Alternative oxidase (AOX) (EC 1.10.3.11) is a terminal oxidase in the mitochondrial inner membrane that branches the canonical electron transport system (ETS). AOX is ubiquitous in plants, frequently found in fungi and protists and presents a more sporadic distribution in metazoans. More recently, AOX has gained attention due to its potential application in gene therapy for treatment of mitochondrial diseases. Here we characterized the AOX in the basal Dipteran, Pseudolycoriella hygida using a combination of genomic analyses, molecular, functional and in vivo survival assays. AOX is a single copy gene that encodes three developmental stage specific protein isoforms. AOX localizes to the mitochondria in adult thoracic muscles, which present cyanide-resistant respiration that is sensitive to the AOX inhibitor salicylhydroxamic acid (SHAM). Both the cyanide-resistant respiration and AOX levels gradually increase during aging, but are not influenced by thermal stress. Thoracic mitochondria respire using substrates derived from several metabolic routes, such as pyruvate, proline, acylcarnitine, NADH and glycerol-3P, and present values of oxidative phosphorylation capacity ((P-L)/E = 0.70) and coupling (P/L = 4.35; L/E = 0.21). Adult flies exhibit a high survival resistance for SHAM-sensitive complex III inhibition. Together, our results demonstrate the presence of a functional AOX in a terrestrial arthropod and provide insights regarding AOX function in animals and evolution of respiratory systems in metazoans. Psl. hygida emerges as a natural and valuable model for comprehensive AOX research at the whole-organism level which complements models expressing the heterologous enzyme.

Human mitochondrial DNA (mtDNA) harbors essential mutations linked to aging, neurodegenerative diseases, and complex muscle disorders. Due to its uniparental and haploid inheritance, mtDNA captures matrilineal evolutionary trajectories, playing a crucial role in population and medical genetics. However, critical questions about the genomic diversity patterns, inheritance models, and evolutionary and medical functions of mtDNA remain unresolved or underexplored, particularly in the transition from traditional genotyping to large-scale genomic analyses. This review summarizes recent advancements in data-driven genomic research and technological innovations that address these questions and clarify the biological impact of nuclear-mitochondrial segments (NUMTs) and mtDNA variants on human health, disease, and evolution. We propose a streamlined pipeline to comprehensively identify mtDNA and NUMT genomic diversity using advanced sequencing and computational technologies. Haplotype-resolved mtDNA sequencing and assembly can distinguish authentic mtDNA variants from NUMTs, reduce diagnostic inaccuracies, and provide clearer insights into heteroplasmy patterns and the authenticity of paternal inheritance. This review emphasizes the need for integrative multi-omics approaches and emerging long-read sequencing technologies to gain new insights into mutation mechanisms, the influence of heteroplasmy and paternal inheritance on mtDNA diversity and disease susceptibility, and the detailed functions of NUMTs.

Mitochondria, essential organelles responsible for cellular energy production, emerge as a key factor in the pathogenesis of neurodegenerative disorders. This review explores advancements in mitochondrial biology studies that highlight the pivotal connection between mitochondrial dysfunctions and neurological conditions such as Alzheimer's, Parkinson's, Huntington's, ischemic stroke, and vascular dementia. Mitochondrial DNA mutations, impaired dynamics, and disruptions in the ETC contribute to compromised energy production and heightened oxidative stress. These factors, in turn, lead to neuronal damage and cell death. Recent research has unveiled potential therapeutic strategies targeting mitochondrial dysfunction, including mitochondria targeted therapies and antioxidants. Furthermore, the identification of reliable biomarkers for assessing mitochondrial dysfunction opens new avenues for early diagnosis and monitoring of disease progression. By delving into these advancements, this review underscores the significance of understanding mitochondrial biology in unraveling the mechanisms underlying neurodegenerative disorders. It lays the groundwork for developing targeted treatments to combat these devastating neurological conditions.

Mitochondria are traditionally viewed as the powerhouses of eukaryotic cells, i.e., the main providers of the metabolic energy required to maintain their viability and function. However, the role of these ubiquitous intracellular organelles far extends energy generation, encompassing a large suite of functions, which they can adjust to changing physiological conditions. These functions rely on a sophisticated membrane system and complex molecular machineries, most of which imported from the cytosol through intricate transport systems. In turn, mitochondrial plasticity is rooted on mitochondrial biogenesis, mitophagy, fusion, fission, and movement. Dealing with all these aspects and terminology can be daunting for newcomers to the field of mitochondria, even for those with a background in biological sciences. The aim of the present educational article, which is part of a special issue entitled "Mitochondria in aging, cancer and cell death", is to present these organelles in a simple and concise way. Complex molecular mechanisms are deliberately omitted, as their inclusion would defeat the stated purpose of the article. Also, considering the wide scope of the article, coverage of each topic is necessarily limited, with the reader directed to excellent reviews, in which the different topics are discussed in greater depth than is possible here. In addition, the multiple cell type-specific genotypic and phenotypic differences between mitochondria are largely ignored, focusing instead on the characteristics shared by most of them, with an emphasis on mitochondria from higher eukaryotes. Also ignored are highly degenerate mitochondrion-related organelles, found in various anaerobic microbial eukaryotes lacking canonical mitochondria.

This study aims to evaluate visual function and morphological changes in patients with adrenoleukodystrophy (ALD) through sweep-source optical coherence tomography (SS-OCT) and patterned visual evoked potentials (PVEP), with the goal of providing more accurate and comprehensive data for the diagnosis, monitoring, and assessment of treatment efficacy in patients with ALD.

This study included 46 ALD patients and 44 healthy controls. The thickness of the retinal nerve fiber layer (RNFL) around the optic disc, as well as the macular RNFL and ganglion cell-inner plexiform layer (GCIPL) thickness, was assessed using SS-OCT. The peak time and amplitude of the P100 wave were also measured using PVEP. Factors that were statistically significant in the univariate analysis were subjected to stepwise binary logistic regression analysis for further investigation. Predictive performance was evaluated by constructing receiver operating characteristic (ROC) curves and compared using DeLong's test.

