Search Results (119)

Air pollution, particularly from fine and ultrafine particulate matter (PM), has been increasingly associated with cardiovascular diseases. Ultrafine carbon, a component of ultrafine PM widely used in industrial settings, is both an environmental and occupational hazard. But the cardiac toxicity of repeated inhalation exposure to ultrafine carbon black (CB) remains unclear. In this study, we investigated how repeated inhalation of CB affects cardiac mitochondrial function, focusing on metabolic pathways and regulatory mechanisms involved in energy production. Male C57BL/6J mice were exposed to either filtered air or CB aerosols (10 mg/m³) for four consecutive days. Cardiac tissues were collected and analyzed to assess changes in metabolic enzyme activity, protein expression, and mitochondrial function using Western blotting, enzymatic assays, and immunoprecipitation. Despite there being few changes in overall protein expression levels, we observed significant impairments in fatty acid oxidation, increased glucose oxidation, and disrupted electron transport chain (ETC) supercomplex assembly, particularly in Complexes III and IV. These changes were accompanied by increased hyperacetylation of mitochondrial proteins and elevated levels of GCN5L1, a mitochondrial acetyltransferase. We also found increased lipid peroxidation and hyperacetylation of antioxidant enzyme SOD2 at the K-122 site, which reflects reduced enzymatic activity contributing to oxidative stress. Our findings suggest that repeated CB inhalation leads to mitochondrial dysfunction in the heart by dysregulating substrate utilization, impairing ETC activities, and weakening antioxidant defenses primarily through lysine acetylation. These findings reveal a potential role of key post-translational mechanisms in environmental particulate exposure to mitochondrial impairment and provide a potential therapeutic target for CB-induced cardiotoxicity. Full article

The mechanistic underlying the favorable meat quality of Tibetan pigs has not been fully elucidated. This study integrated flavor chemistry, histomorphology, and proteomics to explore the structural and molecular features of their meat. Longissimus dorsi samples from Tibetan and Duroc pigs (n = 6 each biological replicates) were quantitatively analyzed for amino acid profiling, histological assessment, and proteomic characteristic. Statistical approaches included weighted correlation network analysis, t-tests, and functional enrichment. Tibetan pork contained 34 mg/100g more total free amino acids, notably sweet-tasting Ala (+49.2%) and Thr (+32.2%). Muscle fiber density was >250% higher and diameter > 30% smaller, indicating finer texture. Proteomics revealed 149 upregulated proteins, including 57 mitochondrial differentially expressed proteins (DEPs)—11 of which belonged to electron transport chain complexes (e.g., NDUFAB1, COX2). The significant enrichment of oxidative phosphorylation pathways may be associated with mitochondrial efficient energy metabolism under hypoxic in Tibetan pigs, potentially linking to the breed’s unique meat characteristics. Ala levels showed strong correlations with metabolic and structural protein modules. The finer fibers and mitochondrial protein profile of Tibetan pigs contribute to higher amino acid content and meat quality. This structural–metabolic–flavor axis supports both hypoxia adaptation and high meat quality. Given the central role of mitochondrial electron transport chain (ETC) proteins in energy metabolism and Ala in flavor presentation, their synergistic action provides a molecular bridge between hypoxia adaptation and meat quality. Therefore, this study suggests that ETC and Ala may serve as key biomarkers for meat quality differences, offering new perspectives for meat quality research. Full article

Reactive oxygen species (ROS) are formed by the incomplete reduction of oxygen and play a crucial role in both physiological function and pathological process, being controlled by enzymatic and non-enzymatic antioxidant systems. However, excessive ROS production can exceed the body’s antioxidant capacity, resulting in oxidative stress and causing cell death and oxidation of important biomolecules. In this context, the inhibition and/or modulation of ROS has been shown to be effective in reducing pain, oxidative stress, and inflammation. Among ROS, superoxide anion (O₂^•−) is the first free radical to be formed through the mitochondrial electron transport chain (ETC) or by specific enzymes systems, such as the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) complex. O₂^•− plays a significant role in the development and maintenance of pain associated with inflammatory conditions through direct or indirect activation of primary nociceptive neurons and, consequently, peripheral and central sensitization. Experimentally, potassium superoxide (KO₂, a O₂^●− donor) is used to initiate O₂^●− mediated inflammatory and nociceptive responses, making it important for studying the mechanisms associated with ROS-induced pain and evaluating potential therapeutic molecules. This review addresses the production and regulation of O₂^•−, highlighting its biosynthesis, redox control, and its physiological and pathological roles in the development of inflammatory pain, as well as the pharmacological therapies under development aimed at its generation and/or action. Full article

