Search Results (474)

Microproteins are small polypeptides translated from short open reading frames (sORFs) that typically encode < 100 amino acids. Advances in ribosome profiling, mass spectrometry, and computational prediction have revealed a growing number of microproteins that play important roles in cellular metabolism, organelle function, and stress adaptation; however, these were considered non-coding or functionally insignificant. At the mitochondrial level, microproteins, such as MTLN (also known as mitoregulin/MOXI) and BRAWNIN, contribute to lipid oxidation, oxidative phosphorylation efficiency, and respiratory chain assembly. Other microproteins at the endoplasmic reticulum–mitochondria interface, including PIGBOS and several muscle-resident regulators of calcium cycling, show diverse biological contexts in which these microproteins act. A subset of microproteins responds to nutrient availability. For example, SMIM26 modulates mitochondrial complex I translation under serine limitation, and non-coding RNA expressed in mesoderm-inducing cells encoded with peptides facilitates glucose uptake during differentiation, indicating that some microproteins can affect metabolic adaptation through localized translational- or organelle-level mechanisms. Rather than functioning as primary nutrient sensors, these microproteins complement classical nutrient-responsive pathways such as AMP-activated protein kinase-, peroxisome proliferator-activated receptor-, and carbohydrate response element binding protein-mediated signaling. As the catalog of microproteins continues to expand, integrating proteogenomics, nutrient biology, and functional studies will be central to defining their physiological relevance; these integrative approaches will also help reveal their potential applications in metabolic health. Full article

Doxorubicin (DOX), a clinical broad-spectrum anthracycline chemotherapeutic agent, induces dose-dependent cardiotoxicity that progresses to heart failure (HF), thereby severely limiting its clinical application. Mitochondrial dysfunction and oxidative stress dysregulation are core pathological mechanisms underlying DOX-induced myocardial injury. This study aimed to investigate the protective effect and underlying mechanism of Cistanche deserticola polysaccharides (CDPs) against DOX-induced cardiotoxicity in C57BL/6J mice. Compared with the DOX model group, CDPs significantly increased left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS), and reduced the activities of serum creatine kinase (CK), creatine kinase-MB (CK-MB), and lactate dehydrogenase (LDH). Additionally, CDPs notably decreased the malondialdehyde (MDA) levels in serum and myocardial tissue, while significantly enhancing the activities of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px). Moreover, CDPs ameliorated mitochondrial swelling and crista fracture, upregulated the expression of mitochondrial respiratory chain complex-related genes, and increased adenosine triphosphate (ATP) production. In conclusion, CDPs alleviate DOX-induced cardiotoxicity and protect cardiac function by inhibiting myocardial oxidative stress and improving mitochondrial function, which provides a potential therapeutic strategy for preventing DOX-related cardiotoxicity. Full article

Human cell-based assays for neurotoxicity (NT) and developmental neurotoxicity (DNT) have reached a high level of readiness, but some tests require improvements in the specificity and sensitivity at which mitochondrial toxicants are detected. This study aimed to optimize the PeriTox assay, which uses peripheral neurons (PNs) and predicts the potential of chemicals to trigger peripheral neuropathies. By introducing a glucose-to-galactose switch in the medium composition, cells were forced to rely on mitochondrial respiration. Using pre-differentiated PNs cultured in either glucose (Glc) or galactose (Gal), we observed no major differences in baseline phenotype, gene expression, neurite outgrowth, or total ATP content. However, a marked metabolic shift was confirmed by the increased oxygen consumption in Gal conditions. Based on measurements of neurite growth and ATP levels, Gal-adapted neurons showed a heightened sensitivity, up to 7500-fold, to a range of mitochondrial respiratory chain (MRC) inhibitors. The sensitivity shift was high for inhibitors of MRC complexes I and III and modest or absent for unrelated compounds such as proteasome inhibitors or cytoskeletal poisons. For complex I-III inhibitors, the enhanced detection of mitochondrial neurotoxicants was coupled with a more accurate distinction between cytotoxic and neurite-specific effects, i.e., an improved assay specificity. In conclusion, our study on 39 compounds suggests that running the PeriTox assay in galactose increases its sensitivity and specificity for several mitochondrial toxicants, while no general disadvantages or shortcomings were observed. The modified version (PeriTox-M) may increase the performance of in vitro test batteries for scientific and regulatory applications. Full article