Compared with the control patients, ALD patients presented a significant increase in the peak time of the P100 wave (P < 0.05); however, no notable difference in amplitude was observed (P > 0.05). Additionally, substantial decreases in the RNFL and GCIPL thicknesses were observed within the parafoveal ring, especially in the superior and nasal quadrants (P < 0.05). The area under the curve for the binary logistic stepwise regression model was 0.883, with a sensitivity of 0.95, which surpassed the performance of the individual parameters.

ALD patients present with abnormal retinal structures and a PVEP peak time delay. Combining these two parameters could increase the accuracy of an early ALD diagnosis.

Cardiovascular complications are a hallmark of Post-Acute Sequelae of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection (PASC), yet the mechanisms driving persistent cardiac dysfunction remain poorly understood. Emerging evidence implicates mitochondrial dysfunction in immune cells as a key contributor. This study investigated whether CD14++ monocytes from long COVID patients exhibit bioenergetic impairment, mitochondrial DNA (mtDNA) damage, and defective oxidative stress adaptation, which may underlie cardiovascular symptoms in PASC. CD14++ monocytes were isolated from 14 long COVID patients with cardiovascular symptoms (e.g., dyspnea, angina) and 10 age-matched controls with similar cardiovascular risk profiles. Mitochondrial function was assessed using a Seahorse Agilent Analyzer under basal conditions and after oxidative stress induction with buthionine sulfoximine (BSO). Mitochondrial membrane potential was measured via Tetramethylrhodamine Ethyl Ester (TMRE) assay, mtDNA integrity via qPCR, and reactive oxygen species (ROS) dynamics via Fluorescence-Activated Cell Sorting (FACS). Parallel experiments exposed healthy monocytes to SARS-CoV-2 spike protein to evaluate direct viral effects. CD14++ monocytes from long COVID patients with cardiovascular symptoms (n = 14) exhibited profound mitochondrial dysfunction compared to age-matched controls (n = 10). Under oxidative stress induced by buthionine sulfoximine (BSO), long COVID monocytes failed to upregulate basal respiration (9.5 vs. 30.4 pmol/min in controls, p = 0.0043), showed a 65% reduction in maximal respiration (p = 0.4035, ns) and demonstrated a 70% loss of spare respiratory capacity (p = 0.4143, ns) with significantly impaired adaptation to BSO challenge (long COVID + BSO: 9.9 vs. control + BSO: 54 pmol/min, p = 0.0091). Proton leak, a protective mechanism against ROS overproduction, was blunted in long COVID monocytes (3-fold vs. 13-fold elevation in controls, p = 0.0294). Paradoxically, long COVID monocytes showed reduced ROS accumulation after BSO treatment (6% decrease vs. 1.2-fold increase in controls, p = 0.0015) and elevated mitochondrial membrane potential (157 vs. 113.7 TMRE fluorescence, p = 0.0179), which remained stable under oxidative stress. mtDNA analysis revealed severe depletion (80% reduction, p < 0.001) and region-specific damage, with 75% and 70% reductions in amplification efficiency for regions C and D (p < 0.05), respectively. In contrast, exposure of healthy monocytes to SARS-CoV-2 spike protein did not recapitulate these defects, with preserved basal respiration, ATP production, and spare respiratory capacity, though coupling efficiency under oxidative stress was reduced (p < 0.05). These findings suggest that mitochondrial dysfunction in long COVID syndrome arises from maladaptive host responses rather than direct viral toxicity, characterized by bioenergetic failure, impaired stress adaptation, and mitochondrial genomic instability. This study identifies persistent mitochondrial dysfunction in long COVID monocytes as a critical driver of cardiovascular complications in PASC. Key defects-bioenergetic failure, impaired stress adaptation and mtDNA damage-correlate with clinical symptoms like heart failure and exercise intolerance. The stable elevation of mitochondrial membrane potential and resistance to ROS induction suggest maladaptive remodeling of mitochondrial physiology. These findings position mitochondrial resilience as a therapeutic target, with potential strategies including antioxidants, mtDNA repair agents or metabolic modulators. The dissociation between spike protein exposure and mitochondrial dysfunction highlights the need to explore host-directed mechanisms in PASC pathophysiology. This work advances our understanding of long COVID cardiovascular sequelae and provides a foundation for biomarker development and targeted interventions to mitigate long-term morbidity.

mtDNA mutator mice (Polgmut/mut mice) have reinforced the mitochondrial theory of aging. These mice accumulate multiple mutations in mtDNA with age due to a homozygous proofreading-deficient mutation in mtDNA polymerase gamma (Polg), resulting in mitochondrial respiratory dysfunction and premature aging phenotypes. However, whether the accumulation of multiple mutations in Polgmut/mut mice induces mitochondrial respiratory dysfunction remains unclear. Here, we determined the accurate mtDNA genotype, including the frequency of total mutations and the number of non-synonymous substitutions and pathogenic mutations, using next-generation sequencing in the progeny of all three genotypes obtained from the mating of heterozygous mtDNA mutator mice (Polg+/mut mice) and examined their correlation with mitochondrial respiratory activity. Although Polg+/mut mice showed equivalent mtDNA genotype to Polg+/+ (wild-type) mice, the mitochondrial respiratory activity in the Polg+/mut mice was mildly reduced. To further investigate the causal relationship between mtDNA genotype and mitochondrial respiratory activity, we experimentally varied the mtDNA genotype in Polg mice. However, mitochondrial respiratory activity was mildly reduced in Polg+/mut mice and severely reduced in Polgmut/mut mice, regardless of the mtDNA genotype. Moreover, by varying the mtDNA genotype, some Polg+/+ mice showed mtDNA genotype equivalent to those of Polgmut/mut mice, but mitochondrial respiratory activity in Polg+/+ mice was normal. These results indicate that the mitochondrial respiratory dysfunction observed in mice with proofreading-deficient mutation in Polg is correlated with the nuclear genotype of Polg rather than the mtDNA genotype. Thus, the mitochondrial theory of aging in Polgmut/mut mice needs further re-examination.

