displayed mixed methylation, and specific sites correlated with KINDL and BDI-II scores. KINDL physical and total well-being scores negatively correlated with CpG30 and positively with CpG35; BDI-II scores negatively correlated with CpG32 and CpG35. In children aged 13 or older, CpG sites showed uniformly high methylation with no correlation to psychological measures. The SSD group showed significantly higher average methylation across the exon 1F region than controls in the older age group. These children also had more cases of orthostatic dysregulation and longer illness duration. Conclusions: This study suggests age-dependent epigenetic regulation of NR3C1 in SSD. While younger children showed CpG-specific correlations with psychological symptoms, older children demonstrated uniformly high methylation and potentially reduced gene expression, potentially reflecting cumulative stress, autonomic dysfunction, and internalizing disorders such as anxiety and depression.

Epigenomes doi: 10.3390/epigenomes9020021

Authors: Nicholas Kim Hong Sun

R-loops, three-stranded RNA-DNA hybrid nucleic acid structures, are recognized for their roles in both physiological and pathological processes. Regulation of R-loops is critical for genome stability as disruption of R-loop homeostasis can lead to aberrant gene expression, replication stress, and DNA damage. Recent studies suggest that the RNA modification, N6-methyladenosine (m6A), can modify R-loops and the writers, erasers, and readers of m6A are involved in the dynamic regulation of R-loops. Here, we discuss the reported functions of various m6A regulatory proteins in relation to R-loops, highlighting their distinct roles in recognizing and modulating the formation, stability, and resolution of these structures. We further examine the functional implications of m6A and R-loop interaction in human diseases, with a particular emphasis on their roles in cancer.

Epigenomes doi: 10.3390/epigenomes9020020

Authors: Gavriel Hadjigavriel Christina Stylianides Evangelos Axarloglou Maria Eleni Manthou Efstratios Vakirlis Paschalis Theotokis Soultana Meditskou Iasonas Dermitzakis

Neurocutaneous syndromes represent a clinically and genetically heterogeneous group of disorders, with tuberous sclerosis complex (TSC), von Hippel–Lindau syndrome (VHL), and ataxia–telangiectasia (A-T) exemplifying some of the most complex entities within this category. These syndromes have traditionally been considered monogenic disorders, caused by germline mutations in tumor suppressor or regulatory genes. However, they exhibit a striking degree of phenotypic variability and divergent clinical trajectories that cannot be fully explained by their underlying genetic alterations alone. Increasingly, epigenetic regulatory mechanisms, such as DNA methylation, histone modifications, chromatin remodeling, and non-coding RNA (ncRNA) activity, are recognized as key modulators of gene expression, cellular differentiation, and tissue-specific function. Disruption of these mechanisms has been implicated in disease pathogenesis, tumorigenesis, and neurodegeneration associated with TSC, VHL, and A-T. Aberrant epigenetic profiles may underlie the observed variability in clinical outcomes, even among individuals with identical mutations. This review consolidates current evidence on the epigenetic landscape of these syndromes, elucidating how these modifications may influence disease behavior and contribute to incomplete genotype–phenotype correlations. By integrating epigenetic insights with known molecular pathways, a more nuanced understanding of disease biology emerges, with potential implications for diagnostic stratification, prognostic assessment, and therapeutic innovation.

Epigenomes doi: 10.3390/epigenomes9020019

Authors: Elena Pozdysheva Vitaly Korchagin Tatiana Rumyantseva Daria Ogneva Vera Zhivotova Irina Gaponova Konstantin Mironov Vasily Akimkin

Background: To date, there are no precise clinical and laboratory methods to accurately predict the onset of fertility decline in women, with chronological age being the ultimate predictor. This has led to increased interest in developing methods to determine biological age, as it provides a more accurate understanding of individual age-related physiological changes. Methods: In this study, we developed a model for estimating biological age based on DNA methylation levels in the ELOVL2, TRIM59, C1orf132, FHL2, and KLF14 genes using pyrosequencing. The model was tested in 64 Russian women, aged 25–39 years, to find an association between epigenetic age, infertility, low anti-Müllerian hormone (AMH) levels, and assisted reproductive technology (ART) failure. Results: The predictive performance of the model was evaluated. The mean absolute deviation of the model was 2.8 years; the mean absolute error was 2.6 years (R2 = 0.95). In the studied cohort, 33% of women exhibited epigenetic age acceleration (EAA), while 45% showed epigenetic age deceleration (EAD). All women with an EAA of ≥3 years (n = 6) had a history of infertility. Conclusions: In this study, no statistically significant associations were observed between EAA/EAD and AMH, body mass index, infertility, or ART failure in women.

Epigenomes doi: 10.3390/epigenomes9020018

Authors: Himani Vaidya Jaroslav Jelinek Jean-Pierre J. Issa

Aging and cancer, though distinct biological processes, share overlapping molecular pathways, particularly in epigenetic regulation. Among these, DNA methylation is central to mediating gene expression, maintaining cellular identity, and regulating genome stability. This review explores how age-associated changes in DNA methylation, characterized by both global hypomethylation and focal hypermethylation, contribute to the emergence of cancer. We discuss mechanisms of DNA methylation drift, the development of epigenetic clocks, and the role of entropy and epigenetic mosaicism, in aging and tumorigenesis. Emphasis is placed on how stochastic methylation errors accumulate in aging cells and lead to epiallelic shifts and gene silencing, predisposing tissues to malignant transformation, even despite recently increased cancer incidences at younger ages. We also highlight the translational potential of DNA methylation-based biomarkers, and therapeutic targets, in age-related diseases. By framing cancer as a disease of accelerated epigenetic aging, this review offers a unifying perspective and calls for age-aware approaches to both basic research and clinical oncology.

Epigenomes doi: 10.3390/epigenomes9020017

Authors: Borivoje Savic Bozidar Savic Svetlana Stanojlovic

This review paper highlights the importance of educating current and future professionals about epigenetic mechanisms and recognizing epigenetics as a crucial model for protection against ionizing radiation. Two basic models for radiation-induced DNA damage are currently in use. The association between mutations and chromosomal aberrations provides a framework for analyzing risks at low radiation doses and exposure to small doses. However, there is no monitoring of epigenetic changes in professionals exposed to low doses of ionizing radiation. Epigenetic events regulate gene activity and expression not only during cell development and differentiation but also in response to environmental stimuli, such as ionizing radiation. Furthermore, the potential occurrence of malignant and hereditary diseases at low doses of ionizing radiation is linearly correlated and is considered a scientifically accepted assumption, despite recognized scientific limitations associated with this assessment. The aim of this review is to integrate novel and intriguing radiobiological paradigms regarding the effects of ionizing radiation on DNA methylation and epigenetic regulation of the DNA molecule. Several hypothesized biological responses to ionizing radiation are examined, linking them to epigenetic mechanisms involved in health risk assessment for professionals. The second part of the review includes published research related to epigenetics, supplementation, and virus reactivation in the context of epigenetic modifications of the DNA molecule. We hypothesize that different cycles lead to changes in the epigenome, which may be associated with the reactivation of certain viruses and the deficiency of specific dietary elements. These findings are linked to minimal deficiencies in vitamin B12 and folic acid, which may contribute to epigenomic changes. This aspect is crucial for the immune status of individuals working in high-risk environments.