Inhibition of respiratory chain complex I (NADH dehydrogenase) is a widely encountered biochemical consequence of drug intoxication and a primary consequence of mtDNA mutations and other mitochondrial defects. In an organ-selective form, it is also deployed as antidiabetic pharmacological treatment. Complex I inhibition evokes a pronounced metabolic reprogramming of uncertain purposefulness, as in several cases, anabolism appears to be fostered in a state of bioenergetic shortage. A hallmark of complex I inhibition is the enhanced biosynthesis of serine, usually accompanied by an induction of folate-converting enzymes. Here, we have revisited the differential transcriptional induction of these metabolic pathways in three published models of selective complex I inhibition: MPP-treated neuronal cells, methionine-restricted rats, and patient fibroblasts harboring an NDUFS2 mutation. We find that in a coupled fashion, serinogenesis and circular folate cycling provide an unrecognized alternative pathway of complete glucose oxidation that is mostly dependent on NADP instead of the canonic NAD cofactor (NADP:NAD ≈ 2:1) and thus evades the shortage of oxidized NAD produced by complex I inhibition. In contrast, serine utilization for anabolic purposes and C₁-folate provision for S-adenosyl-methionine production and transsulfuration cannot explain the observed transcriptional patterns, while C₁-folate provision for purine biosynthesis did occur in some models, albeit not universally. We conclude that catabolic glucose oxidation to CO₂, linked with NADPH production for indirect downstream respiration through fatty acid cycling, is the general purpose of the remarkably strong induction of serinogenesis after complex I inhibition. Full article

Mitochondrial DNA (mtDNA) mutations are prevalent across cancer genomes, and growing evidence implicates their multifaceted role in energy metabolism with tumorigenesis. Ovarian cancer, in particular, demonstrates high mtDNA copy numbers and increased incidences of truncating and missense mtDNA mutations, with heteroplasmy levels predictive of prognosis. This review provides a comprehensive description of published mtDNA sequencing data in ovarian cancer, the majority being high-grade serous samples, encompassing both coding and non-coding regions. MtDNA mutations within non-coding regions, such as the D-loop control region, can affect mtDNA replication and transcription, hence affecting overall mtDNA copy numbers, while mtDNA mutations within coding regions can directly impact respiratory complex function and downstream metabolic pathways. MtDNA mutations may serve as clinically valuable diagnostic biomarkers for ovarian cancer and predictors for chemoresistance. We also explore ongoing efforts to deepen our understanding of mitochondrial oncogenetics through the creation of novel cancer models enabled by mitochondrial gene editing techniques. Developing robust human ovarian cancer cell models will be critical to elucidate mechanistic and phenotypic consequences of mtDNA mutations, assess drug response and resistance and identify new therapeutic targets to advance precision oncology in this emerging field. Full article

Reactive oxygen species (ROS), inevitable by-products of aerobic metabolism, act both as regulators of signaling pathways and as mediators of oxidative stress and aging-related damage. Protein oxidative post-translational modifications (Ox-PTMs) are recognized hallmarks of aging and metabolic decline, yet the persistence of protein oxidation under different physiological conditions, such as age and diet, remains unclear. Here, we applied proteomics to mitochondrial and membrane-enriched fractions of male Fischer 344 rat cerebrum and heart, comparing Ox-PTMs across young and aged animals subjected to ad libitum nutrition (AL) or calorie restriction (CR). We identified 139 mitochondrial and membrane-associated proteins consistently exhibiting high levels of oxidation, including tricarboxylic acid (TCA) cycle enzymes, respiratory chain subunits, ATP synthase components, cytoskeletal proteins, and synaptic vesicle regulators. Functional enrichment and network analyses revealed that oxidized proteins clustered in modules related to mitochondrial energy metabolism, membrane transport, and excitation–contraction coupling. Notably, many proteins remained persistently oxidized, predominantly as mono-oxidation, without significant changes during aging or CR. Moreover, the enzymatic activity of mitochondrial complexes was not only preserved but significantly enhanced in specific contexts, and the structural integrity of the respiratory chain was maintained. These findings indicate a dual strategy for coping with oxidative stress: CR reduces ROS production to limit oxidative burden, while protein and network robustness enable functional adaptation to persistent oxidation, collectively shaping mitochondrial function and cellular homeostasis under differing physiological conditions. Full article