Hypoxia can lead to severe consequences for brain function, particularly in regions with high metabolic demands such as the hippocampus. Excessive production of reactive oxygen species (ROS) during hypoxia can initiate a cascade of oxidative stress, evoking cellular damage and neuronal dysfunction. Most of the studies characterizing the formation of ROS are performed in the context of ischemia induced by oxygen-glucose deprivation, thus, the role of hypoxia in less severe conditions requires further clarification. The aim of this work was to identify the major mechanisms of ROS generation and assess flavoprotein autofluorescence changes. For ROS detection, the slices were incubated with the indicator H2DCFDA, while intrinsic FAD-linked autofluorescence was recorded from indicator free slices. All signals were measured under hypoxia, at the hippocampal mossy fiber synapses of CA3 area, which were chemically stimulated using 20 mM KCl. The results suggest that ROS is formed in the mitochondria, during moderate hypoxia. The blockage of mitochondrial complexes I, III and IV with rotenone, myxothiazol and sodium azide, respectively, and of the mitochondrial calcium uniporter with Ru265, led to the abolishment of ROS changes and to an increase of FAD-linked autofluorescence (with the exception of the complexes III and IV). The blockage of the enzyme oxidases NADPH and xanthine oxidase also impaired ROS formation and rose FAD-linked autofluorescence. Thus, the blockage of any of the steps of the process of ROS formation, namely the activation of critical MRC complexes, calcium entry into the mitochondria, or enzyme oxidases activity, ceases the production of ROS.

A/J mice exhibited a severe hearing loss (HL) at juvenile stage. Up-to-date, studies on HL in A/J mice have mostly focused on the damage or dysfunction of hair cells (HCs), spiral ganglion neurons (SGNs), and stereocilia. We examined A/J mice at the early postnatal stage and found that the damage and the loss of outer hair cells (OHCs) are not severe enough to explain the profound HL observed at this age, which suggests that other cochlear defects may be responsible for HL. To better understand the mechanisms of early-onset HLin A/J mice, we characterized the pathology of the cochlea from postnatal day 3 to day 21.

Our results showed defects in cochlear HC stereocilia and MET channel function as early as 3 days old. We also found abnormal localization and a significant reduction in the number of ribbon synapses in 2-week-old A/J mice. There are also abnormalities in the cochlear nerve innervation and terminal swellings in 3-week-old A/J mice.

All of the abnormalities of cochlear existed in the A/J mice were identified in the juvenile stage and occurred before HCs or auditory nerve loss and was the initial pathological change. Our results suggest that developmental defects and subsequent cochlear degeneration are responsible for early-onset hearing loss in A/J mice.

Mitochondrial dysfunction is a hallmark of idiopathic neurodegenerative diseases, including Parkinson disease, amyotrophic lateral sclerosis, Alzheimer disease and Huntington disease. Familial forms of Parkinson disease and amyotrophic lateral sclerosis are often characterized by mutations in genes associated with mitophagy deficits. Therefore, enhancing the mitophagy pathway may represent a novel therapeutic approach to targeting an underlying pathogenic cause of neurodegenerative diseases, with the potential to deliver neuroprotection and disease modification, which is an important unmet need. Accumulating genetic, molecular and preclinical model-based evidence now supports targeting mitophagy in neurodegenerative diseases. Despite clinical development challenges, small-molecule-based approaches for selective mitophagy enhancement - namely, USP30 inhibitors and PINK1 activators - are entering phase I clinical trials for the first time.

Mitochondrial diseases are historically difficult to study. They cause multi-systemic defects with prevalent impairment of hard-to-access tissues such as the brain and the heart. Furthermore, they suffer from a paucity of conventional model systems, especially because of the challenges associated with mitochondrial DNA (mtDNA) engineering. Consequently, most mitochondrial diseases are currently untreatable. Human induced pluripotent stem cells (iPSCs) represent a promising approach for developing human model systems and assessing therapeutic avenues in a patient- and tissue-specific context. iPSCs are being increasingly used to investigate mitochondrial diseases, either for dissecting mutation-specific defects within two-dimensional (2D) or three-dimensional (3D) progenies or for unveiling the impact of potential treatment options. Here, we review how iPSC-derived 2D cells and 3D organoid models have been applied to the study of mitochondrial diseases caused by either nuclear or mtDNA defects. We anticipate that the field of iPSC-driven modeling of mitochondrial diseases will continue to grow, likely leading to the development of innovative platforms for treatment discovery and toxicity that could benefit the patient community suffering from these debilitating disorders with highly unmet medical needs.

Pneumonia is a ubiquitous disease caused by viral and bacterial infections, characterized by high levels of reactive oxygen species in inflamed areas. Therapeutic strategies targeting reactive oxygen species levels in pneumonia have limited success due to the intricate nature of lung tissues and lung inflammatory responses. Here we describe an inhalable, non-invasive therapeutic platform composed of engineered cerium-based tannic acid nanozymes bound to a self-assembling peptide. In vitro and in vivo studies show that the nanozyme is internalized mostly by activated macrophages and epithelial cells in the inflamed sites. In the oxidative environments of a mouse model of viral pneumonia, nanozyme aggregates into catalytically active structures that reduce reactive oxygen species levels and inflammatory cytokine production and promote macrophage polarization to the prohealing (M2) phenotype. Moreover, the nanozyme attenuates bacterial inflammation and reduces tissue damage in a mouse viral pneumonia model with secondary bacterial infection. Overall, this nanozyme platform is a promising strategy for treating pneumonia and its associated conditions.

Gene editing technology involves modifying target genes to alter genetic traits and generate new phenotypes. Beginning with zinc-finger nucleases (ZFN) and transcription activator-like effector nucleases (TALEN), the field has evolved through the advent of clustered regularly interspaced short palindromic repeats and CRISPR-associated protein (CRISPR-Cas) systems, and more recently to base editors (BE) and prime editors (PE). These innovations have provided deep insights into the molecular mechanisms of complex biological processes and have paved the way for novel therapeutic strategies for a range of diseases. Gene editing is now being applied in the treatment of both genetic and acquired kidney diseases, as well as in kidney transplantation and the correction of genetic mutations. This review explores the current applications of mainstream gene editing technologies in biology, with a particular emphasis on their roles in kidney disease research and treatment of. It also addresses the limitations and challenges associated with these technologies, while offering perspectives on their future potential in this field.

