Epigenomes

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.

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 (M_w): low M_w polysaccharide chains drive stimulatory processes such as inflammation and angiogenesis, whereas high M_w 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.

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.