Epigenomes doi: 10.3390/epigenomes9020016

Authors: Juliana Ramalho Guimarães José Maria Chagas Viana Filho Naila Francis Paulo de Oliveira

Background: Oral mucositis (OM) is a painful inflammation resulting from chemotherapy. It is dependent on factors such as age, gender, chemotherapy regimen, oral health, immunological and nutritional status, and genetics. Objectives: The aim of the study was to conduct a narrative review to compile studies on the contribution of genetic and epigenetic aspects to the pathogenesis of OM in children with haematological malignancies undergoing chemotherapy treatment. Methods: The literature search was performed in Pubmed, Scopus, Web of Science, Cochrane, Lilacs, and grey literature databases covering articles published since 2010. Results: Twenty-two studies investigating polymorphisms and four studies investigating DNA methylation were included. Polymorphisms in the MTHFR, ABCB1, ABCC2, ABCG2, SLCO1B, miR-1206, miR-3683, CAT, and VDR genes were associated as risk factors for OM and polymorphisms in the TYMS and miR-4268 genes were associated as protective factors. With regard to DNA methylation, associations such as protection or susceptibility to OM have not yet been proven. However, studies have shown that DNMT1 methylation and hypomethylation in total DNA and in the TNF-α gene are associated with recovery of the oral mucosa. Conclusions: Genetic variants are associated with OM in various biological pathways, such as folate metabolism, transport proteins, epigenetic machinery, oxidative stress, and vitamin D metabolism. The DNA methylation profile, which is still poorly understood in the pathogenesis of OM, is associated with mucosal recovery (inflammation and epigenetic machinery). Genetic and epigenetic markers may be tools to indicate a patient’s susceptibility to developing OM, and epigenetic markers may be a target for therapies.

Epigenomes doi: 10.3390/epigenomes9020015

Authors: Julio A. Montero-Del-Toro Angelica A. Serralta-Interian Geovanny I. Nic-Can Mónica Lamas Rodrigo A. Rivera-Solís Beatriz A. Rodas-Junco

Background: The epigenetic regulation of adipogenic differentiation in dental stem cells (DSCs) remains poorly understood, as research has prioritized osteogenic differentiation for dental applications. However, elucidating these mechanisms could enable novel regenerative strategies for soft tissue engineering. Periodontal ligament stem cells (PDLSCs) exhibit notable adipogenic potential, possibly linked to histone 3 acetylation at lysine 9 (H3K9ac); however, the mechanistic role of this modification remains unclear. Methods: To address this gap, we investigated how histone deacetylase inhibitors (HDACis)—valproic acid (VPA, 8 mM) and trichostatin A (TSA, 100 nM)—modulate H3K9ac dynamics, adipogenic gene expression (C/EBPβ and PPARγ-2), and chromatin remodeling during PDLSCs differentiation. Techniques used included quantitative PCR (qPCR), lipid droplet analysis, and chromatin immunoprecipitation followed by qPCR (ChIP-qPCR). Results: TSA-treated cells exhibited increased lipid deposition with smaller lipid droplets compared to VPA-treated cells. Global H3K9ac levels correlated positively with adipogenic progression. VPA induced early upregulation of C/EBPβ and PPARγ-2 (day 7), whereas TSA triggered a delayed but stronger PPARγ-2 expression. ChIP-qPCR analysis revealed significant H3K9ac enrichment at the PPARγ-2 promoter in TSA-treated cells, indicating enhanced chromatin accessibility. Conclusions: These findings demonstrate that H3K9ac-mediated epigenetic remodeling plays a critical role in the adipogenic differentiation of PDLSCs and identifies TSA as a potential tool for modulating this process.

Epigenomes doi: 10.3390/epigenomes9020014

Authors: Alexandria Nyembwe Yihong Zhao Billy A. Caceres Daniel W. Belsky Calen Patrick Ryan Brittany Taylor Morgan T. Morrison Laura Prescott Stephanie Potts-Thompson Arezo Aziz Fisola Aruleba Erica Matute-Arcos Olajide Williams Cindy Crusto Jacquelyn Y. Taylor

Background: Racial discrimination experiences are associated with the activation of stress biology pathways and signs of accelerated biological aging, including alterations in DNA methylation (DNAm). Coping strategies may mitigate stress from racial discrimination and protect against long-term adverse health outcomes. Methods: We conducted a secondary analysis of data from the Intergenerational Impact of Genetic and Psychological Factors on Blood Pressure cohort, an all-African-American sample, to test the hypothesis that social support can protect against accelerated biological aging associated with experiences of racial discrimination. We measured biological aging from saliva DNAm using six epigenetic clocks. Clock values were residualized on participant age and the estimated proportion of epithelial cells contributing to the DNA sample and standardized to M = 0, SD = 1 within the analysis sample. The primary analysis was focused on the second-generation PhenoAge and GrimAge clocks and the third-generation DunedinPACE “speedometer,” which previous studies have linked with racial discrimination. Results: In our sample (n = 234; mean age = 31.9 years; SD = 5.80), we found evidence consistent with our hypothesis in the case of the PhenoAge clock, but not the other clocks. Among mothers who did not seek social support, experiences of racial discrimination were associated with an older PhenoAge (b = 0.26, 95% CI = 0.02–0.50, p = 0.03). However, social-support seeking mitigated this risk; at the highest levels of social support, no adverse consequences of discrimination were observed (interaction b = −0.01, 95% CI = −0.02–−0.00, p = 0.03). Conclusions: The replication of results is needed. Future research should also investigate additional adaptive and maladaptive coping strategies utilized by African American women and mothers to identify protective measures that influence health outcomes.

