Search Results (898)

Background: L-2-hydroxyglutaric aciduria (L2HGA) is a rare autosomal recessive neurometabolic disorder caused by biallelic loss-of-function variants in the L-2-hydroxyglutarate dehydrogenase (L2HGDH) gene, leading to accumulation of L-2-hydroxyglutarate in the brain and other tissues. While various variants have been reported, the pathogenic mechanism of specific variants remains unclear. In this study, we aimed to investigate the molecular consequences of the c.905C>T p.(Pro302Leu) variant, identified in two siblings with typical symptoms of L2HGA, by analyzing its effects on protein localization and enzymatic activity in a cell model. Methods: HA-tagged wild-type and p.(Pro302Leu) mutant L2HGDH constructs were overexpressed in HEK293T cells. We assessed protein expression, subcellular localization, and enzymatic activity using Western blot analysis, immunofluorescence microscopy, and a specific enzyme assay measuring 2,6-dichloroindophenol (DCIP) reduction to assess L2HGDH enzymatic activity. Results: Western blotting showed that wild-type L2HGDH exists primarily in the processed, mature mitochondrial form, whereas the p.(Pro302Leu) mutant remained largely in the unprocessed precursor form. Immunofluorescence and differential centrifugation revealed that wild-type protein localized to mitochondria, while the mutant protein accumulated in the cytoplasm in a diffuse or punctate pattern. Enzyme activity assays demonstrated that the mutant retained <30% of wild-type activity. Conclusions: These findings indicate that the p.(Pro302Leu) variant leads to aggregation of mislocalized protein, thereby impairing L2HGDH function rather than decreasing enzymatic function. This study provides clinical and molecular evidence supporting the pathogenicity of this previously reported mutation and highlights the importance of mitochondrial import for enzyme functionality in L2HGA. Full article

N-lactoyl amino acids (Lac-AAs) are key players that regulate appetite and body weight. The most prominent and well-studied member is N-lactoyl phenylalanine (Lac-Phe), which can be induced by food intake, exercise and metformin treatment. However, its broader metabolic impact remains insufficiently characterized. This study investigates the effects of Lac-Phe on insulin signaling, inflammation, and mitochondrial respiration using HepG2 and differentiated C2C12 cell models, as well as isolated rat brain mitochondria and synaptosomes. Our results demonstrate that Lac-Phe significantly impairs insulin-stimulated phosphorylation of key proteins in the insulin signaling pathway, particularly in skeletal muscle cells, indicating disrupted insulin signaling. Additionally, Lac-Phe exposure increases the secretion of pro-inflammatory cytokines in C2C12 skeletal muscle cells and markedly impairs mitochondrial respiration in HepG2 liver cells and rat brain-derived synaptosomes, but not in isolated mitochondria. These findings highlight potential adverse metabolic effects of Lac-Phe, especially when administered at high concentrations, and underscore the necessity of conducting a comprehensive risk assessment and dose optimization before considering Lac-Phe or related Lac-AAs as therapeutic agents. Our work provides important insights into the molecular liabilities associated with Lac-Phe and calls for further studies to balance its therapeutic promise against possible metabolic risks. Full article

Parkinson’s disease (PD) is characterized by the loss of dopaminergic neurons in the substantia nigra and the presence of α-synuclein-positive inclusions known as Lewy bodies. Synphilin-1 is a protein of unknown function that interacts with α-synuclein and has been shown to exhibit cytoprotective effects in both in vitro and in vivo models. In this study, we investigated whether synphilin-1 is phosphorylated by pathological CDK5 and explored the consequences of this modification. Pathological activation of CDK5 occurs mainly through its association with the calpain-cleaved protein p25. Although CDK5 inhibition protects against neurodegeneration in pharmacological PD models, we now show that p25 levels are increased in PD brains. Furthermore, we demonstrate that CDK5, in conjunction with p25, directly phosphorylates synphilin-1, mainly at serine 566. This phosphorylation reduces synphilin-1′s interaction with SIAH1, leading to reduced ubiquitination and subsequent accumulation. We also observed that CDK5-phosphorylated synphilin-1 exhibits a reduced ability to interact with PINK1 and to promote basal levels of mitophagy. Consistent with these findings, the phosphorylation-mimicking synphilin-1 S566E shows decreased translocation to mitochondria, and synphilin-1 levels are reduced in the mitochondria of PD brains compared to age-matched controls. Finally, synphilin-1 S566E promotes retraction of neuronal processes. Taken together, our results suggest that phosphorylation by CDK5 disrupts synphilin-1′s interactions with its protein partners, rendering it more toxic and impairing its ability to support mitophagy and maintain neuronal process homeostasis. We hypothesize that phosphorylation of synphilin-1 by CDK5 may contribute to the pathogenesis of PD. Full article

