Search Results (478)

Mitochondrial DNA (mtDNA) mutations are associated with a diverse spectrum of diseases and pose a significant threat to human health. Despite their importance as therapeutic targets, the unique structural and electrochemical properties of mitochondria—most notably the impermeable inner mitochondrial membrane and the high membrane potential—present formidable challenges for the targeted delivery of therapeutic agents. Currently, there are no approved curative treatments for patients harboring pathogenic mtDNA mutations. In this review, we discuss recent advancements in gene therapy for mitochondrial genome-related disorders, with a particular focus on allotopic expression of mtDNA-encoded genes and mitochondrial genome editing technologies. We conclude that allotopic expression currently stands as the most promising approach for near-term clinical implementation. But we also pay great attention to programmable nucleases and base editors utilizing RNA-independent DNA recognition which are evolving with remarkable speed. Full article

Background: The transfer of a nucleus from one oocyte to another offers patients harbouring high levels of mitochondrial DNA mutation and sufferers of frequent fertilisation failure or early embryonic arrest the potential to have healthy children. However, a small amount of mtDNA is carried over with the nucleus as the transfer takes place. Consequently, we still need to distinguish between the effects of the carryover and the transfer of a nucleus itself from a mature oocyte. Methods: To overcome this, we analysed a series of hatching stage blastocysts generated using metaphase II spindle transfer and mitochondrial supplementation. The latter approach also introduces a small amount of mtDNA into the oocyte as fertilisation takes place. For both manipulations, an autologous approach was used to overcome the effects of third-party transfer. Results: We then compared the changes in global gene expression between the two groups. We found that the nuclear transfer process affected a number of gene networks and pathways. These included metabolic, cell cycle, inflammatory and immune, and epigenetic responses. A comparison with earlier stage blastocysts did not suggest that the cause was due to developmental delay. Conclusions: Critically, these changes could affect offspring health and well-being as is the case following somatic cell nuclear transfer. Full article

Aristolochic acid (AA), a naturally occurring compound found in Aristolochia plants, is a well-established nephrotoxin and Group 1 carcinogen. Emerging evidence suggests a potential link between AA exposure and hepatocellular carcinoma (HCC), one of the leading causes of cancer-related mortality worldwide. This review critically evaluates current knowledge on AA’s hepatic metabolism, its formation of persistent DNA adducts, and the induction of inflammatory responses in the liver. Based on preclinical and indirect human evidence, we propose a working hypothesis that AA may contribute to hepatocarcinogenesis through a dual mechanism: genotoxic (primarily via H-ras and p53 mutations resulting from AA-DNA adducts) and non-genotoxic (via chronic inflammation involving IL-6, TNF-α, and NF-κB activation, as well as epithelial–mesenchymal transition). We note, however, that these mechanisms remain to be validated in human cohorts and do not yet establish causality. Recent studies have identified novel mechanisms, including PDK4-mediated mitochondrial dysfunction, ferroptosis inhibition via p53 hijacking, and ARID1A deficiency as a susceptibility factor. A recent meta-analysis quantified a significantly increased risk of liver cancer following AA exposure in epidemiological studies. While direct causal evidence in humans remains limited, the high mutational burden observed in AA-exposed liver tissues warrants caution. Nevertheless, the primary public health priority pertains to the prevention of AA exposure. Further epidemiological and mechanistic studies are urgently needed. Full article