Altered mitochondrial function is implicated in disorders characterized by prefrontal cortex activation deficits, including attention deficit hyperactivity disorder (ADHD). The expression of mitochondrial DNA-coded respiratory chain complex I genes (ND1–ND6) in the prefrontal cortex of ADHD animal models was estimated in the present study. ND gene expression was assessed in two publicly available datasets: GSE117357 (Adgrl3 knockout mice) and GSE173926 (MYT1L heterozygous knockout mice). Additionally, we measured NDs gene expression via qPCR in dopamine transporter knockout (DAT-KO) rats and their heterozygous (DAT-Het) littermates. Transcriptomic analysis revealed consistent ND1–ND6 expression profiles across both datasets, and co-expression among ND genes was significantly enhanced in ADHD models compared to wild-type controls. Whole-transcriptome analysis identified associations between ND3 and ND4L expression and genes involved in neural tissue-specific processes, exclusively in ADHD models. In DAT-KO and DAT-Het rats, NDs gene co-expression increased. Furthermore, in DAT-Het rats, which do not exhibit hyperactivity, the upregulation of ND4L expression relative to wild-type littermates was demonstrated. The observed changes in mitochondrial complex I gene co-expression in ADHD models suggest mitochondria may serve as a prospective target for adjuvant therapy. These findings highlight the need for further investigation into mitochondrial contributions to ADHD pathophysiology. Full article

Astaxanthin (AST) is a xanthophyll carotenoid known for its cardioprotective effects. In this study, we investigated the impact of AST on the survival of AC16 human cardiomyocytes under cardiotoxic conditions induced by hydrogen peroxide (H₂O₂) and doxorubicin (DOX). We assessed a series of parameters associated with cell death signaling, including: changes in cytosolic Ca²⁺ levels and reactive oxygen species (ROS) production; alterations in mitochondrial function (membrane potential ΔΨm and the content of key subunits of complexes I and II); and the levels of key apoptotic and ER stress markers. Our findings show that AST prevented the cytotoxic effects of both H₂O₂ and DOX. In the presence of AST, the number of viable cells increased, while Ca²⁺ levels, ROS production, and ΔΨm remained comparable to those in the control group. Furthermore, AST prevented the H₂O₂-induced decrease in the levels of the main subunits of respiratory chain complexes I and II. AST prevented the H₂O₂-induced increase in the levels of apoptotic caspases-8 and -3. It also protected against ER stress by counteracting the H₂O₂-mediated upregulation of BIP, CHOP, and ERO1α proteins. These results lead us to conclude that AST exerts a protective effect by inhibiting mitochondrial dysfunction. Full article

Although experimental evidence indicates that mitochondrial collapse is a common effect of both Chagas disease and post-ischemic heart failure and that cardiac anatomy and function are partially restored by stem cell therapy, the responsible molecular mechanisms are still under debate. Gene expression data from our publicly accessible transcriptomic dataset obtained by profiling the left ventricle myocardia of mouse models of Chagas disease and post-ischemic heart failure were re-analyzed from the perspective of the Genomic Fabric Paradigm. In addition to the regulation of the gene expression levels, we determined the changes in the strength of the homeostatic control of transcript abundance and the remodeling of the gene networks responsible for the mitochondrial respiration. The analysis revealed that most of the mitochondrial genes assigned to the five complexes of the respiratory chain were significantly downregulated by both Chagas disease and ischemia but exhibited outstanding recovery of the normal expression levels following direct injection of bone-marrow-derived stem cells. However, instead of regaining the original expression control and gene networking, the treatment induced novel mitochondrial arrangements, suggesting that multiple transcriptomic topologies might be compatible with any given physiological or pathological state. This study confirmed several established mechanisms and identified novel gene expression signals, especially Cox4i2, Cox6b1, Cox7b, Ndufb11, and Tmem186, that warrant further investigations. Their broad rescue with cell therapy underscores mitochondria as a convergent, tractable target for cardiac repair. Full article