Hydrogen sulfide (H₂S) has been established to regulate mitochondrial respiration and ATP production, but whether the regulation is through S-sulfhydration (-SSH) of mitochondrial complexes is not well understood. Recently, H₂S is known to exert diverse and dose-dependent effects on mitochondrial complexes. However, the involvement of S-sulfhydration of each mitochondrial complex and the activities in diabetic hearts have not been revealed. Here, we conducted comprehensive investigations into S-sulfhydration and the activities of mitochondrial complexes I–V in normal and Streptozotocin (STZ)-induced type 1 diabetic (DM) heart mitochondria. Results showed that proteins of H₂S-producing enzymes were downregulated in DM heart mitochondria, which was accompanied by reduced mitochondrial membrane potential (MMP), greater ROS, and lower complex I and V activities, reduced complex V-SSH in DM. In both groups, supplementation with the H₂S donor NaHS increased the S-sulfhydration of all mitochondrial complexes, and the activities of complexes I–III and V were significantly increased but complex IV activity was reduced. Consequently, mitochondrial MMP, ROS, and ATP production were normalized with NaHS in DM, whereas inhibition of H₂S generation increased mitochondrial ROS and reduced MMP via reducing complex activities in both groups. Ischemic reperfusion did not affect NaHS-increment of S-sulfhydration of complexes I–V, but significantly impaired complex V activity in DM. Collectively, H₂S-dependent S-sulfhydration of mitochondrial complexes I–V in normal and DM heart mitochondria were involved in the activation of mitochondrial complexes I–III/V and the inhibition of complex IV, which control cardiac mitochondrial respiration and ATP production. Full article

Ovarian aging is characterized by a gradual decline in both reproductive and endocrine functions, ultimately culminating in the cessation of ovarian activity around the age of 50, when most women experience natural menopause. The decline begins early, as follicular attrition is initiated in utero and continues throughout childhood and reproductive life. Most follicles undergo atresia without progressing through substantial stages of growth. With increasing age, a pronounced reduction occurs in the population of resting follicles within the ovarian reserve, accompanied by a decline in the size of growing follicular cohorts. Around the age of 38, the rate of follicular depletion accelerates, sometimes resulting in diminished ovarian reserve (DOR). The subsequent menopausal transition involves complex, irregular hormonal dynamics, manifesting as increasingly erratic menstrual patterns, primarily driven by fluctuations in circulating estrogens and a rising incidence of anovulatory cycles. In parallel with the progressive depletion of the follicular pool, the serum concentrations of anti-Müllerian hormone (AMH) decline gradually, while reductions in inhibin B levels become more apparent during the late reproductive years. The concomitant decline in both inhibin B and estrogen levels leads to a compensatory rise in circulating follicle-stimulating hormone (FSH) concentrations. Together, these endocrine changes, alongside the eventual exhaustion of the follicular reserve, converge in the onset of menopause, which is defined by the absence of menstruation for twelve consecutive months. The mechanisms contributing to ovarian aging are complex and multifactorial, involving both the oocyte and the somatic cells within the follicular microenvironment. Oxidative stress is thought to play a central role in the age-related decline in oocyte quality, primarily through its harmful effects on mitochondrial DNA integrity and broader aspects of cellular function. Although granulosa cells appear to be relatively more resilient, they are not exempt from age-associated damage, which may impair their hormonal activity and, given their close functional relationship with the oocyte, negatively influence oocyte competence. In addition, histological changes in the ovarian stroma, such as fibrosis and heightened inflammatory responses, are believed to further contribute to the progressive deterioration of ovarian function. A deeper understanding of the biological processes driving ovarian aging has facilitated the development of experimental interventions aimed at extending ovarian functionality. Among these are the autologous transfer of mitochondria and stem cell-based therapies, including the use of exosome-producing cells. Additional approaches involve targeting longevity pathways, such as those modulated by caloric restriction, or employing pharmacological agents with geroprotective properties. While these strategies are supported by compelling experimental data, robust clinical evidence in humans remains limited. Full article