Epigenomes doi: 10.3390/epigenomes9020013

Authors: Alessia Ronchi Guido Incerti Emanuele De Paoli Speranza Claudia Panico Giovanni Luca Sciabbarrasi Pasquale Termolino Fabrizio Cartenì Mariachiara Langella Maria Luisa Chiusano Stefano Mazzoleni

Background: Previous evidence demonstrated DNA methylation changes in response to stress in plants, showing rapid changes within a limited time frame. Exposure to self-DNA inhibits seedling root elongation, and it was shown that it causes changes in CG DNA methylation in Lactuca sativa. We assessed cytosine methylation changes and associated gene expression patterns in roots of Arabidopsis thaliana Col-0 seedlings exposed to self-DNA for 6 and 24 h. Methods: We used whole genome bisulfite sequencing (WGBS) and RNA-seq analyses to assess genomic cytosine methylation and corresponding gene expression, respectively, on DNA and RNA extracted with commercial kits from roots exposed to self-DNA by an original setup. Fifteen hundred roots replicates, including the control in distilled water, were collected after exposure. Sequencing was performed on a NovaSeq 6000 platform and Ultralow Methyl-Seq System for RNA and DNA WGBS, respectively. Results: Gene expression in roots exposed to self-DNA differed from that of untreated controls, with a total of 305 genes differentially expressed and 87 ontologies enriched in at least one treatment vs. control comparison, and particularly after 24 h of exposure. DNA methylation, particularly in CHG and CHH contexts, was also different, with hyper- and hypomethylation prevailing in treatments vs. controls at 6 h and 24 h, respectively. Differentially expressed genes (DEGs) analysis, Gene Ontology (GO) enrichment analysis, and differentially methylated regions (DMRs) analysis, provided an integrated understanding of the changes associated with self-DNA exposure. Our results suggest differential gene expression associated with DNA methylation in response to self-DNA exposure in A. thaliana roots, enhanced after prolonged exposure. Conclusions: Main functional indications of association between DNA methylation and gene expression involved hypomethylation and downregulation of genes related to nucleotide/nucleoside metabolism (ATP synthase subunit) and cell wall structure (XyG synthase), consistent with previous observations from metabolomics and physiological studies. Further confirmation of these findings will contribute to improving our understanding of the plant molecular response to self-DNA and its implications in stress responses.

Epigenomes doi: 10.3390/epigenomes9020012

Authors: Robert Philibert Steven R. H. Beach Michelle R. vanDellen James A. Mills Jeffrey D. Long

Background: Financial Incentive Treatments (FIT) can be effective in the treatment of smoking. However, weaknesses in current biochemical approaches for assessing smoking cessation may hinder its implementation, particularly for management of long-term smoking cessation. The use of cg05575921 methylation assessments could address some of the shortcomings of current self-report and non-self-report methods, but additional information is needed about the speed of methylation reversion as a function of key clinical and demographic variables. Methods: To better understand those relationships, we analyzed data from 3040 subjects from the National Lung Screening Trial (NLST), including 1552 self-reported quitters. Results: Plotting of the data as a function of time since quitting shows that methylation increases approximately 14%, on average, after at least one full year of cessation with a subsequent slow non-linear increase in methylation over the next 14 years. Least Squares Regression modeling shows strong effects of quit time and a modest, yet significant, effect of body mass index (BMI) on the rate of reversion. Prior cigarette consumption characteristics and sex made modest contributions as well, with the latter largely offset by pre-cessation methylation levels. Race and age were not significant factors in the models. Conclusions: When combined with data from prior studies, these analyses of the long-term reversion of cg05575921 methylation will be informative to those considering FIT approaches to incentivizing reversion of cg05575921 as an index of short- and long-term smoking cessation.

Epigenomes doi: 10.3390/epigenomes9020011

Authors: Pietro Salvatore Carollo Viviana Barra

DNA methylation is an important epigenetic modification with a plethora of effects on cells, ranging from the regulation of gene transcription to shaping chromatin structure. Notably, DNA methylation occurs thanks to the activity of DNA methyltransferases (DNMTs), which covalently add a methyl group to the cytosine in position 5′ in CpG dinucleotides. Different strategies have been developed to study the effects of DNA methylation in cells, involving either DNMTs inhibition (passive DNA demethylation) or the use of Ten-eleven translocation protein (TET) family enzymes, which directly demethylate DNA (active DNA demethylation). In this manuscript, we will briefly cover the most commonly used strategies in the last two decades to achieve DNA demethylation, along with their effects on cells. We will also discuss some of the newest inducible ways to inhibit DNMTs without remarkable side effects, as well as the effect of non-coding RNAs on DNA methylation. Lastly, we will briefly examine the use of DNA methylation inhibition in biomedical research.

Epigenomes doi: 10.3390/epigenomes9020010

Authors: Saida Ibragić Sabina Dahija Erna Karalija

Background: Plants face a wide range of environmental stresses that disrupt growth and productivity. To survive and adapt, they undergo complex metabolic reprogramming by redirecting carbon and nitrogen fluxes toward the biosynthesis of protective secondary metabolites such as phenylpropanoids, flavonoids, and lignin. Recent research has revealed that these stress-induced metabolic processes are tightly regulated by epigenetic mechanisms, including DNA methylation, histone modifications, chromatin remodeling, and non-coding RNAs. Methods: This review synthesizes current findings from studies on both model and crop plants, examining the roles of key epigenetic regulators in controlling secondary metabolism under stress. Special focus is placed on dynamic changes in DNA methylation, histone acetylation, and the action of small RNAs such as siRNAs and miRNAs in transcriptional and post-transcriptional regulation. Results: Evidence indicates that stress triggers rapid and reversible epigenetic modifications that modulate gene expression linked to secondary metabolic pathways. These modifications not only facilitate immediate metabolic responses but can also contribute to stress memory. In some cases, this memory is retained and transmitted to the next generation, influencing progeny stress responses. However, critical knowledge gaps remain, particularly concerning the temporal dynamics, tissue specificity, and long-term stability of these epigenetic marks in crops. Conclusions: Understanding how epigenetic regulation governs secondary metabolite production offers promising avenues to enhance crop resilience and productivity in the context of climate change. Future research should prioritize dissecting the stability and heritability of these modifications to support the development of epigenetically informed breeding strategies.

Epigenomes doi: 10.3390/epigenomes9010009

Authors: Rajesh Melaram Hongmei Zhang James Adefisoye Hasan Arshad

Background: Pollen exposure in early life is shown to be associated with allergy and asthma. DNA methylation (DNAm), an epigenetic marker, potentially reacts to pollen. However, the role of at-birth DNAm between prenatal pollen grain (PPG) exposure and childhood asthma and allergic rhinitis is unknown. Methods: Data in a birth cohort study on the Isle of Wight, UK, were analyzed (n = 236). Newborn DNAm was measured in cord blood or blood spots on Guthrie cards and screened for potential association with PPG exposure using the R package ttScreening. CpGs that passed screening were further assessed for such associations via linear regressions with adjusting covariates included. Finally, DNAm at PPG-associated CpGs were evaluated for their association with asthma and allergic rhinitis using logistic regressions, adjusting for covariates. The impact of cell heterogeneity on the findings was assessed. Statistical significance was set at p < 0.05. Results: In total, 42 CpGs passed screening, with 41 remaining statistically significant after adjusting for covariates and cell types (p < 0.05). High PPG exposure was associated with lower DNAm at cg12318501 (ZNF99, β = −0.029, p = 0.032) and cg00929606 (ADM2, β = −0.023, p = 0.008), which subsequently was associated with decreased odds of asthma (OR = 0.11, 95% CI 0.02–0.53, p = 0.006; OR = 0.14, 95% CI 0.02–1.00, p = 0.049). For rhinitis, cg15790214 (HCG11) was shown to play such a role as a mediator (β = −0.027, p ≤ 0.0001; OR = 0.22, 95% CI 0.07–0.72, p = 0.01). Conclusions: The association of PPG exposure with childhood asthma and allergic rhinitis incidence is potentially mediated by DNAm at birth.