Recent studies have reported that endurance exercise enhances mitochondrial function, facilitating discussions of its potential as a therapeutic strategy for mitochondrial diseases caused by the accumulation of mutant mitochondrial DNA (mtDNA). In this study, we assessed the effects of endurance exercise on muscle pathology in a mitochondrial disease mouse model (mito-miceΔ) that is characterized by severe clinical phenotypes owing to the predominant accumulation of mtDNA with a large-scale deletion (ΔmtDNA). Contrary to expectations that endurance exercise may enhance mitochondrial function, endurance exercise exacerbated muscle pathology in mito-miceΔ. Therefore, exercise interventions should be potentially avoided in patients with severe mitochondrial diseases.

Ovarian aging has become a focal point in current research on female aging and refers to the gradual decline in ovarian function as women age. Numerous factors influence ovarian aging, among which mitochondrial function is one because it plays a crucial role by affecting oocytes and granulosa cells. Mitochondrial deterioration not only leads to a decrease in oocyte quality but also hinders follicle development, further impacting women's reproductive health and fertility.

This review summarizes and integrates research on the impact of mitochondrial function on ovarian aging, outlining the mechanisms by which mitochondria regulate the functions of oocytes and granulosa cells. This study aims to provide potential therapeutic directions to mitigate mitochondrial decline and support female reproductive health.

According to a 2023 study published in Cell, factors such as oxidative stress, mitochondrial dysfunction, chronic inflammation, and telomere shortening collectively drive ovarian aging, directly affecting female fertility. Among these factors, mitochondrial dysfunction plays a key role. This study reviewed literature from databases such as PubMed, Google Scholar, and CNKI, using keywords such as "mitochondrial dysfunction", "decline in oocyte quality and quantity", and "ovarian aging", aiming to summarize current research on the mechanisms of the impact of mitochondrial dysfunction on ovarian aging and provide theoretical support for future exploration of related therapeutic strategies.

The main characteristics of ovarian aging include a decline in oocyte quantity and quality, fluctuations in hormone levels, and a reduction in granulosa cell function. Studies have shown that mitochondria affect fertility by regulating cellular energy metabolism, exacerbating oxidative stress, causing mitochondrial DNA (mtDNA) damage, and impacting the physiological function of granulosa cells within the ovary, gradually diminishing the ovarian reserve.

This review focuses on analyzing the effects of mitochondrial decline on energy production in oocytes and granulosa cells, the accumulation of reactive oxygen species (ROS), and the calcium ion (Ca2+) concentration, which all contribute to the ovarian aging process, and understanding them will provide new insights into the mechanisms of ovarian aging.

Therapeutic interventions targeting mitochondrial dysfunction may help delay ovarian aging and improve female reproductive health.

The brain is an organ that consumes a substantial amount of oxygen, and a reduction in oxygen concentration can rapidly lead to significant and irreversible brain injury. The progression of brain injury during hypoxia involves the depletion of intracellular adenosine triphosphate (ATP) due to decreased oxidative phosphorylation in the inner mitochondrial membrane. Allopurinol is a purine analog inhibitor of xanthine oxidoreductase that protects against hypoxic/ischemic brain injury; however, its underlying mechanism of action remains unclear. In addition, febuxostat is a non-purine xanthine oxidoreductase inhibitor with a different inhibitory mechanism from allopurinol. The impact of febuxostat on brain injury has not been well investigated. Therefore, this study aimed to examine brain ATP and its catabolite levels in the presence or absence of allopurinol and febuxostat under hypoxic conditions by inactivating brain metabolism using focal microwave irradiation. The hypoxic treatment caused a decrease in the adenylate energy charge and ATP levels and an increase in its catabolic products in mouse brains. The febuxostat group showed higher energy charge and ATP levels and lower ATP catabolites than the control group. Notably, despite the comparable suppression of uric acid production in both inhibitor groups, allopurinol treatment was less effective than febuxostat. These results suggest that febuxostat effectively prevents hypoxia-induced ATP degradation in the brain and that its effect is more potent than allopurinol. This study will contribute to developing therapies for improving hypoxia-induced brain dysfunction.

Given the uniqueness of the mitochondria, and the fact that they have their own genome, mitochondrial-derived microproteins (MDPs) are similar to, but different from, nuclear-encoded microproteins. The discovery of an increasing number of microproteins from this organelle and the importance of mitochondria to cellular and organismal health make it a priority to study this novel class of proteins in search of possible therapeutic targets and cures. In this review, we discuss the history of MDP discovery, describe the function of each MDP, and conclude with future goals and techniques to help discover more MDPs.

Organelles are specialized subunits within cells which carry out vital functions crucial to cellular survival and form a tightly regulated network. Dysfunctions in any of these organelles are linked to numerous diseases impacting virtually every organ system in the human body. Targeted delivery of therapeutics to specific organelles within the cell holds great promise for overcoming challenging diseases and improving treatment outcomes through the minimization of therapeutic dosage and off-target effects. Nanoparticles are versatile and effective tools for therapeutic delivery to specific organelles. Nanoparticles offer several advantageous characteristics, including a high surface area-to-volume ratio for efficient therapeutic loading and the ability to attach targeting moieties (tethers) that enhance delivery. The choice of nanoparticle shape, size, composition, surface properties, and targeting ligands depends on the desired target organelle and therapeutic effect. Various nanoparticle platforms have been explored for organelle targeting, such as liposomes, polymeric nanoparticles, dendrimers, and inorganic nanoparticles. In this review, current and emerging approaches to nanoparticle design are examined in the context of various diseases linked to organelle dysfunction. Specifically, advances in nanoparticle therapies targeting organelles such as the nucleus, mitochondria, lysosomes/endosomes, Golgi apparatus, and endoplasmic reticulum are comprehensively and critically discussed.