Type 1 diabetes (T1D) is a serious disease which affects millions of people worldwide and is a major factor for vascular contributions to cognitive impairment and dementia (VCID). In this study, we first characterized cognitive and memory impairments, then evaluated their underlying molecular mechanisms, and finally determined sex-dependent effects in male and female mice with streptozotocin (STZ)-induced T1D. Our findings indicated that significant cognitive impairment, memory loss, and vascular dementia occurred in male and female T1D mice. Cerebral artery (CA) blood flow was greatly reduced in the various brain regions tested. ROS generation in isolated cells, mitochondria, and mitochondrial complex III from CA smooth muscle cells (CASMCs) were all increased in T1D. DNA damage and Tau phosphorylation in CASMCs were largely increased. Linear regression analysis revealed that T1D-induced increased blood glucose was highly correlated with increased ROS production and increased VCID. Taken together, we conclude that T1D causes increased mitochondrial complex III ROS production, DNA damage, and Chk2 phosphorylation in CASMC, thereby leading to vascular dementia in both male and female mice; our results further demonstrate that mitochondrial complex III ROS-mediated DNA damage is more significant in male than female mice, which contributes to more serious vascular dementia in the former than the latter. Full article

Migraine is a complex neurological disorder characterized by recurrent headaches and sensory disturbances. Emerging evidence highlights a critical role for mitochondrial dysfunction in migraine pathophysiology, including impairments in oxidative phosphorylation, disruptions in mitochondrial dynamics, and altered biogenesis. Experimental migraine models—ranging from nitroglycerin-induced attacks to inflammatory stimuli—consistently demonstrate mitochondrial swelling, cristae disruption, decreased ATP production, and increased oxidative stress. These findings are accompanied by the altered expression of key mitochondrial regulators such as PGC-1α, Drp1, and Mfn1. Recent studies have further identified distinct metabolic subtypes of mitochondria, including P5CS-containing subsets, which exhibit unique structural and functional profiles, including cristae loss and reduced ATP synthase expression. Notably, the mitochondrial alterations observed in migraine models show remarkable parallels to those described in P5CS-related mitochondrial subsets. These similarities suggest a potential mechanistic link between metabolic reprogramming within mitochondria and migraine pathogenesis. Understanding the contribution of these newly defined mitochondrial populations could offer novel insights into migraine biology and open new avenues for targeted therapeutic strategies. Full article

Background. Myasthenia gravis is an autoimmune neuromuscular disease characterized by fatigue of striated muscles due to impaired neuromuscular transmission. Mitochondrial dysfunction, according to published data, contributes significantly to metabolic abnormalities, oxidative stress and, as a consequence, the persistence of inflammation. MicroRNAs, which are post-transcriptional regulators of expression, are able to contribute to the aberrant functioning of mitochondria. In this study, with the aim of searching for biomarkers at the level of circulating microRNAs and proteins, the expression of three microRNAs was analyzed and the concentration of mitochondrial proteins was measured in the blood plasma of patients with myasthenia gravis (n = 49) in comparison with healthy volunteers (n = 31). Methods. Expression analysis was performed by RT-PCR, mathematical data processing was carried out using the Livak method, and protein concentration was determined by enzyme immunoassay. Results. Our plasma expression analysis revealed a statistically significant increase in hsa-miR-194-5p expression (Log10 Fold Change = 1.46, p-value < 0.0001) and a statistically significant decrease in hsa-miR-148a-3p expression (Log10 Fold Change = −0.65, p-value = 0.02). A statistically significant decrease in plasma COQ10A concentration was also found (0.911 [0.439; 1.608] versus 1.815 [1.033; 2.916] for myasthenia gravis and controls, respectively, p-value = 0.01). Conclusion. Our data suggest hsa-miR-148a-3p and hsa-miR-194-5p, as well as COQ10A, as potential biomarkers of mitochondrial dysfunction in myasthenia gravis. Full article

Renal oncocytoma (RO) is a benign renal neoplasm characterized by dense accumulation of dysfunctional mitochondria possibly resulting from increased mitochondrial biogenesis and decreased mitophagy; however, the mechanisms controlling these mitochondrial changes are unclear. ROs harbor recurrent inactivating mutations in mitochondrial genes encoding the Electron Transport Chain (ETC) Complex I, and we hypothesize that Complex I loss in ROs directly impairs mitophagy. Our analysis of ROs and normal kidney (NK) tissues shows that a significant portion (8 out of 17) of ROs have mtDNA Complex I loss-of-function mutations with high variant allele frequency (>50%). ROs indeed exhibit reduced Complex I expression and activity. Analysis of the various steps of mitophagy pathway demonstrates that AMPK activation in ROs leads to induction of mitochondrial biogenesis, autophagy, and formation of autophagosomes. However, the subsequent steps involving lysosome biogenesis and function are defective, resulting in an overall inhibition of mitophagy. Inhibiting Complex I in a normal kidney cell line recapitulated the observed lysosomal and mitophagy defects. Our data suggest Complex I loss in RO results in defective mitophagy due to lysosomal loss and dysfunction. Full article