Transmitochondrial cybrid technology is a key approach for elucidating the effects of mitochondrial DNA (mtDNA) mutations in defined nuclear genetic backgrounds and for studying nuclear–mitochondrial interactions. However, its application is limited by the availability of suitable recipient cell lines and by technically demanding enucleation procedures. We report three advances in cybrid technology: (1) enucleation using mitomycin C, a widely used agent for generating feeder layers in stem cell culture, which does not depend on cell attachment and provides a gentler alternative to actinomycin D; (2) selection of cybrids using mitochondrial uncouplers, which can reduce background survival of non-cybrid cells; and (3) cryopreservation of enucleated donor cells in liquid nitrogen, preserving fusion competence and increasing experimental flexibility. Additionally, we validate newly developed mtDNA-free (ρ⁰) derivatives of HCT116, HT1080, and U2OS cell lines as recipients for cybrid generation. These advances facilitated donor cell preparation, improved cybrid selection, and enhanced experimental flexibility, including the demonstration of preserved fusion competence of enucleated HeLa cells after 10 years of cryostorage. The ρ⁰ derivatives of HCT116, HT1080, and U2OS cells were confirmed as effective recipients. Together, these improvements enhance the efficiency and accessibility of transmitochondrial cybrid technology and are expected to facilitate its broader application. Full article

Mitochondria have emerged as critical regulators of cancer biology, transcending their classical role as cellular powerhouses to orchestrate complex metabolic, signaling, and survival pathways essential for tumorigenesis. This review examines the multifaceted role of mitochondria in cancer, integrating initial discoveries with recent advances from recent studies. We explore how mitochondrial DNA mutations, metabolic reprogramming, and alterations in mitochondrial dynamics contribute to malignant transformation, tumor progression, and therapeutic resistance. Mitochondrial dysfunction, long considered a consequence of the Warburg effect, is now recognized as an active driver of oncogenesis through retrograde signaling, oxidative stress modulation, and tumor microenvironment remodeling. The review highlights emerging therapeutic strategies targeting mitochondrial metabolism, including inhibitors of oxidative phosphorylation, mitochondrial-targeted drugs, and approaches exploiting metabolic vulnerabilities. Understanding the complex interplay between mitochondrial function and cancer biology provides a foundation for developing novel diagnostic biomarkers and precision oncology approaches. Full article

Serving as central signalling organelles and hubs of metabolism, mitochondria are essential for cellular homeostasis. Mitochondrial disease can arise from mutations to nuclear or mitochondrial DNA, which result in disruptions to normal mitochondrial function. This generates a suite of rare disorders which are multi-system and often fatal. Variable tissue distribution of mitochondria, alongside a high degree of heterogeneity in associated phenotype, has resulted in an inadequate understanding and characterisation of mitochondrial disease. Addressing this issue is therefore crucial for better clinical management and patient outcomes. Cholesterol dyshomeostasis is a potential pathological hallmark of numerous mitochondrial diseases. Cholesterol is an essential lipid and bioactive compound involved in numerous mitochondrial and cellular processes. A growing number of studies have reported perturbations to cholesterol biosynthesis, cholesterol import, and cholesterol ratios in cell and animal models and individuals with mitochondrial disease, suggesting it could be a unifying feature of these disparate and variable disorders. This review summarises the current experimental evidence for the role of cholesterol dyshomeostasis in mitochondrial disease. It will further discuss reports of statin intolerance, generally attributed to off-target action on mitochondrial structures, in the context of this evidence. Ultimately, the necessity of further integrative clinical and experimental studies exploring the potential of cholesterol dyshomeostasis as a pathological hallmark of mitochondrial disease will be highlighted. Full article

The genus Hydrochara (Coleoptera: Hydrophilidae) comprises large-bodied water beetles associated with shallow, well-vegetated freshwater habitats and is characterised by considerable taxonomic complexity. While Hydrochara caraboides is relatively well studied in western and central Europe, lineage diversity and species boundaries within the genus remain poorly resolved in eastern and south-eastern Europe. This study uses an integrative approach combining mitochondrial DNA data, morphometric analyses, and male genital morphology to investigate Hydrochara populations in continental Croatia. Specimens were collected from floodplain and lowland aquatic habitats across major river basins, morphologically identified and verified using cytochrome oxidase subunit I (16S) sequences through comparison with reference data from public databases (GenBank and BOLD). Molecular analyses confirmed the presence of H. caraboides and Hydrochara flavipes in continental Croatia. A single specimen from the upper Drava River basin (CROH030-26) formed a distinct mitochondrial lineage positioned between H. caraboides and Hydrochara dichroma in the COI phylogeny. Morphometric analyses showed extensive overlap between this specimen and H. caraboides, indicating no clear differentiation in external body size. In contrast, examination of male genitalia revealed an intermediate aedeagus morphology with transitional characters between H. caraboides and H. dichroma. Haplotype network analysis revealed a star-like structure with a dominant central haplotype shared by most H. caraboides specimens and several low-frequency variants, while the divergent specimen occupies a peripheral position, separated from the main cluster by multiple mutational steps. These results indicate that H. caraboides is a genetically heterogeneous taxon comprising multiple divergent mitochondrial lineages, suggesting that lineage diversity within this species may be underestimated. By integrating molecular and morphological evidence, this study provides new insights into the lineage diversity of Hydrochara in floodplain ecosystems of south-eastern Europe and highlights the importance of integrative approaches for resolving species boundaries and informing freshwater biodiversity conservation. Full article