Polycystic ovary syndrome (PCOS) is a common endocrine disorder affecting women of reproductive age characterized by a spectrum of clinical, metabolic, reproductive, and psychological abnormalities. This syndrome is associated with significant long-term health risks, necessitating elucidation of its pathophysiology, early diagnosis, and comprehensive management strategies. Several contributory factors in PCOS, including androgen excess and insulin resistance, collectively enhance oxidative stress, which subsequently leads to mitochondrial dysfunction. However, the precise mechanisms through which oxidative stress induces mitochondrial dysfunction remain incompletely understood. Comprehensive searches of electronic databases were conducted to identify relevant studies published up to 30 September 2024. Mitochondria, the primary sites of reactive oxygen species (ROS) generation, play critical roles in energy metabolism and cellular homeostasis. Oxidative stress can inflict damage on components, including lipids, proteins, and DNA. Damage to mitochondrial DNA (mtDNA), which lacks efficient repair mechanisms, may result in mutations that impair mitochondrial function. Dysfunctional mitochondrial activity further amplifies ROS production, thereby perpetuating oxidative stress. These disruptions are implicated in the complications associated with the syndrome. Advances in genetic analysis technologies, including next-generation sequencing, have identified point mutations and deletions in mtDNA, drawing significant attention to their association with oxidative stress. Emerging data from mtDNA mutation analyses challenge conventional paradigms and provide new insights into the role of oxidative stress in mitochondrial dysfunction. We are rethinking the pathogenesis of PCOS based on these database analyses. In conclusion, this review explores the intricate relationship between oxidative stress, mtDNA mutations, and mitochondrial dysfunction, offers an updated perspective on the pathophysiology of PCOS, and outlines directions for future research.

Background/Objectives: Mitochondrial dysfunction is increasingly recognized as a central contributor to neurodegenerative diseases and age-related cognitive decline. Individuals with Down syndrome (DS) are at high risk of neurodegeneration due to Alzheimer's disease (AD). This study aims to explore the relationship between mitochondrial dysfunction, brain amyloid-beta (Aβ) deposition, and cognitive decline in this population. Methods: We investigated mitochondrial function, brain amyloid-beta burden, and cognitive performance in a pilot study of a cohort of 10 eligible adults with DS selected from a sample of 28 individuals with DS. Phosphorus-31 magnetic resonance spectroscopy (31P-MRS) was used to assess mitochondrial function in skeletal muscle using a post-exercise paradigm, while positron emission tomography using 11C-Pittsburgh compound B (PiB-PET) measured brain Aβ deposition. Cognitive performance was evaluated using the Cambridge Cognitive Examination adapted for individuals with Down syndrome (CAMCOG-DS) and executive function batteries. Results: Significant correlations were observed between slowed phosphocreatine (PCr) recovery in muscle and increased Aβ deposition in key brain regions, particularly the striatum. Cognitive performance inversely correlated with mitochondrial function, with pronounced deficits in memory and executive function tasks. Notably, an individual carrying the APOE-ε4 allele exhibited the poorest mitochondrial function, highest Aβ burden, and most severe cognitive impairment, suggesting a potential interaction between genetic risk and mitochondrial health. Conclusions: These findings highlight the role of mitochondrial dysfunction in DS-associated AD (DSAD) and its impact on cognition in adults. The results support targeting mitochondrial pathways as a potential therapeutic strategy to mitigate AD progression in DS populations. Further research with larger cohorts and longitudinal designs is needed to clarify causative mechanisms and develop effective interventions.

This study aims to investigate the impact of subclinical hypothyroidism (SCH) during pregnancy on mitochondrial DNA (mtDNA) methylation in the brain tissues of rat offspring.

Sixteen SD rats were randomly divided into two groups: control group (CON) and SCH group. BS-seq sequencing was used to analyze mtDNA methylation levels in the offspring's brain tissues; the 2,7-dichlorofluorescin diacetate (DCFH-DA) probe method was employed to detect reactive oxygen species (ROS) levels in brain tissues; electron microscopy was utilized to observe the mitochondrial structure in the hippocampal tissues of the offspring.

In the analysis of differentially methylated regions (DMRs), the mitochondrial chromosome in the SCH group exhibited 23 DMRs compared to the control group. ROS levels in the brain tissues of the SCH group were significantly higher than those in the control group (P < 0.05). The mitochondrial structure in the hippocampus of the SCH group was less intact compared to the CON group.

Subclinical hypothyroidism in pregnant rats may alter the mtDNA methylation pattern in the brains of their offspring, potentially affecting mitochondrial function and structure.

The role of somatic mitochondrial DNA (mtDNA) mutations in leukemogenesis remains poorly characterized. To determine the impact of somatic mtDNA mutations on this process, we assessed the leukemogenic potential of hematopoietic progenitor cells (HPCs) from mtDNA mutator mice (Polg D257A) with or without NMyc overexpression. We observed a higher incidence of spontaneous leukemogenesis in recipients transplanted with heterozygous Polg HPCs and a lower incidence of NMyc-driven leukemia in those with homozygous Polg HPCs compared to controls. Although mtDNA mutations in heterozygous and homozygous HPCs caused similar baseline impairments in mitochondrial function, only heterozygous HPCs responded to and supported altered metabolic demands associated with NMyc overexpression. Homozygous HPCs showed altered glucose utilization with pyruvate dehydrogenase inhibition due to increased phosphorylation, exacerbated by NMyc overexpression. The impaired growth of NMyc-expressing homozygous HPCs was partially rescued by inhibiting pyruvate dehydrogenase kinase, highlighting a relationship between mtDNA mutation burden and metabolic plasticity in leukemogenesis.