Sepsis-induced myocardial injury is age-related and leads to increased mortality. Considering the importance of mitochondrial dysfunction in cardiac impairment, we aimed to investigate whether aging exacerbates the cardiac mitochondrial metabolic response to inflammation, thus leading to increased cardiac dysfunction in the elderly. Cecal ligation and puncture (CLP) was conducted in young adult (12–18 weeks) and aged (19–21 months) male C57BL/6 mice. Cardiac function was detected 20 h post-CLP. Additionally, cardiomyocytes isolated from young adult and aged male mice were used for assessments of mitochondrial respiratory function +/– TNFα or LPS. Protein levels of oxidative phosphorylation (OXPHOS), NADPH oxidase (NOX)2, NOX4, phosphor-STAT3 and STAT3 were determined in mouse hearts 24 h post-CLP and in cardiomyocytes following inflammatory stimuli. CLP significantly reduced cardiac contractility in both young and aged mice, with a higher incidence and greater severity of cardiac functional depression in the older group. Mitochondrial respiratory capacity was decreased in cardiomyocytes derived from aged mice, with increased susceptible to inflammatory toxic effects compared to those from young adult mice. The age-dependent changes were observed in myocardial OXPHOS complexes and NOX4. Importantly, CLP led to a significant increase in OXPHOS protein levels in the hearts of older mice, suggesting a possible compensatory response to decreased mitochondrial metabolic function and a greater potential for reactive oxygen species (ROS) generation. Our findings highlight that the response of aging-impaired mitochondria to inflammation may underlie the worsened cardiac functional depression in the aged group during sepsis. Full article

Background/Objectives: Male infertility is a major health concern with a complex etiopathology, yet a substantial proportion of cases remain idiopathic. Mitochondrial dysfunction and non-coding RNA (ncRNA) deregulation have both been implicated in impaired spermatogenesis, but their interplay remains poorly understood. This study aimed to identify infertility-specific variants in ncRNAs that affect mitochondrial dynamics and homeostasis and to explore their roles. Methods: Whole-genome sequencing (WGS) was performed on genomic DNA samples from teratozoospermic, asthenozoospermic, oligozoospermic, and normozoospermic men. Variants uniquely present in infertile individuals and mapped to ncRNAs that affect mitochondrial dynamics were selected and prioritized using bioinformatics tools. An independent transcriptomic validation was conducted using RNA-sequencing data from testicular biopsies of men with non-obstructive azoospermia (NOA) to determine whether the ncRNAs harboring WGS-derived variants were transcriptionally altered. Results: We identified several infertility-specific variants located in lncRNAs known to interact with mitochondrial regulators, including GAS5, HOTAIR, PVT1, MEG3, and CDKN2B-AS1. Transcriptomic analysis confirmed significant deregulation of these lncRNAs in azoospermic testicular samples. Bioinformatic analysis also implicated the disruption of lncRNA–miRNA–mitochondria networks, potentially contributing to mitochondrial membrane potential loss, elevated reactive oxygen species (ROS) production, impaired mitophagy, and germ cell apoptosis. Conclusions: Our integrative genomic and transcriptomic analysis highlights lncRNA–mitochondrial gene interactions as a novel regulatory layer in male infertility, while the identified lncRNAs hold promise as biomarkers and therapeutic targets. However, future functional studies are warranted to elucidate their mechanistic roles and potential for clinical translation in reproductive medicine. Full article

Mitochondria are central to energy production and redox regulation in spermatozoa, supporting key functions such as progressive motility, capacitation, and the acrosome reaction. These processes are essential for successful fertilization and embryo development. However, species-specific differences exist in the reliance on oxidative phosphorylation versus glycolysis. Mitochondria also generate reactive oxygen species, which at physiological levels aid in sperm function but can cause oxidative stress and damage when overproduced. Mitochondrial dysfunction and excessive ROS can impair membrane potential, induce apoptosis, and damage nuclear and mitochondrial DNA, ultimately compromising sperm quality. Sperm mitochondrial DNA is highly susceptible to mutations and deletions, contributing to reduced motility and fertility. Targeted antioxidant strategies have emerged as promising therapeutic interventions to mitigate oxidative damage. This article provides a comprehensive overview of mitochondrial regulation in spermatozoa, the consequences of redox imbalance, and the potential of mitochondria-targeted antioxidants to improve sperm function and male fertility outcomes. The paper aims to deepen our understanding of mitochondrial roles in sperm physiology and contribute to the advancement of strategies for addressing male infertility. Full article