Gaucher disease (GD) is an autosomal recessive metabolic disorder caused by pathogenic variants in the GBA1 gene, which encodes the lysosomal hydrolase β-glucocerebrosidase (GCase). The pathogenic defects result in a misfolded protein, which can trigger endoplasmic reticulum stress and an unfolded protein response within the affected cells. The reduced enzyme activity leads to accumulation of its substrates, glucosylceramide (GlcCer) and glucosylsphingosine (GlcSph), within lysosomes or macrophages and with prominent disease manifestations in reticuloendothelial tissues such as liver, spleen and bone marrow. GCase defects alter both the mitochondria and the lysosome. In the lysosome, reduced GCase activity leads to glycosphingolipid build-up, disrupting lysosomal function and autophagy, thereby activating α-synuclein accumulation. GCase can also be imported into the mitochondria, where it fosters the integrity and function of mitochondrial respiratory chain (MRC) complex I. Thus, the reduced GCase activity impairs the normal mitochondrial function and increases oxidative stress in this organelle, which may contribute to cell death. However, further studies are required to confirm this mechanism of MRC dysfunction. In this review we have systematically evaluated the evidence for oxidative stress in individuals affected by GD, as well as the currently available therapies and adjunctive therapies. Therapies targeting oxidative stress may prove useful as adjuvant treatments for GD. Full article

Sepsis remains one of the major challenges in modern intensive care, characterized by high mortality and complex metabolic and immunological disturbances. Given the limited effectiveness of current therapeutic strategies, increasing attention has been directed toward supportive interventions aimed at restoring metabolic homeostasis. Particular interest has been focused on selected vitamins that exhibit pleiotropic biological effects. Thus, we summarized the current evidence on the role of selected vitamins (C, D, B1, B9, B12) in the treatment and supportive management of sepsis, highlighting their mechanisms of action, potential clinical benefits, and limitations derived from available studies. A comprehensive analysis of the literature was performed, including clinical trials and meta-analyses evaluating the efficacy of vitamin supplementation in sepsis, with particular emphasis on combined interventions and randomized controlled trials in severe sepsis and septic shock. Vitamin D might demonstrate the greatest therapeutic potential, particularly in patients with severe sepsis and respiratory failure, with benefits associated with achieving appropriate therapeutic concentrations. Thiamine (vitamin B1) appears to provide potential advantages primarily in deficient patients, improving mitochondrial function and reducing the risk of renal failure. Evidence regarding folic acid (vitamin B9) and cobalamin (vitamin B12) remains inconclusive, as both deficiency and elevated serum levels have been linked to adverse outcomes. Vitamin C, despite its well-documented antioxidant and microcirculatory effects, has not yet shown consistent evidence of mortality reduction. In conclusion, current evidence suggests that vitamin supplementation might represent an adjunct to standard sepsis therapy, particularly within a personalized approach that considers nutritional status and metabolic phenotype. The development of standardized dosing protocols and well-designed clinical trials is essential to determine the efficacy and safety of phenotype-driven individualized approaches in sepsis management. Full article

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) closely interacts with host cellular mechanisms, with mitochondria playing a crucial role in this process. As essential organelles that control cellular energy production, apoptosis, reactive oxygen species (ROS) metabolism, and innate immune responses, mitochondria are vital to the development of COVID-19. However, the exact molecular interactions between mitochondria and SARS-CoV-2 remain under active investigation. Gaining a comprehensive understanding of mitochondrial involvement in SARS-CoV-2 infection is therefore essential for uncovering complex disease mechanisms, identifying prognostic biomarkers, and developing effective treatments. Ultimately, exploring these virus–host interactions may provide new insights into the fundamental and complex aspects of mitochondrial physiology and pathophysiology. Full article