Epigenomes doi: 10.3390/epigenomes9010008

Authors: Roy B. Simons Hieab H. H. Adams Manfred Kayser Athina Vidaki

Background: Epigenetic biomarkers, particularly CpG methylation, are increasingly employed in clinical and forensic settings. However, we still lack a cost-effective, sensitive, medium-scale method for the analysis of hundreds to thousands of user-defined CpGs suitable for minute DNA input amounts (<10 ng). In this study, motivated by promising results in the genetics field, we investigated single-molecule molecular inversion probes (smMIPs) for simultaneous analysis of hundreds of CpGs by using an example set of 514 age-associated CpGs (Zhang model). Methods: First, we developed a novel smMIP design tool to suit bisulfite-converted DNA (Locksmith). Then, to optimize the capture process, we performed single-probe capture for ten selected, representative smMIPs. Based on this pilot, the full smMIP panel was tested under varying capture conditions, including hybridization and elongation temperature, smMIP and template DNA amounts, dNTP concentration and elongation time. Results: Overall, we found that the capture efficiency was highly probe-(and hence, sequence-) dependent, with a heterogeneous coverage distribution across CpGs higher than the 1000-fold range. Considering CpGs with at least 20X coverage, we yielded robust methylation detection with levels comparable to those obtained from the gold standard EPIC microarray analysis (Pearsons’s r: 0.96). Conclusions: The observed low specificity and uniformity indicate that smMIPs in their current form are not compatible with the lowered complexity of bisulfite-converted DNA.

Epigenomes doi: 10.3390/epigenomes9010007

Authors: Ioannis Anestopoulos Ioannis Paraskevaidis Sotiris Kyriakou Louiza Potamiti Dimitrios T. Trafalis Sotiris Botaitis Rodrigo Franco Aglaia Pappa Mihalis I. Panayiotidis

Background: In the present study, we aimed to characterize the cytotoxic efficacy of Zebularine either as a single agent or in combination with various isothiocyanates in an in vitro model consisting of human melanoma (A375, Colo-679) as well as non-tumorigenic immortalized keratinocyte (HaCaT) cells. Methods: In this model, we have evaluated the anti-melanoma effect of Zebularine (in single and combinatorial protocols) in terms of cell viability, apoptotic induction and alterations in ultrastructural chromatin configuration, protein expression levels of DNA methyltransferases (DNMTs) and associated histone epigenetic marks capable of mediating gene expression. Results: Exposure to Zebularine resulted in dose- and time-dependent cytotoxicity through apoptotic induction in malignant melanoma cells, while neighboring non-tumorigenic keratinocytes remained unaffected. A more profound response was observed in combinational protocols, as evidenced by a further decline in cell viability leading to an even more robust apoptotic induction followed by a differential response (i.e., activation/de-activation) of various apoptotic genes. Furthermore, combined exposure protocols caused a significant decrease of DNMT1, DNMT3A and DNMT3B protein expression levels together with alterations in ultrastructural chromatin configuration and protein expression levels of specific histone modification marks capable of modulating gene expression. Conclusions: Overall, we have developed a novel experimental approach capable of potentiating the cytotoxic efficacy of Zebularine against human malignant melanoma cells while at the same time maintaining a non-cytotoxic profile against neighboring non-tumorigenic keratinocyte (HaCaT) cells.

Epigenomes doi: 10.3390/epigenomes9010006

Authors: Risa Mitsuhashi Kiyoshi Sato Hiroyoshi Kawakami

Background/Objectives: Aberrant hypermethylation in the promoter regions of tumor suppressor genes facilitates the pathogenesis and progression of cancer. Therefore, inhibitors targeting DNA methyltransferase (DNMT) have been tested in clinical studies. However, the current monotherapy of DNMT inhibitors shows limited efficacy. Furthermore, the mechanism of action of DNMT inhibitors is DNA replication-dependent. To address these limitations, we developed a novel core–shell-type “epigenetics control (EpC) nanocarrier” that encapsulated decitabine (5-aza-dC) in the PLGA core nanoparticle and hybridized TET1 gene-encoding pDNA on the lipid shell surface. This study aimed to evaluate whether the dual delivery of DNMT inhibitors and pDNA of TET1 could synergistically enhance tumor suppressor gene expression and induce cell cycle arrest and/or apoptosis in cancer cells. Herein, we demonstrate the potential of the EpC carrier in HCT116 human colon cancer cells to upregulate tumor suppressor gene expression and rapidly achieve cell cycle arrest. Methods: PLGA core nanoparticles were prepared by the W/O/W double emulsion method. The formation of core–shell nanoparticles and complexation with pDNA were investigated and optimized by dynamic light scattering, zeta potential measurement, and agarose gel electrophoresis. The cellular uptake and transfection efficiency were measured by confocal laser scanning microscopy and a luciferase assay, respectively. The expression of p53 protein was detected by Western blotting. The anti-tumor effects of the EpC nanocarrier were evaluated by cell cycle analysis and an apoptosis assay. Results: The EpC nanocarrier delivered the DNMT inhibitor and TET gene-encoding pDNA into HCT116 cells. It promoted the expression of the tumor suppressor protein p53 and induced rapid cell cycle arrest in the G2/M phase in HCT116 cells. Conclusions: Our findings suggest that the dual-targeting of DNMT and TET enzymes effectively repairs aberrant DNA methylation and induces growth arrest in cancer cells, and the dual-targeting strategy may contribute to the advancement of epigenetic cancer therapy.

Epigenomes doi: 10.3390/epigenomes9010005

Authors: Alexandra A. Baumann Zholdas Buribayev Olaf Wolkenhauer Amankeldi A. Salybekov Markus Wolfien

Genomic and epigenomic instability are defining features of cancer, driving tumor progression, heterogeneity, and therapeutic resistance. Central to this process are epigenetic echoes, persistent and dynamic modifications in DNA methylation, histone modifications, non-coding RNA regulation, and chromatin remodeling that mirror underlying genomic chaos and actively influence cancer cell behavior. This review delves into the complex relationship between genomic instability and these epigenetic echoes, illustrating how they collectively shape the cancer genome, affect DNA repair mechanisms, and contribute to tumor evolution. However, the dynamic, context-dependent nature of epigenetic changes presents scientific and ethical challenges, particularly concerning privacy and clinical applicability. Focusing on lung cancer, we examine how specific epigenetic patterns function as biomarkers for distinguishing cancer subtypes and monitoring disease progression and relapse.