Insulin resistance is a fundamental pathophysiological mechanism contributing to the development of type 2 diabetes and metabolic syndrome. Recently, attention has focused on mitochondria’s role in glucose and lipid metabolism. Mitochondrial dysfunction is strongly associated with impaired energy metabolism and elevated oxidative stress. We investigated the mitochondrial DNA (mtDNA) copy number in subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT) in insulin-sensitive (IS) and insulin-resistant (IR) individuals. Twenty-seven paired adipose tissue biopsies were obtained during elective abdominal surgery. DNA and RNA were extracted, and mtDNA copy number was quantified using Real-Time PCR. We found that mtDNA content in VAT was approximately two-fold lower than in SAT. Furthermore, in IR individuals, mtDNA copy number was significantly reduced in both SAT and VAT compared to IS subjects. A strong positive correlation was observed between mtDNA content in VAT and body mass index (BMI), and a negative correlation was found with the QUICKI index. Additionally, mtDNA copy number in VAT positively correlated with the expression of several genes involved in insulin signalling, lipid metabolism, and other metabolic pathways. These findings underscore the central role of mitochondrial function in VAT in the context of metabolic disorders and suggest that targeting mitochondrial regulation in this tissue may represent a promising therapeutic approach. Full article

Parkinson’s disease (PD) is a common neurodegenerative disorder with substantial global impact. Although current therapies can provide symptomatic relief, they are often associated with high costs and adverse effects. Natural compounds with a history of traditional medicinal use have emerged as promising alternatives. In this study, we investigated the therapeutic potential and underlying mechanisms of berberine in both cellular and animal models of PD. In vitro, SH-SY5Y cells exposed to 6-hydroxydopamine (6-OHDA) exhibited decreased viability and increased oxidative stress, both of which were significantly alleviated by berberine treatment based on cell viability assays and DCFH-DA staining. Western blot analysis revealed that berberine modulated the AMPK–PGC-1α–SIRT1 signaling pathway and restored the expression of autophagy-related proteins LC3B and P62, suggesting that berberine could improve mitochondrial function and autophagy balance. In vivo studies using a 6-OHDA-induced PD mouse model further confirmed these effects, showing that berberine could improve motor function and lead to molecular changes consistent with in vitro studies. Additionally, safety evaluations indicated no significant hepatotoxicity based on AST and ALT levels. Body weight also remained stable throughout treatment. Collectively, our findings suggest that berberine can not only alleviate PD-related symptoms but also target key pathological mechanisms, supporting its potential as a therapeutic candidate for PD and other neurodegenerative diseases. Full article

Cirrhosis remains a significant global health burden, responsible for nearly 4% of annual deaths worldwide. Despite progress in antiviral therapies and public health measures, its prevalence has plateaued, particularly in regions affected by viral hepatitis, alcohol misuse, and metabolic syndrome. This review presents a comprehensive synthesis of the multifactorial drivers of cirrhosis, including hepatocyte injury, liver stellate cell activation, and immune-mediated inflammation. The emphasis is on the central role of metabolic dysfunction, characterized by mitochondrial impairment, altered lipid and glucose metabolism, hormonal imbalance, and systemic inflammation, in exacerbating disease progression. While current therapies may slow the progression of early-stage disease, they are very often ineffective in reversing established fibrosis. Emerging molecular strategies offer promising alternatives by targeting key pathogenic pathways. These include AMPK activators (e.g., metformin, AICAR), FGF21 analogs, and mitochondria-targeted agents (e.g., MitoQ, urolithin A, NAD+ precursors) to restore bioenergetic balance and reduce oxidative stress. Other approaches, such as mesenchymal stem cell therapy, inflammasome inhibition, and hormonal modulation, aim to suppress fibrogenesis and restore liver homeostasis. The integration of systems biology and multi-omics profiling supports patient stratification and precision medicine. This review highlights a shift toward mechanism-based interventions that have the potential to alter cirrhosis outcomes and improve patient survival. Full article