Ischemia/reperfusion (I/R) injury following stroke results in increased neuronal cell death due to mitochondrial hyperactivity. Ischemia results in loss of regulatory phosphorylations on cytochrome c oxidase (COX) and cytochrome c of the electron transport chain (ETC), priming COX for hyperactivity. During reperfusion, the ETC operates at maximal speed, resulting in hyperpolarization of the mitochondrial membrane potential (ΔΨ_m) and reactive oxygen species (ROS) production. We have shown that COX-inhibitory near-infrared light (IRL) provides neuroprotection in small and large animal models of brain I/R injury. IRL therapy is non-invasive and non-pharmacological and does not rely on blood flow. We identified specific wavelengths of IRL, 750 and 950 nm, that inhibit COX activity. To model the mitochondrial effects following neuronal I/R, SH-SY5Y cells underwent oxygen–glucose deprivation/reoxygenation (OGD/R) ± IRL applied at the time of reoxygenation. Untreated cells exhibited ΔΨ_m hyperpolarization, whereas IRL treated cells showed no significant difference compared to control. IRL treatment suppressed ROS production, decreased the level of cell death, and reduced the time to normalize mitochondrial activity to baseline levels from 4–5 to 2.5 h of reperfusion time. We show that IRL treatment is protective by limiting ΔΨ_m hyperpolarization and ROS production, and by speeding up cellular recovery. Full article

Combined oxidative phosphorylation deficiency type 8 (COXPD8) is an autosomal recessive mitochondrial disorder caused by a mutation of the nuclear encoded mitochondrial alanyl-tRNA synthetase gene (AARS2). Clinical manifestations of COXPD8 include lethal infantile hypertrophic cardiomyopathy, pulmonary hypoplasia, generalized muscle weakness, and neurological involvement. We report a patient with COXPD8 caused by two mutations in the AARS2 gene. The c.1738 C>G mutation has not been previously reported, while the c.2872 C>T mutation has been associated with pulmonary hypoplasia and hypertrophic cardiomyopathy. Cardiac tissue, obtained through the LungMAP program, showed that, compared to other patients of similar ages, these two mutations affect not only the assembly of functional monomeric complexes (Cx) I and IV of the electron transport chain (ETC) but also limit the formation of respiratory supercomplexes. This patient had altered expression of some ETC proteins but normal expression of several enzymes of the tricarboxylic acid cycle. We also show that one of the control/comparison patients had an undiagnosed ETC Cx IV deficiency. In conclusion, our data demonstrate that the two mutations of the AARS2 gene are associated with failed assembly of Cx I and Cx IV and reduced formation of respiratory supercomplexes of the ETC, likely leading to acute bioenergetic stress. Full article

This study used NMR-based metabolomics to investigate the mode of action (MoA) of 6-hydroxydopamine (6-OHDA) toxicity in the SH-SY5Y neuroblastoma cell model. 6-OHDA, a structural analogue of dopamine, has been used to create a Parkinson’s disease model since 1968. Its selective uptake via catecholaminergic transporters leads to intracellular oxidative stress and mitochondrial dysfunction. SH-SY5Y cells were treated with 6-OHDA at its IC₅₀ concentration of 60 μM, and samples of treated and untreated groups were collected after 24 h. The endo metabolome was extracted using a methanol–water mixture, while the exo metabolome was represented by the culture media. Further, endo- and exo metabolomes of treated and untreated cells were analysed for metabolic changes. Our results demonstrated significantly high levels of glutathione, acetate, propionate, and NAD⁺, which are oxidative stress markers, enhanced due to ROS production in the system. In addition, alteration of myoinositol, taurine, and o-phosphocholine could be due to oxidative stress-induced membrane potential disturbance. Mitochondrial complex I inhibition causes electron transport chain (ETC) dysfunction. Changes in key metabolites of glycolysis and energy metabolism, such as glucose, pyruvate, lactate, creatine, creatine phosphate, glycine, and methionine, respectively, demonstrated ETC dysfunction. We also identified changes in amino acids such as glutamine, glutamate, and proline, followed by nucleotide metabolism such as uridine and uridine monophosphate levels, which were decreased in the treated group. 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