Epigenomes doi: 10.3390/epigenomes9010004

Authors: Alexander V. Sergeev Daniil P. Malyshev Adelya I. Genatullina Galina V. Pavlova Elizaveta S. Gromova Maria I. Zvereva

Background: The methylation of cytosine residues at CpG sites within the O6-methylguanine-DNA methyltransferase (MGMT) promoter is a key biomarker in glioblastoma therapy. The MGMT promoter (MGMTp) contains multiple guanine-rich sequences capable of folding into G-quadruplexes (G4s), but their relevance for MGMTp methylation is poorly understood. Objectives: Our study explores the impact of potential G-quadruplex-forming sequences (PQS) in the MGMT promoter CpG island on the activity of de novo DNA methyltransferase Dnmt3a. Additionally, we investigate their influence on the accuracy of methylation pattern detection using nanopore sequencing. Methods: Nanopore sequencing was employed to analyze the methylation of 94 clinically significant CpG sites in the human MGMTp using an in vitro de novo methylation system. Circular dichroism spectroscopy was used to identify G4 structures within the MGMTp CpG island. Interactions between the catalytic domain of Dnmt3a and the PQS from the MGMTp were examined by biolayer interferometry. Results: Guanine-rich DNA strands of the PQSs in the MGMTp were hypomethylated, while the complementary cytosine-rich strands were methylated by DNA methyltransferase Dnmt3a with higher efficiency. The accuracy of detecting modified bases in the PQS was significantly lower compared to surrounding sequences. Single-stranded guanine-rich DNA sequences from the MGMTp exhibited strong binding to Dnmt3a-CD, with an affinity approximately 10 times higher than their cytosine-rich complements (Kd = 3 × 10−8 M and 3 × 10−7 M, respectively). By binding to Dnmt3a, G4-forming oligonucleotides from MGMTp effectively inhibited the methylation reaction (IC50 6 × 10−7 M). Conclusions: The obtained data indicate the role of PQSs in establishing de novo methylation of the MGMT promoter. They also highlight the challenges of sequencing guanine-rich regions and the impact of specific de novo methylation patterns on clinical data interpretation.

Epigenomes doi: 10.3390/epigenomes9010003

Authors: Iasonas Dermitzakis Stella Aikaterini Kyriakoudi Sofia Chatzianagnosti Despoina Chatzi Efstratios Vakirlis Soultana Meditskou Maria Eleni Manthou Paschalis Theotokis

The skin, the largest organ of the human body, plays numerous essential roles, including protection against environmental hazards and the regulation of body temperature. The processes of skin homeostasis and ageing are complex and influenced by many factors, with epigenetic mechanisms being particularly significant. Epigenetics refers to the regulation of gene expression without altering the underlying DNA sequence. The dynamic nature of the skin, characterized by constant cellular turnover and responsiveness to environmental stimuli, requires precise gene activity control. This control is largely mediated by epigenetic modifications such as DNA methylation, histone modification, and regulation by non-coding RNAs. The present review endeavours to provide a comprehensive exploration and elucidation of the role of epigenetic mechanisms in regulating skin homeostasis and ageing. By integrating our current knowledge of epigenetic modifications with the latest advancements in dermatological research, we can gain a deeper comprehension of the complex regulatory networks that govern skin biology. Understanding these mechanisms also presents promising avenues for therapeutic interventions aimed at improving skin health and mitigating age-related skin conditions.

Epigenomes doi: 10.3390/epigenomes9010002

Authors: Kajetan Kiełbowski Estera Bakinowska Anna Gorący-Rosik Karolina Figiel Roksana Judek Jakub Rosik Paweł Dec Andrzej Modrzejewski Andrzej Pawlik

Rheumatoid arthritis (RA) is a progressive autoimmune disease leading to structural and functional joint damage and, eventually, to physical disability. The pathogenesis of the disease is highly complex and involves interactions between fibroblast-like synoviocytes (FLSs) and immune cells, which stimulate the secretion of pro-inflammatory factors, leading to chronic inflammation. In recent years, studies have demonstrated the importance of epigenetics in RA. Specifically, epigenetic alterations have been suggested to serve as diagnostic and treatment biomarkers, while epigenetic mechanisms are thought to be involved in the pathogenesis of RA. Epigenetic regulators coordinate gene expression, and in the case of inflammatory diseases, they regulate the expression of a broad range of inflammatory molecules. In this review, we discuss current evidence on the involvement of DNA and RNA methylation in RA.

Epigenomes doi: 10.3390/epigenomes9010001

Authors: Robert Philibert Steven R. H. Beach Allan M. Andersen

Background: Heavy alcohol consumption (HAC) has a profound adverse effect on human health. Unfortunately, there is a relative lack of tools that are easily implementable in clinical settings and that can be used to supplement self-reporting in the diagnosis and management of HAC. In part, this paucity is due to limitations of currently available biological measures and a mismatch between available biological measures and the needs of clinicians managing HAC. Objectives: We first review the pros and cons of existing biological measures. Next, we review the underlying theory and the performance characteristics of two recently developed methylation-sensitive digital PCR (MSdPCR) assays, referred to as the Alcohol T Score (ATS) and ZSCAN25, for the assessment of chronic and recent HAC, respectively. Finally, we outline a paradigm for improving the clinical diagnosis and management of alcohol use disorders by utilizing these new markers of alcohol consumption. Conclusions: We conclude that further studies to understand the test performance characteristics of each of these epigenetic tools in larger, diverse populations are in order.

Epigenomes doi: 10.3390/epigenomes8040046

Authors: Nanzha Abi Alexandra Young Pradeep Tiwari Junyu Chen Chang Liu Qin Hui Kaku So-Armah Matthew S. Freiberg Amy C. Justice Ke Xu Marta Gwinn Vincent C. Marconi Yan V. Sun

Background/Objectives: People with HIV (PWH) on antiretroviral therapy (ART) often gain weight, which increases their risk of type 2 diabetes and cardiovascular disease. The role of DNA methylation (DNAm) markers in obesity among PWH is understudied. This research explores the relationship between body mass index (BMI) and epigenetic patterns to better understand and manage obesity-related risks in PWH. Methods: We conducted an epigenome-wide association study (EWAS) on 892 African American male PWH from the Veterans Aging Cohort Study, examining BMI associations with DNAm using linear mixed models, adjusting for covariates, including soluble CD14. We compared our results with BMI-associated DNAm markers from non-HIV individuals and developed a methylation risk score (MRS) for BMI using machine learning and a cross-validation approach. Results: We identified four epigenome-wide significant CpG sites, including one in the RAP1B gene, indicating shared and unique BMI-related epigenetic markers between PWH and non-HIV individuals. The constructed BMI MRS explained approximately 19% of the BMI variance in PWH. Conclusions: DNAm markers and MRS are significantly linked to BMI in PWH, suggesting shared and distinct molecular mechanisms with non-HIV populations. These insights could lead to targeted interventions to reduce cardiometabolic disease risks in PWH under ART.