Mitochondrial translation is essential to maintain mitochondrial function and energy production. Mutations in genes associated with mitochondrial translation cause several developmental disorders, and immune dysfunction is observed in many such patients. Besides genetic mutations, several antibiotics targeting bacterial ribosomes are well-established to inhibit mitochondrial translation. However, the effect of such antibiotics on different immune cells is not fully understood. Here, we addressed the differential effect of mitochondrial translation inhibition on different subsets of helper T cells (Th) of mice and humans. Inhibition of mitochondrial translation reduced the levels of mitochondrially encoded electron transport chain subunits without affecting their nuclear-encoded counterparts. As a result, mitochondrial oxygen consumption reduced dramatically, but mitochondrial mass was unaffected. Most importantly, we show that inhibition of mitochondrial translation induced apoptosis, specifically in Th2 cells. This increase in apoptosis was associated with higher expression of Bim and Puma, two activators of the intrinsic pathway of apoptosis. We propose that this difference in the sensitivity of Th1 and Th2 cells to mitochondrial translation inhibition reflects the intrinsic metabolic demands of these subtypes. Though Th1 and Th2 cells exhibit similar levels of oxidative phosphorylation, Th1 cells exhibit higher levels of aerobic glycolysis than Th2 cells. Moreover, Th1 cells are more sensitive to the inhibition of glycolysis, while higher concentrations of glycolysis inhibitor 2-deoxyglucose are required to induce cell death in the Th2 lineage. These observations reveal that selection of metabolic pathways for substrate utilization during differentiation of Th1 and Th2 lineages is a fundamental process conserved across species.

Mitochondria, also called 'powerhouse of the cell', is meant for energy generation in eukaryotic cells. This action is performed by mitochondria through the oxidative phosphorylation (OXPHOS) of the respiratory chain (RC). Based on the functioning of the cell, the number of mitochondria varies up to thousands in number. Mutations in the mitochondrial DNA (mtDNA) and/or nuclear DNA (nDNA) genes may lead to the generation of primary mitochondrial disease (PMD) that affects the structure and function of mitochondria. The diagnosis of such mitochondrial diseases occurs in early childhood and it can lead to serious, fetal and multi-organ diseases. Understanding epigenetic events and changes in the pathway can help improve the effectiveness of treatment. However, there are several reasons lack of the disease symptoms (age, sign, symptoms, morbidity and lethality), restricted availability of preclinical models along with extensive phenotypes that hamper the development of efficient drugs. Despite the introduction of new treatments and the encouraging results of treatments and therapies, there is no effective cure for PMD. This article contains information about the changes associated with cytopathic diseases that make possible the analysis of various diseases by genetic techniques. Increasing our understanding of how mitochondrial DNA mutations affect mitochondrial metabolism and subsequently result in neurodegenerative disease will prove vital to the development of targeted therapies and treatments.

Mitochondrial DNA copy number (mtDNA-CN) in human body fluids is widely used as a biomarker of mitochondrial dysfunction in common metabolic diseases. Here we describe protocols to measure cellular and/or cell free (cf)-mtDNA-CN in human peripheral blood and urine. Cellular mtDNA is located inside the mitochondria where it encodes key subunits of the respiratory complexes in mitochondria and is usually normalized with reference to the nuclear genome as the mitochondrial genome to nuclear genome ratio (Mt/N) in either whole blood, peripheral blood mononuclear cells (PBMCs), or whole urine. Cf -mtDNA is usually found outside of the mitochondria, often released following mitochondrial damage, can trigger inflammatory pathways, and is usually measured as mtDNA-CN per volume of the starting material. Here we describe how to (1) separate whole blood into PBMCs, plasma, and serum fractions and whole urine into urinary supernatant and pellet, (2) prepare DNA from each of these fractions, (3) prepare reference standards for absolute quantification, (4) carry out qPCR for either relative or absolute quantification from test samples, (5) analyze qPCR data, and (6) calculate the sample size to adequately power studies. The protocol presented here is suitable for high throughput use and can be modified to quantify mtDNA from other body fluids, human cells, and tissues.

Ovarian tissue cryopreservation has become a promising alternative for fertility preservation in cancer patients, allowing ovarian tissue to be stored for future autotransplantation. Oxidative stress damage occurring during the cryopreservation process may impact tissue quality and function. This study aims to investigate the protective effects and potential mechanisms of Mitoquinone (MitoQ), a mitochondria-targeted derivative of the antioxidant ubiquinone, during the vitrification of ovarian tissue in mice.

KGN cells were treated with various concentrations (0.1, 1, 10, and 50 μM) of MitoQ to determine the optimal concentration. Female ICR mice were divided into three groups: control, conventional vitrification, and MitoQ-supplemented vitrification. Ovarian samples were cryopreserved, thawed, and assessed for tissue morphology using Hematoxylin and Eosin (H&E) staining, and mitochondrial changes using immunofluorescence, transmission electron microscopy, and Western blot analysis. RNA sequencing (RNA-seq) was employed to explore potential protective mechanisms. Autotransplantation experiments were conducted, and the long-term effects of MitoQ on ovarian function were evaluated by counting follicle numbers through H&E staining and measuring serum estradiol and AMH levels using ELISA.

MitoQ at 1 μM was found to be the optimal concentration for maintaining follicular morphology after vitrification. It effectively reduced mitochondrial oxidative damage, preserved mitochondrial morphology, and regulated the expression of mitochondrial dynamics proteins (Drp1 and Mfn2). RNA-seq and Western blot analyses revealed that MitoQ inhibited the p38 MAPK pathway, thereby reducing apoptosis. Additionally, autotransplantation experiments showed that MitoQ treatment significantly increased follicle counts, estradiol (E2), and anti-Müllerian hormone (AMH) levels compared to conventional vitrification.

MitoQ effectively mitigates vitrification-induced oxidative damage, maintains mitochondrial homeostasis, and preserves both follicular reserve and endocrine function. These findings suggest that MitoQ is a valuable adjunct in ovarian tissue cryopreservation and could significantly improve fertility preservation outcomes for cancer patients.