Toxoplasma gondii is an Apicomplexan parasite that possesses a well-developed system of scavengers of reactive oxygen species (ROS). Among its components, T. gondii mitochondrial superoxide dismutase (TgSOD2) is essential, as predicted by the CRISPR phenotype index and evidenced by the non-viability of its constitutive knockouts. As an obligate intracellular parasite, TgSOD2 is upregulated during extracellular stages. Herein, we generated a viable TgSOD2 knockdown mutant using an inducible auxin–degron system to explore the biological role of TgSOD2 in T. gondii. Depletion of TgSOD2 led to impaired parasite growth and replication, reduced mitochondrial membrane potential (MMP), abnormalities in the distribution of ATP synthase within its mitochondrial electron transport chain (mETC), and increased susceptibility to mETC inhibitors. Through a proximal biotinylation approach, we identified the interactions of TgSOD2 with complexes IV and V of its mETC, suggesting that these sites are sensitive to ROS. Our study provides the first insights into the role of TgSOD2 in maintaining its mitochondrial redox homeostasis and subsequent parasite replication fitness. Significance: Toxoplasma gondii infects nearly a third of the world population and can cause fetal miscarriages or life-threatening complications in vulnerable patients. Current therapies do not eradicate the parasite from the human hosts, rendering them at risk of recurrence during their lifetimes. T. gondii has a single mitochondrion, which is well-known for its susceptibility to oxidative damage that leads to T. gondii’s death. Therefore, targeting T. gondii mitochondrion remains an attractive therapeutic strategy for drug development. T. gondii’s mitochondrial superoxide dismutase is an antioxidant protein in the parasite mitochondrion and is essential for its survival. Understanding its biological role could reveal mitochondrial vulnerabilities in T. gondii and provide new leads for the development of effective treatments for T. gondii infections. Full article

ARID1A-deficient ovarian clear cell carcinoma is a highly lethal gynecologic cancer that depends heavily on mitochondrial respiration. Our biochemical and proteomic analyses reveal that ARID1A knockout cells exhibit marked upregulation of specific subunits within mitochondrial electron transport chain (ETC) Complexes I, III, and IV. However, this upregulation does not directly translate into increased sensitivity to broad-spectrum inhibitors targeting these complexes. These findings suggest that broad-spectrum mitochondrial inhibitors may not be effective therapeutic options for ARID1A-deficient cancers. Instead, the selective inhibition of specific ETC subunits may offer a more promising approach to exploit the metabolic vulnerabilities of ARID1A-deficient cells. Full article

Background: Reactive oxygen species (ROS) generated by mitochondrial dysfunction damage cellular organelles and contribute to skin aging. Therefore, strategies to reduce mitochondrial ROS production are considered important for alleviating skin aging, but no effective methods have been identified. Methods: In this study, we evaluated substances utilized as cosmetic ingredients and discovered Camellia sinensis (C. sinensis) as a substance that reduces mitochondrial ROS levels. Results: C. sinensis extracts were found to act as senolytics that selectively kill senescent fibroblasts containing dysfunctional mitochondria. In addition, C. sinensis extracts facilitated efficient electron transport in the mitochondrial electron transport chain (ETC) by increasing the efficiency of oxidative phosphorylation (OXPHOS), thereby reducing mitochondrial ROS production, a byproduct of the inefficient ETC. This novel mechanism of C. sinensis extracts led to the restoration of skin aging and the skin barrier. Furthermore, epigallocatechin gallate (EGCG) was identified as an active ingredient that plays a key role in C. sinensis extract-mediated skin aging recovery. Indeed, similar to C. sinensis extracts, EGCG reduced ROS and improved skin aging in an artificial skin model. Conclusions: Our data uncovered a novel mechanism by which C. sinensis extract reverses skin aging by reducing mitochondrial ROS production via selective senescent cell death/increased OXPHOS efficiency. Our results suggest that C. sinensis extract or EGCG may be used as a therapeutic agent to reverse skin aging in clinical and cosmetic applications. Full article