Epigenomes doi: 10.3390/epigenomes8040045

Authors: Gustavo Tinoco Gustavo Russo Rogério Curi Marcelo Vicari Paloma Melo Isabella Souza Juliana Torrecilhas Philipe Moriel Welder Baldassini Luis Chardulo Otávio Neto Guilherme Pereira

Background/Objectives: Early weaning management followed by energy supplementation can lead to metabolic alterations in the calf that exert long-term effects on the animal’s health and performance. It is believed that the main molecular basis underlying these metabolic adaptations are epigenetic mechanisms that regulate, activate, or silence genes at different stages of development and/or in response to different environmental stimuli. However, little is known about postnatal metabolic programming in Bos indicus. Therefore, this study aimed to compare the DNA methylation profile of Nellore animals submitted to conventional and early weaning and to correlate the findings with genes differentially expressed in the Longissimus thoracis skeletal muscle of Bos indicus cattle. Methods: For this, we used Reduced Representation Bisulfite Sequencing (RRBS) and RNA-Sequencing techniques to prospect differentially methylated genes (DMGs). Results: A total of 481 differentially methylated regions were identified, with 52% (250) being hypermethylated and 48% (231) hypomethylated. Functional enrichment analysis of 53 differentially methylated and differentially expressed genes was performed. The main enriched terms and pathways were associated with 3′-5′-cyclic adenosine monophosphate (cAMP) signaling, which presents the upregulated adenylate cyclase 3 (ADCY3) gene and significatively hypomethylated in the promoter region. Alterations in cAMP signaling are involved in numerous processes, many of them related to lipid metabolism. The relative differential expression of key genes of this pathway demonstrates the relationship between cAMP signaling and de novo lipogenesis. Conclusions: These findings suggest an important role of postnatal metabolic programming through DNA methylation mechanisms in determining fat deposition in beef.

Epigenomes doi: 10.3390/epigenomes8040044

Authors: Yoichi Takenaka Osaka Twin Research Group Osaka Twin Research Group Mikio Watanabe

Background/Objectives: The dynamic interaction between genomic DNA, epigenetic modifications, and phenotypic traits was examined in identical twins. Environmental perturbations can induce epigenetic changes in DNA methylation, influencing gene expression and phenotypes. Although DNA methylation mediates gene-environment correlations, the quantitative effects of external factors on DNA methylation remain underexplored. This study aimed to quantify these effects using a novel approach. Methods: A cohort study was conducted on healthy monozygotic twins to evaluate the influence of environmental stimuli on DNA methylation. We developed the Environmental Factor Index (EFI) to identify methylation sites showing statistically significant changes in response to environmental stimuli. We analyzed the identified sites for associations with disorders, DNA methylation markers, and CpG islands. Results: The EFI identified methylation sites that exhibited significant associations with genes linked to various disorders, particularly cancer. These sites were overrepresented on CpG islands compared to other genomic features, highlighting their regulatory importance. Conclusions: The EFI is a valuable tool for understanding the molecular mechanisms underlying disease pathogenesis. It provides insights into the development of preventive and therapeutic strategies and offers a new perspective on the role of environmental factors in epigenetic regulation.

Epigenomes doi: 10.3390/epigenomes8040043

Authors: Qihua Tan Hikmat Alo Marianne Nygaard Mette Sørensen Alisa Saleh Jonas Mengel-From Kaare Christensen

We aimed to explore the age-dependent epigenetic variability on the X-chromosome with consideration of X-chromosome inactivation by applying a sex-stratified regression analysis to DNA methylation array data on X-linked CpGs in aging identical twins. We found 13 X-linked CpGs showing age-related significant increase in variability in males (FDR < 0.05) but none in females. In females, we found a significantly higher proportion of CpGs showing increased variability with age among nominally significant (p < 0.05) CpGs under inactivation, but not among CpGs escaping inactivation. Survival analysis showed a slight trend of correlation by directional change in the variable CpGs with mortality in males. Compared with females, the male X-chromosome can be more vulnerable to epigenetic instability during aging.

Epigenomes doi: 10.3390/epigenomes8040042

Authors: Hong-Yeoul Ryu

Cryptic transcription refers to the unintended expression of non-canonical sites within the genome, producing aberrant RNA and proteins that may disrupt cellular functions. In this opinion piece, I will explore the role of histone modifications in modulating cryptic transcription and its implications for gene expression and cellular integrity, particularly with a focus on H3K36 and H3K4 methylation marks. H3K36 tri-methylation plays a crucial role in maintaining chromatin integrity by facilitating the recruitment of the Rpd3S histone deacetylase (HDAC) complex, which helps restore closed chromatin states following transcription and prevents cryptic initiation within gene bodies. In parallel, crosstalk between H3K4 di-methylation and histone ubiquitylation and sumoylation is critical for recruiting the Set3 HDAC complex, which maintains low histone acetylation levels in gene bodies and further suppresses cryptic transcription. Therefore, by elucidating these regulatory mechanisms, this opinion highlights the intricate interplay of histone modifications in preserving transcriptional fidelity and suggests potential pathways for future research to develop novel therapies for age-related disorders and other diseases associated with dysregulated gene expression.

Epigenomes doi: 10.3390/epigenomes8040041

Authors: Peiyi Liu Juliette Jacques Chang-Il Hwang

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most lethal malignancies, characterized by its aggressive progression and dismal prognosis. Advances in epigenetic profiling, specifically DNA methylation analysis, have significantly deepened our understanding of PDAC pathogenesis. This review synthesizes findings from recent genome-wide DNA methylation studies, which have delineated a complex DNA methylation landscape differentiating between normal and cancerous pancreatic tissues, as well as across various stages and molecular subtypes of PDAC. These studies identified specific differentially methylated regions (DMRs) that not only enhance our grasp of the epigenetic drivers of PDAC but also offer potential biomarkers for early diagnosis and prognosis, enabling the customization of therapeutic approaches. The review further explores how DNA methylation profiling could facilitate the development of subtype-tailored therapies, potentially improving treatment outcomes based on precise molecular characterizations. Overall, leveraging DNA methylation alterations as functional biomarkers holds promise for advancing our understanding of disease progression and refining PDAC management strategies, which could lead to improved patient outcomes and a deeper comprehension of the disease’s underlying biological mechanisms.