Oral squamous cell carcinoma (OSCC) typically develops in individuals with established risk factors such as tobacco and alcohol use, yet an increasing number of cases occur in young non-smoking, non-drinking (NSND) patients. We report a case of oral tongue OSCC in a 33-year-old woman who is a never-smoker and never-drinker without identifiable environmental or local risk factors. The patient underwent surgical treatment followed by adjuvant radiotherapy and remains disease-free 15 months after therapy. Whole-exome sequencing (WES) revealed a pathogenic truncating TP53 mutation together with additional somatic alterations affecting genes involved in DNA repair, hypoxia adaptation, mitochondrial function, and epigenetic regulation. The heterogeneous mutational profile suggests branched tumor evolution and the involvement of non-classical tumorigenic pathways. This report contributes to the growing evidence that OSCC in young NSND patients represents a biologically distinct subgroup and demonstrates the value of comprehensive genomic profiling for improving understanding of tumor heterogeneity and potential molecular drivers in the absence of traditional carcinogenic exposures. Full article

Background: Translocation morphology renal cell carcinoma (tRCC) accounts for nearly half of all pediatric RCC cases. Biological study AREN14B4-Q aimed to characterize the molecular landscape of tRCC using samples acquired from patients enrolled in the Children’s Oncology Group Risk Classification and Biobanking study AREN03B2. Methods: From 2006 to 2014, patients <30 yr old with renal tumors were prospectively enrolled in AREN03B2, a Central IRB-approved biobanking study. All pediatric RCC cases underwent a detailed central pathology review and molecular diagnostics to accurately classify RCC subtypes. Samples with confirmed tRCC and appropriate informed consent were identified with adequate tissue for RNA and DNA extraction, along with germline DNA, for whole-genome sequencing (WGS), RNA sequencing, and DNA methylation analyses. Results: From 41 patients, high-quality samples allowed for 18 tumors and non-tumor DNA to be analyzed via WGS, 19 via DNA methylation, and 36 RNA samples via transcriptome sequencing. Consistent with and extending clinical cytogenetic findings, WGS and fusion transcript analyses confirmed very few additional mutations beyond the tRCC translocation. No recurrent genomic copy number gains/losses were found. RNA and WGS analyses enabled sub-classification of tRCC, closely aligning with the different TFE3 fusion partners. DNA methylation analyses demonstrated less tRCC sub-stratification compared with RNA analyses. Pathways activated in tRCC were involved in epithelial differentiation, extracellular matrix organization, apoptosis, immune regulation, signal transduction, and angiogenesis. Conclusions: Arrested epithelial differentiation is the overarching driver in tRCC and is strongly correlated with the specific subclasses of fusion transcript generated by the genetic translocation TFE fusion partner. Negative regulation of apoptosis, increased M2 macrophage expression, and enhanced angiogenesis also appear to be functional features of tRCCs, as are increased expression of matrix metalloproteinases, PI3K-AKT/mTOR/MAPK signaling, and mitochondrial metabolism, highlighting potential therapeutic options beyond direct targeting of the oncogenic driver fusions. Full article