The subcellular distribution of cargoes plays a crucial role in determining cell fate and therapeutic efficacy. However, achieving the precise delivery of therapeutics to specific intracellular targets remains a significant challenge. Here, we present a trimodular and acid/enzyme-gated nanoplatform (TAEN) that undergoes disassembly within acidic endosomes and then is cleaved by lysosomal cathepsin B to facilitate efficient and targeted transport of released cargoes into mitochondria compartments. By utilizing this nanovehicle, we successfully achieve selective sorting of photosensitizer molecules into mitochondria with a colocalization coefficient of up to 0.98, leading to the generation of reactive oxygen species stress specifically within the mitochondria for potent pyroptosis-based cancer therapy. The induction of mitochondrial stress triggers the intrinsic apoptotic pathway as well as caspase-3/gasdermin-E (GSDME) cascade, resulting in an enhanced cancer cell killing efficacy by nearly 2 orders of magnitude as compared to lysosomal stress. Furthermore, due to its superior capability to stimulate both innate and adaptive immune responses, our mitochondria-sorted nanophotosensitizer exhibits robust antitumor immune efficacy in multiple tumor-bearing mice models. This study not only provides insights into engineering nanomedicines for subcellular targeted delivery but also offers a valuable toolkit for advanced research in the field of nanobiology at subcellular resolution.

Nucleoside reverse transcriptase inhibitors (NRTIs) are the backbone of highly active antiretroviral therapy (HAART)-the current standard of care for treating human immunodeficiency virus (HIV) infection. Despite their efficacy, NRTIs cause numerous treatment-limiting adverse effects, including a distinct peripheral neuropathy, called antiretroviral toxic neuropathy (ATN). ATN primarily affects the extremities with shock-like tingling pain, a pins-and-needles prickling sensation, and numbness. Despite its negative impact on patient quality of life, ATN remains poorly understood, which limits treatment options and potential interventions for people living with HIV (PLWH). Elucidating the underlying pathophysiology of NRTI-induced ATN will facilitate the development of effective treatment strategies and improved patient outcomes. In this article, we will comprehensively review ATN in the setting of NRTI treatment for HIV infection.

Mitochondrial DNA (mtDNA) variations affect the efficiency of the electron transport chain and production of reactive oxygen species, contributing to carcinogenesis. The D-loop region of mtDNA has emerged as a variation hotspot region in human neoplasia; however, the potential contribution of these variations in breast cancer risk prediction remains unknown. We investigated the relationship between germline single nucleotide polymorphisms (SNPs) in the entire D-loop region and breast cancer risk in Chinese women. Peripheral blood-isolated mtDNA from 2329 patients with breast cancer and 2328 cancer-free controls was examined for SNPs. In the combined cohort, we used traditional risk factors, susceptibility germline polymorphisms, and logistic regression analysis to evaluate the predictive value of susceptibility variants for breast cancer risk. We calculated the area under the receiver operating characteristic curve (AUC) as a measure. We also measured the content of 8-hydroxy-2'-deoxyguanosine (8-OHdG). Individual polymorphisms SNP573 were significantly associated with breast cancer risk in both the discovery and validation cohorts. In the combined cohort, the AUC of the traditional risk factors was 64.3%; after adding susceptibility variants, the AUC was 64.9% (DeLong test, p = 0.007). 8-OHdG levels were significantly higher in patients with breast cancer than in controls and higher in individuals with SNP573 than in those negative for this variation. Overall, oxidative stress might be associated with the risk of breast cancer, and SNP573 might be associated with oxidative stress. Our results indicate the risk potential of polymorphisms in the D-loop region in breast cancer in Southern China.

Repressing BET proteins' function using bromodomain inhibitors (BETi) has been shown to elicit antitumor effects by regulating the transcription of genes downstream of BRD4. We previously showed that BETi promoted cell death of triple-negative breast cancer (TNBC) cells. Here, we proved that BETi induce altered mitochondrial dynamics fitness in TNBC cells falling in cell death. We demonstrated that BETi treatment downregulated the expression of BCL-2, and proteins involved in mitochondrial fission and increased fused mitochondria. Impaired mitochondrial fission affected oxidative phosphorylation (OXPHOS) inducing the expression of OXPHOS-related genes, SDHa and ATP5a, and increased cell death. Consistently, the amount of mitochondrial DNA and mitochondrial membrane potential (∆Ψm) increased in BETi-treated cells compared to control cells. Lastly, BETi in combination with Metformin reduced cell growth. Our results indicate that mitochondrial dynamics and OXPHOS metabolism support breast cancer proliferation and represent novel BETi downstream targets in TNBC cells.

Spuriopimpinella brachycarpa (Kom.) Kitag., a member of the Apiaceae family, is a perennial aromatic herb native to Northeast Asia with applications in culinary and traditional medicine. Despite its significance, most studies on S. brachycarpa have primarily focused on its phytochemical properties, with limited insights into its molecular and genomic characteristics.

This study presents the sequencing and assembly of the mitochondrial genome (mitogenome) of S. brachycarpa using second- and third-generation high-throughput sequencing technologies. Comprehensive analyses were performed on its structural organization, RNA editing sites, relative synonymous codon usage (RSCU), and repeat sequences. Comparative analyses with closely related species were also conducted.

The mitogenome exhibited a multi-branched structure, with a total length of 523,512 bp and a GC content of 43.37%. Annotation revealed 30 unique protein-coding genes, 21 tRNA genes, and three rRNA genes. Comparative analysis indicated that the S. brachycarpa mitogenome contains structural variations but shares collinear features with other Apiaceae species. We identified 618 potential RNA editing sites involving C-to-U conversions and discovered 59 homologous fragments between the mitogenome and plastome, comprising 8.13% of the mitogenome.

These results enrich the genomic database of Apiaceae, providing valuable insights into the evolutionary relationships and genetic diversity within the family.