Epigenomes doi: 10.3390/epigenomes8040040

Authors: Hui Li Jialiang Kan Chunxiao Liu Qingsong Yang Jing Lin Xiaogang Li

Background: Flowers are important plant organs, and their development is correlated with yield in woody fruit trees. For Pyrus pyrifolia cultivar ‘Sucui 1’, the research on how DNA methylation accurately regulates the expression of TFs and affects the specific regulatory mechanism of flower bud wizening will help reduce wizened buds. Methods: Here, the DNA methylomes and transcriptomes of two types of flower buds from the Pyrus pyrifolia cultivar ‘Sucui 1’ were compared. Results: 320 differentially expressed transcription factors (TFs), in 43 families, were obtained from the wizened bud transcriptome versus the normal bud transcriptome. Most were members of the AP2/ERF, bHLH, C2H2, CO-like, MADS, MYB, and WRKY families, which are involved in flower development. As a whole, the methylation level of TFs in the ‘Sucui 1’ genome increased once flower bud wizening occurred. A cytosine methylation analysis revealed that the methylation levels of the same gene regions in TFs from two kinds of buds were similar. However, differentially methylated regions were found in gene promoter sequences. The combined whole-genome bisulfite sequencing and RNA-Seq analyses revealed 162 TF genes (including 164 differentially methylated regions) with both differential expression and methylation differences between the two flower bud types. Among them, 126 were classified as mCHH-type methylation genes. Furthermore, the transcriptional down regulation of PpbHLH40, PpERF4, PpERF061, PpLHW, PpMADS6, PpZF-HD11, and PpZFP90 was accompanied by increased DNA methylation. However, PpbHLH130, PpERF011, and PpMYB308 displayed the opposite trend. The expression changes for these TFs were negatively correlated with their methylation states. Conclusions: Overall, our results offer initial experimental evidence of a correlation between DNA methylation and TF transcription in P. pyrifolia in response to bud wizening. This enriched our understanding of epigenetic modulations in woody trees during flower development.

Epigenomes doi: 10.3390/epigenomes8040039

Authors: Shengyuan Zeng Karl Ekwall

(1) Background: Quiescent cells are those that have stopped dividing and show strongly reduced levels of gene expression during dormancy. In response to appropriate signals, the cells can wake up and start growing again. Many histone modifications are regulated in quiescence, but their exact functions remain to be determined. (2) Methods: Here, we map the different histone modifications, H3K4me3, H3K9ac, H3K9me2, and H3K9me3, and the histone variant H2A.Z, comparing vegetative and quiescent fission yeast (S. pombe) cells. We also map histone H3 as a control and RNA polymerase II (phosphorylated at S2 and S5) to enable comparisons of their occupancies within genes. We use ChIP-seq methodology and several different bioinformatics tools. (3) Results: The histone modification mapping data show that H3K4me3 changes stand out as being the most significant. Changes in occupancy of histone variant H2A.Z were also significant, consistent with earlier studies. Regarding gene expression changes in quiescence, we found that changes in mRNA levels were associated with changes in occupancy of RNA polymerase II (S2 and S5). Analysis of quiescence genes showed that increased H3K4me3 levels and RNA polymerase II occupancy were super-significant in a small set of core quiescence genes that are continuously upregulated during dormancy. We demonstrate that several of these genes were require Set1C/COMPASS activity for their strong induction during quiescence. (4) Conclusions: Our results imply that regulation of gene expression in quiescent cells involves epigenome changes with a key role for H3K4me3 in regulation of RNA polymerase II activity, and that different gene activation mechanisms control early and core quiescence genes. Thus, our data give further insights into important epigenome changes in quiescence using fission yeast as an experimental model.

Epigenomes doi: 10.3390/epigenomes8040038

Authors: Andrea Stoccoro Martina Lari Lucia Migliore Fabio Coppedè

Background/Objectives: One-carbon metabolism is a critical pathway for epigenetic mechanisms. Circulating biomarkers of one-carbon metabolism have been associated with changes in nuclear DNA methylation levels in individuals affected by age-related diseases. More and more studies are showing that even mitochondrial DNA (mtDNA) could be methylated. In particular, methylation of the mitochondrial displacement (D-loop) region modulates the gene expression and replication of mtDNA and, when altered, can contribute to the development of human illnesses. However, no study until now has demonstrated an association between circulating biomarkers of one-carbon metabolism and D-loop methylation levels. Methods: In the study presented herein, we searched for associations between circulating one-carbon metabolism biomarkers, including folate, homocysteine, and vitamin B12, and the methylation levels of the D-loop region in DNA obtained from the peripheral blood of 94 elderly voluntary subjects. Results: We observed a positive correlation between D-loop methylation and vitamin B12 (r = 0.21; p = 0.03), while no significant correlation was observed with folate (r = 0.02; p = 0.80) or homocysteine levels (r = 0.02; p = 0.82). Moreover, D-loop methylation was increased in individuals with high vitamin B12 levels compared to those with normal vitamin B12 levels (p = 0.04). Conclusions: This is the first study suggesting an association between vitamin B12 circulating levels and mtDNA methylation in human subjects. Given the potential implications of altered one-carbon metabolism and mitochondrial epigenetics in human diseases, a deeper understanding of their interaction could inspire novel interventions with beneficial effects for human health.

Epigenomes doi: 10.3390/epigenomes8040037

Authors: Jenny van Dongen Charles E. Breeze Twinning Genetics Consortium Twinning Genetics Consortium

Background/Objectives: Human identical twins are born at a rate of 3–4 per 1000 live births. Many other mammals also occasionally produce monozygotic twins, referred to as sporadic polyembryony. The underlying mechanisms are unknown. Through epigenome-wide association studies (EWAS), we identified a robust DNA methylation signature in somatic tissues from human monozygotic (MZ) twins, comprising 834 differentially methylated positions (MZ-DMPs). The results point to a connection between monozygotic twinning and early genome programming and enable new angles to study monozygotic twinning. Methods: The mammalian methylation array (MMA) measures 38,608 CpGs focusing on regions that are well-conserved across many mammalian species, allowing for pan-mammalian comparative epigenomic studies. Here, we successfully map human MZ-DMPs to probes of the mammalian methylation array across 157 mammalian genomes. Results: As expected, based on the modest probe overlap between Illumina 450k/EPIC and mammalian methylation array probes, only a subset of MZ-DMPs reside in conserved regions covered by the mammalian methylation array. These include probes mapping to NPAS3, KLHL35, CASZ1, and ATP2B2. Re-analysis restricting the original EWAS in humans to conserved MMA regions yielded additional MZ-DMPs, suggesting that more loci may be detected by application of the mammalian array to monozygotic twins. Conclusions: In conclusion, the mammalian methylation array may prove to be a promising platform to study whether a shared DNA methylation signature of sporadic polyembryony exists across diverse mammalian species. This may potentially point to shared underlying mechanisms.