Introduction: Parkinson’s disease (PD) is a prevalent neurodegenerative disorder, with several proposed pathogenic mechanisms. Given the established role of mitochondrial dysfunction in PD, this study seeks to investigate the enrichment of rare genetic variants tied to mitochondrial metabolism in cases of early-onset and familial PD. Methods: We performed a retrospective analysis on 248 early-onset and familial PD patients and 1622 control individuals. We assessed both pathway-level and gene-level burden of germline rare variants detected using exome sequencing in 467 nuclear genes related to mitochondrial metabolism. Results: Gene-set mutation burden analysis indicated an increased burden in genes associated with mtDNA maintenance. In addition, gene-level analysis identified a possible association between PD and rare variant burden in 14 mitochondrial metabolism-related genes under dominant or recessive inheritance models. Conclusions: Our findings support a potential contribution of rare germline variants affecting mitochondrial metabolism to the susceptibility in early-onset and familial PD. Full article

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial lung disease characterized by irreversible fibrosis. Aberrant cell differentiation plays a crucial role in the development of IPF. Although recent studies have suggested that mitochondrial dysfunction may play a role in IPF, its direct impact on fibrosis remains unclear. This study aimed to clarify the role of mitochondria in lung cell differentiation and pulmonary fibrosis development by employing mito-mice ND6^M, in which the activity of respiratory chain complex I is decreased due to a mitochondrial DNA mutation (G13997A). Pulmonary fibrosis was induced by administering bleomycin (BLM) to both wild-type and mito-mice ND6^M. Bone marrow-derived macrophages and primary lung fibroblasts, generated from both types of mice, were analyzed to evaluate M1/M2 polarization and myofibroblast differentiation, respectively. Compared to wild-type mice, mito-mice ND6^M exhibited more severe fibrosis and lower survival rates following BLM inoculation. Lactate production in the lungs after BLM administration was significantly higher in mito-mice ND6^M than in wild-type mice. TGF-β1-treated fibroblasts from mito-mice ND6^M exhibited increased α-smooth muscle actin expression. While type I collagen expression was not different between these mice, TGF-β1-induced expression of phosphoserine phosphatase and serine hydroxymethyltransferase2, two of the enzymes involved in the serine–glycine pathway, was significantly higher in mito-mice ND6^M than in wild-type mice. On the other hand, mitochondrial dysfunction had a small effect on pulmonary inflammation and on M1/M2 macrophage polarization. In conclusion, mitochondrial dysfunction promotes TGF-β1-induced myofibroblast differentiation and BLM-induced pulmonary fibrosis. Mitochondria-dependent metabolic reprogramming may therefore represent a promising therapeutic target in IPF. Full article

Mitochondria play a fundamental role in human reproduction by supplying the energy required for key early reproductive processes. As mitochondrial Deoxyribonucleic acid (mtDNA) is maternally inherited, pathogenic mutations can lead to multisystem disorders that are transmitted to offspring. Mitochondrial replacement therapy (MRT) has emerged as a promising assisted reproductive approach to prevent the transmission of pathogenic mtDNA by replacing defective mitochondria with healthy donor mitochondria. There have been recent reports of successful MRT in humans. However, MRT remains a relatively new procedure and needs further experiments to establish its long-term safety and effectiveness. Overall, mitochondrial replacement therapy holds significant promise in helping families build healthier futures. This review explores the evolution of mitochondrial DNA modification in reproductive cells and addresses the associated ethical considerations, including acceptable clinical indications, reproductive choices, and long-term considerations for affected children. Full article