For mesenchymal stem cells derived from bone marrow, a controlled reduction in ambient oxygen concentration has been recognized as a facilitator of osteogenic differentiation and the formation of calcium nodules. However, the specific molecular mechanisms underlying this phenotype remain unclear. The aim of this study was to elucidate the impact of hypoxia on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and to explore the involvement of mitophagy and the regulation of mitochondrial dynamics mediated by the mitochondrial dynamic regulatory factor FUN14 domain-containing 1 (FUNDC1). Our findings suggest that FUNDC1 is required for promoting osteogenic differentiation in BMSCs under hypoxic conditions. However, this effect was not dependent on FUNDC1-mediated mitophagy but rather on FUNDC1-mediated regulation of mitochondrial fission. At the mechanistic level, FUNDC1 binds more DNM1L and less OPA1 under hypoxic conditions, leading to an upsurge in mitochondrial division. This heightened mitochondrial division culminates in the increased translocation of Parkin to mitochondria, diminishing its interactions with HIF1α in the cytoplasm and consequently facilitating HIF1α deubiquitination and stabilization. In summary, FUNDC1-regulated mitochondrial division in hypoxic culture emerges as a critical determinant for the translocation of Parkin to mitochondria, ultimately maintaining HIF1α stabilization and promoting osteogenic differentiation.

The increasing use of antibiotics has attracted widespread attention to their environmental risks. However, the phototoxicity of sulfonamide antibiotics to plants remain unclear. In this study, the mechanism of the effect of sulfamethoxazole on photosynthesis of pakchoi cabbage (Brassica rapa var. chinensis) was investigated. The results showed that sulfamethoxazole inhibited the growth of pakchoi cabbage and produced photosynthetic toxicity. The growth inhibition rates increased with concentration, the root and shoot weight were 76.02 % and 47.04 % of the control, respectively, with stay-greens phenomenon in 4 mg·L-1 sulfamethoxazole treatment. Chlorophyll precursors (protoporphyrin IX (Proto IX), Mg-proto IX, and protochlorophyllide (Pchlide), 5-aminolevulinic acid (ALA), and porphobilinogen (PBG)) were 1.38-, 1.26-, 1.12-, 1.71-, and 0.96-fold of the control, respectively; photosynthetic pigments (chlorophyll a, chlorophyll b, and carotenoids) were 1.26-, 1.39-, and 1.03-fold of the control, respectively. Respiration rate was 271.42 % of the control, whereas the net photosynthetic rate was 50.50 % of the control. The maximum photochemical quantum yield of PSII (Fv/Fm), the actual photosynthetic efficiency (Y(II)), the quantum yield of non-regulated energy dissipation (Y(NO)), the apparent electron transfer efficiency of PSII (ETR) under actual light intensity were affected, and chloroplast swelling was observed. Proteomic analysis showed that photosynthesis-related pathways were significantly up-regulated, biological processes such as light response, carbohydrates, and reactive oxygen species were activated. Metabolomic analysis revealed that the tricarboxylic acid cycle (TCA cycle) and carbohydrate catabolism were stimulated significantly (p < 0.05), sugars and amino acids were increased to regulate and enhance the resilience of photosynthesis. While folate biosynthesis and ribosomal pathways were significantly down-regulated, the synthesis and translation processes of amino acids and nucleotides were inhibited.

Leber's hereditary optic neuropathy (LHON) is a debilitating mitochondrial disease associated with mutations in mitochondrial DNA (mtDNA). Unfortunately, the available treatment options for LHON patients are limited due to challenges in mitochondrial replacement. In our study, we reprogramming LHON urine cells into induced pluripotent stem cells (iPSCs) and differentiating them into neural progenitor cells (NPCs) and neurons for disease modeling. Our research revealed that LHON neurons exhibited significantly higher levels of mtDNA mutations and reduced mitochondrial function, confirming the disease phenotype. However, through co-culturing LHON iPSC-derived NPCs with mesenchymal stem cells (MSCs), we observed a remarkable rescue of mutant mtDNA and a significant improvement in mitochondrial metabolic function in LHON neurons. These findings suggest that co-culturing with MSCs can enhance mitochondrial function in LHON NPCs, even after their differentiation into neurons. This discovery holds promise as a potential therapeutic strategy for LHON patients.

Reactive oxygen species (ROS) have an important role in cellular biology, being involved, in a way that depends on their levels, in cell signaling processes or in oxidative stress, probably associated with neurodegenerative and other diseases. Most of the studies about ROS formation were performed in ischemic conditions, and thus, there is limited knowledge about ROS formation in less severe hypoxic conditions. This study investigates neuronal ROS generation and autofluorescence changes in hypoxic conditions, focusing on the involvement of calcium and zinc. Using hippocampal slices from Wistar rats, ROS production was monitored by the permeant fluorescent indicator H2DCFDA under different oxygenation levels. Moderate hypoxia (40% O2) led to a small ROS increase, while severe hypoxia (0% O2) showed a more pronounced rise. KCl-induced depolarization significantly enhanced ROS formation, particularly under severe hypoxia. Inhibition of NMDA receptors reduced ROS generation without affecting autofluorescence, while chelation of zinc ions decreased ROS production and increased flavin adenine dinucleotide (FAD) autofluorescence. These findings suggest that, in hypoxic conditions, ROS formation is mediated by calcium entry through NMDA receptors and also by zinc influxes. Thus, these ions play a crucial role in oxidative stress, which may be related with neurodegenerative diseases associated with ROS dysregulation.

The universe began 13.8 billion years ago, and Earth was born 4.6 billion years ago. Early traces of life were found as soon as 4.1 billion years ago; then, ~200,000 years ago, the human being was born. The evolution of life on earth was to become individual rather than cellular life. The birth of mitochondria made this possible to be the individual life. Since then, individuals have had a limited time of life. It was 1.4 billion years ago that a bacterial cell began living inside an archaeal host cell, a form of endosymbiosis that is the development of eukaryotic cells, which contain a nucleus and other membrane-bound compartments. The bacterium started to provide its host cell with additional energy, and the interaction eventually resulted in a eukaryotic cell, with both archaeal (the host cell) and bacterial (mitochondrial) origins still having genomes. The cells survived high concentrations of oxygen producing more energy inside the cell. Further, the roles of mitochondria in human being's life and aging will be discussed.