Obstructive nephropathy is a common clinical condition caused by urinary retention. After urine flow is restored, kidney function is recovered. However, the effectiveness of this process can be influenced by many factors, including the age of the patient. In this study, we analyzed the following parameters in young and old rats subjected to a 3-day reversible unilateral ureteral obstruction (R-UUO): AKI severity, renal tissue proliferation and histology, inflammatory and fibrosis marker expression, as well as autophagosomal-lysosomal and mitochondrial function. Compared to old rats, young animals exhibited more pronounced renal tissue proliferation and higher expression of profibrotic markers (Col1a1, Fn1, Tgfb1, MMP2), but diminished expression of pro-inflammatory markers (Il1b, Tnfa, Cd32) in response to R-UUO. Additionally, young rats showed more pronounced activity of autophagy, as indicated by increased beclin-1 levels. R-UUO induced severe damage to the mitochondrial respiratory chain in old animals, as indicated by reduced complex I, IV, cytochrome c, VDAC protein levels, and impaired mitochondrial biogenesis (associated with decreased Pgc1a mRNA expression). Thus, we demonstrated that despite restored urine outflow, kidneys exhibited autophagy activation, inflammatory response, and mitochondrial dysfunction after R-UUO. Negative alterations in the kidney were age-dependent indicating necessity for therapeutic strategies optimization for patients of different ages. Full article

Schizophrenia is a highly polygenic and clinically heterogeneous disorder. In this paper, we first review layer-specific evidence across genetics, epigenetics, transcriptomics, proteomics, and patient-derived induced pluripotent stem cell (iPSC) models, then integrate cross-layer findings. Genetics research identifies widespread risk architecture. Hundreds of loci from common, rare, and CNV analyses. Epigenetics reveals disease-associated DNA methylation and histone-mark changes. These occur at neuronally active enhancers and promoters, together with chromatin contacts that link non-coding risk to target genes. Transcriptomics show broad differential expression, isoform-level dysregulation, and disrupted co-expression modules. These alterations span synaptic signaling, mitochondrial bioenergetics, and immune programs. Proteomics demonstrates coordinated decreases in postsynaptic scaffold and mitochondrial respiratory-chain proteins in cortex, with complementary inflammatory signatures in serum/plasma. iPSC models recapitulate disease-relevant phenotypes: including fewer synaptic puncta and excitatory postsynaptic currents, electrophysiological immaturity, oxidative stress, and progenitor vulnerability. These same models show partial rescue under targeted perturbations. Integration across layers highlights convergent pathways repeatedly supported by ≥3 independent data types: synaptic signaling, immune/complement regulation, mitochondrial/energetic function, neurodevelopmental programs and cell-adhesion complexes. Within these axes, several cross-layer convergence genes/proteins (e.g., DLG4/PSD-95, C4A, RELN, NRXN1/NLGN1, OXPHOS subunits, POU3F2/BRN2, PTN) recur across cohorts and modalities. Framing results through cross-layer and shared-pathway convergence organizes heterogeneous evidence and prioritizes targets for mechanistic dissection, biomarker development, and translational follow-up. Full article

Mitochondria possess their own genome, which encodes subunits of the electron transport chain, rendering mitochondrial protein translation essential for cellular energy metabolism. Mitochondrial dysfunction affects nuclear transcription through the retrograde response. We applied RNA-seq to investigate whether and how the inhibition of mitochondrial translation by chloramphenicol (CAP) affects transcriptome regulation in proliferating or stationary-phase cells of Schizosaccharomyces pombe growing in fermentative or respiratory media. Stationary-phase cells in glucose medium exhibited the strongest transcriptome response to CAP, characterized by expression signatures similar to those observed under other stresses, including the retrograde response. The induced genes were also significantly enriched in cytoplasmic carbon metabolism pathways, reflecting a transcriptional reprogramming from respiration to fermentation. The transcription factors Scr1 and Rst2, regulators of carbon catabolite repression (CCR), controlled a common set of carbon metabolism genes in CAP-treated stationary-phase cells, and they showed opposing effects on the lifespan of these cells. Rst2 was required for the induction of carbon metabolism genes and maintained nuclear localization in CAP-treated stationary-phase cells. A systematic genetic interaction screen revealed functional relationships of Rst2 with processes related to stress and starvation responses. These findings uncover a complex transcriptional program in stationary-phase cells that adapt to inhibited mitochondrial translation, including stress- and retrograde-like responses, contributions of the CCR factors Scr1 and Rst2, and adjustment of carbon metabolism to deal with mitochondrial dysfunction. Full article