Background: Chromophobe renal cell carcinoma (ChRCC) is characterized by the accumulation of abnormal mitochondria, a high rate of mitochondrial DNA (mtDNA) mutations, and altered oxidative metabolism. There are no existing circulating biomarkers to distinguish metastatic ChRCC from clear cell renal cell carcinoma (ccRCC). Methods: High-throughput plasma proteomic profiling using the SomaScan platform was performed in 18 ChRCC (including 16 metastatic ChRCC) and 197 metastatic ccRCC patients. Data were harmonized to generate a unified 7K-protein matrix. Results: Differential expression analysis was performed using limma (version 3.62.2). Of 7272 quantified human plasma proteins, 209 were differentially expressed between ChRCC and ccRCC. Upregulated proteins in ChRCC included essential β-oxidation enzymes such as ECH1 (enoyl-CoA hydratase 1) and ECI1 (enoyl-CoA delta-isomerase 1), suggesting increased long-chain fatty acid degradation. Creatine and energy-buffering pathways were also represented, with increased CKMT1A (Creatine Kinase, Mitochondrial 1A) in ChRCC. KIM-1 (Kidney Injury Molecule-1) and leptin were lower in ChRCC, consistent with the known upregulation of these proteins in ccRCC. Pathway enrichment analyses revealed an overrepresentation of mitochondrial protein degradation, fatty acid β-oxidation, and respiratory electron transport in ChRCC, suggesting that ChRCC sheds a unique mitochondrial signature into the peripheral circulation. A bootstrap-based LASSO logistic regression restricted to upregulated mitochondrial proteins in ChRCC vs. ccRCC consistently selected ECI1 and CKMT1A. The LASSO model achieved an AUROC of 0.964. Conclusions: Compared to ccRCC, the plasma proteome of metastatic ChRCC is dominated by mitochondrial metabolic enzymes, revealing a systemic metabolic phenotype strikingly aligned with the known histologic accumulation of abnormal mitochondria in ChRCC cells. Full article

Pancreatic cancer (PC) is a highly aggressive malignancy characterized by limited opportunities for early diagnosis and poor clinical outcomes, underscoring the need for minimally invasive biomarkers to improve detection and patient stratification. Given emerging evidence that mitochondrial DNA (mtDNA) alterations reflect cancer-related biological processes, this study investigated whether blood-derived mtDNA profiles could provide clinically relevant information in PC. In this exploratory study, whole-blood mtDNA from 33 PC patients and 10 healthy individuals were analyzed using next-generation sequencing to assess single-nucleotide variants (SNVs), allele frequencies, and mtDNA copy number. A total of 252 unique mtDNA SNVs were identified, including variants exclusive to PC patients, variants unique to controls, and variants shared between groups. While the overall SNV burden did not differ significantly between groups, PC patients showed distinct mutation distributions and allele frequency patterns, with cancer-exclusive variants occurring predominantly at low allele frequencies. Mutation hotspots were observed in the ND5, COI, and D-loop regions, implicating genes involved in oxidative phosphorylation and mtDNA maintenance. Although mtDNA copy number did not differ significantly between groups, greater variability was observed among PC patients and was associated with differences in survival outcomes. Overall, these findings indicate that blood-based mtDNA profiling captures biologically relevant variation associated with PC and supports further development of integrated mtDNA-based approaches for improved risk assessment and patient stratification. Full article

Bile acids are widely distributed in the human gastrointestinal tract. A literature review indicates that bile acids may have a role in initiating cancers in every organ of the digestive system. The estimated number of new digestive system cancers world-wide in 2022 was about 5 million. In the particular case of colon cancer, secondary bile acids produced in response to a high fat diet disrupt colonic epithelial cell mitochondrial membranes. This disruption leads to the release of oxidative free radicals that damage DNA, potentially leading to carcinogenic mutations. High levels of colonic bile acids may also alter the gut microbiome, with some bacteria causing inflammation and increased reactive oxygen species leading to DNA damage. Also, bile acids taken up by receptors on the surface of gastrointestinal tract cells can activate NF-kB. In turn, NF-kB may activate a super-enhancer at an oncogene. Bile acid reflux also plays a significant role in esophageal adenocarcinoma, stomach cancer and small intestine carcinogenesis. In addition, cancers of the pancreas, liver, and biliary tract can be caused by the constriction of the common bile duct leading to reflux of bile acids back into these organs. Gastroesophageal reflux involving bile acids may also contribute to hypopharyngeal squamous cell carcinogenesis. Thus, bile acids are a likely major contributory cause of cancer throughout the digestive tract. Full article