Epigenomes doi: 10.3390/epigenomes8030036

Authors: Tingyu Fan Jianlian Xie Guo Huang Lili Li Xi Zeng Qian Tao

Many human diseases, such as malignant tumors and neurological diseases, have a complex pathophysiological etiology, often accompanied by aberrant epigenetic changes including various histone modifications. Plant homologous domain finger protein 8 (PHF8), also known as lysine-specific demethylase 7B (KDM7B), is a critical histone lysine demethylase (KDM) playing an important role in epigenetic modification. Characterized by the zinc finger plant homology domain (PHD) and the Jumonji C (JmjC) domain, PHF8 preferentially binds to H3K4me3 and erases repressive methyl marks, including H3K9me1/2, H3K27me1, and H4K20me1. PHF8 is indispensable for developmental processes and the loss of PHF8 enzyme activity is linked to neurodevelopmental disorders. Moreover, increasing evidence shows that PHF8 is highly expressed in multiple tumors as an oncogenic factor. These findings indicate that studying the role of PHF8 will facilitate the development of novel therapeutic agents by the manipulation of PHF8 demethylation activity. Herein, we summarize the current knowledge of PHF8 about its structure and demethylation activity and its involvement in development and human diseases, with an emphasis on nervous system disorders and cancer. This review will update our understanding of PHF8 and promote the clinical transformation of its predictive and therapeutic value.

Epigenomes doi: 10.3390/epigenomes8030035

Authors: Andromachi Katsanou Charilaos Kostoulas Evangelos Liberopoulos Agathocles Tsatsoulis Ioannis Georgiou Stelios Tigas

Retrotransposons are invasive genetic elements, which replicate by copying and pasting themselves throughout the genome in a process called retrotransposition. The most abundant retrotransposons by number in the human genome are Alu and LINE-1 elements, which comprise approximately 40% of the human genome. The ability of retrotransposons to expand and colonize eukaryotic genomes has rendered them evolutionarily successful and is responsible for creating genetic alterations leading to significant impacts on their hosts. Previous research suggested that hypomethylation of Alu and LINE-1 elements is associated with global hypomethylation and genomic instability in several types of cancer and diseases, such as neurodegenerative diseases, obesity, osteoporosis, and diabetes mellitus (DM). With the advancement of sequencing technologies and computational tools, the study of the retrotransposon’s association with physiology and diseases is becoming a hot topic among researchers. Quantifying Alu and LINE-1 methylation is thought to serve as a surrogate measurement of global DNA methylation level. Although Alu and LINE-1 hypomethylation appears to serve as a cellular senescence biomarker promoting genomic instability, there is sparse information available regarding their potential functional and biological significance in DM. This review article summarizes the current knowledge on the involvement of the main epigenetic alterations in the methylation status of Alu and LINE-1 retrotransposons and their potential role as epigenetic markers of global DNA methylation in the pathogenesis of DM.

Epigenomes doi: 10.3390/epigenomes8030034

Authors: Lara Saftić Martinović Tea Mladenić Dora Lovrić Saša Ostojić Sanja Dević Pavlić

Infertility is a complex condition caused by a combination of genetic, environmental, and lifestyle factors. Recent advances in epigenetics have highlighted the importance of epigenetic changes in fertility regulation. This review aims to provide a comprehensive overview of the epigenetic mechanisms involved in infertility, with a focus on DNA methylation, histone modification, and non-coding RNAs. We investigate the specific epigenetic events that occur during gametogenesis, with a focus on spermatogenesis and oogenesis as distinct processes. Furthermore, we investigate how environmental factors such as diet, stress, and toxin exposure can influence these epigenetic changes, potentially leading to infertility. The second part of the review explores epigenetic changes as therapeutic targets for infertility. Emerging therapies that modulate epigenetic marks present promising opportunities for fertility restoration, particularly in spermatogenesis. By summarizing current research findings, this review emphasizes the importance of understanding epigenetic contributions to infertility. Our discussion aims to lay the groundwork for future research directions and clinical applications in reproductive health.

Epigenomes doi: 10.3390/epigenomes8030033

Authors: Brandon A. Boone Cristy P. Mendoza Noah J. Behrendt Steven E. Jacobsen

Proteins are localized and concentrated at cellular and genomic locations for specific and efficient functions. Efforts to understand protein accumulation in eukaryotic organisms have primarily focused on multivalent interactions between intrinsically disordered regions (IDRs) as mediators of protein condensation. We previously showed that α-crystalline domain (ACD) proteins 15 (ACD15) and 21 (ACD21) were required for multimerization and the accumulation of gene-silencing methyl-CpG-binding domain protein 6 (MBD6) at chromocenters in Arabidopsis thaliana. Here, we demonstrate that ACDs and IDRs can act as parallel mechanisms, facilitating higher-order MBD6 assemblies. Using human IDRs known to be important for protein accumulation, we replicated and enhanced the accumulation of MBD6 at chromocenters. In addition, IDRs fused to MBD6 could substitute for ACD function and partially reconstitute the MBD6 gene-silencing function. However, the accumulation of MBD6 by IDRs still required ACD15 and ACD21 for full effect. These results establish that ACD-mediated protein accumulation is a mechanism that can function similarly to and together with IDR-mediated mechanisms.

Epigenomes doi: 10.3390/epigenomes8030032

Authors: Pawel Nowialis Julian Tobon Katarina Lopusna Jana Opavska Arshee Badar Duo Chen Reem Abdelghany Gene Pozas Jacob Fingeret Emma Noel Alberto Riva Hiroshi Fujiwara Alexander Ishov Rene Opavsky

Cytosine methylation contributes to the regulation of gene expression and normal hematopoiesis in mammals. It is catalyzed by the family of DNA methyltransferases that include DNMT1, DNMT3A, and DNMT3B. Peripheral T–cell lymphomas (PTCLs) represent aggressive mature T–cell malignancies exhibiting a broad spectrum of clinical features with poor prognosis and inadequately understood molecular pathobiology. To better understand the molecular landscape and identify candidate genes involved in disease maintenance, we profiled DNA methylation and gene expression of PTCLs. We found that the methylation patterns in PTCLs are deregulated and heterogeneous but share 767 hypo- and 567 hypermethylated differentially methylated regions (DMRs) along with 231 genes up- and 91 genes downregulated in all samples, suggesting a potential association with tumor development. We further identified 39 hypomethylated promoters associated with increased gene expression in the majority of PTCLs. This putative oncogenic signature included the TRIP13 (thyroid hormone receptor interactor 13) gene whose genetic and pharmacologic inactivation inhibited the proliferation of T–cell lines by inducing G2-M arrest and apoptosis. Our data thus show that human PTCLs have a significant number of recurrent methylation alterations that may affect the expression of genes critical for proliferation whose targeting might be beneficial in anti-lymphoma treatments.