Increased acetylation or “hyperacetylation” of mitochondrial (MITO) proteins can lead to abnormalities of the electron transport chain (ETC) and oxidative phosphorylation. In this study we examined the levels of proteins that regulate acetylation. Studies were performed in isolated MITO fractions from left ventricular (LV) myocardium of seven healthy normal (NL) dogs and seven dogs with coronary microembolization-induced heart failure (HF, LV ejection fraction ~35%). Protein levels of drivers of hyperacetylation, namely sirtuin-3 (Sirt-3), a MITO deacetylase, and CD38, a regulator of nicotinamide adenine dinucleotide (NAD⁺), were measured by Western blotting, and the bands were quantified in densitometric units (du). To assess MITO function, MITO components directly influenced by a hyperacetylation state, namely the protein level of cytophillin-D (CyPD), a regulator of MITO permeability transition pore and MITO Complex-I activity, were also measured. Protein level of Sirt-3 and amount of NAD⁺ were decreased in HF compared to NL dogs. Protein levels of CD38 and CyPD were increased in HF compared to NL dogs. Complex-I activity was decreased in HF compared to NL dogs. The results support the existence of a protein hyperacetylation state in mitochondria of failing LV myocardium compared to NL. This abnormality can contribute to MITO dysfunction as evidenced by reduced Complex-I activity and opening of MITO permeability pores. Full article

For nearly three decades, interspecies somatic cell nuclear transfer (iSCNT) has been explored as a potential tool for cloning, regenerative medicine, and wildlife conservation. However, developmental inefficiencies remain a major challenge, largely due to persistent barriers in nucleocytoplasmic transport, mitonuclear communication, and epigenome crosstalk. This review synthesized peer-reviewed English articles from PubMed, Web of Science, and Scopus, spanning nearly three decades, using relevant keywords to explore the molecular mechanisms underlying iSCNT inefficiencies and potential improvement strategies. We highlight recent findings deepening the understanding of interspecies barriers in iSCNT, emphasizing their interconnected complexities, including the following: (1) nucleocytoplasmic incompatibility may disrupt nuclear pore complex (NPC) assembly and maturation, impairing the nuclear transport of essential transcription factors (TFs), embryonic genome activation (EGA), and nuclear reprogramming; (2) mitonuclear incompatibility could lead to nuclear and mitochondrial DNA (nDNA-mtDNA) mismatches, affecting electron transport chain (ETC) assembly, oxidative phosphorylation, and energy metabolism; (3) these interrelated incompatibilities can further influence epigenetic regulation, potentially leading to incomplete epigenetic reprogramming in iSCNT embryos. Addressing these challenges requires a multifaceted, species-specific approach that balances multiple incompatibilities rather than isolating a single factor. Gaining insight into the molecular interactions between the donor nucleus and recipient cytoplast, coupled with optimizing strategies tailored to specific pairings, could significantly enhance iSCNT efficiency, ultimately transforming experimental breakthroughs into real-world applications in reproductive biotechnology, regenerative medicine, and species conservation. Full article

HIV-associated neurocognitive disorders are prevalent despite antiretroviral intervention. Some HIV virotoxins, such as the trans-activator of transcription (Tat), are not targeted by antiretrovirals, and their neurotoxic actions may be exacerbated by opioids. Both Tat and morphine disrupt mitochondrial function, which may promote neurotoxicity, but the mechanisms are poorly understood. Herein, we assess the capacity of HIV Tat and morphine to alter the fundamental ability of mitochondria to generate and transfer energy along the electron transport chain (ETC). We find that exposure to Tat inhibits mitochondrial respiration driven by ETC complexes I or II in a concentration-dependent manner. Findings were consistent across models of permeabilized neuroblastoma cells, murine-derived mitoplasts, and mitochondria derived from mice exposed to Tat in vivo. In cell culture models, Tat promoted Ca²⁺ influx and the generation of cytosolic reactive oxygen species (ROS). Acute exposure to morphine exerted no effect on mitochondrial respiration, but morphine modestly offset Tat-mediated effects on complex I and some effects for the generation of ROS. Morphine did not exert any protective effects when acutely administered in vivo. The mitoprotective steroid, allopregnanolone (AlloP), increased mitochondrial respiration in neuroblastoma cells (complex I) or mitoplasts (complex II) and attenuated Tat-mediated impairment of complexes I and II in neuroblastoma cells or mice exposed to Tat in vivo. AlloP further attenuated Tat-mediated intracellular Ca²⁺ influx and cytosolic ROS production. Taken together, these results suggest that HIV Tat compromises mitochondrial function through the impairment of respiratory complexes I and II and that physiological AlloP may exert protective effects. Full article

Triple-negative breast cancer (TNBC) presents a significant therapeutic challenge due to the absence of specific targeted treatments. In this study, we explored the therapeutic potential of xanthocillin X dimethyl ether (XanDME), a naturally occurring isocyanide isolated from the marine fungus Scedosporium apiospermum, on TNBC. To elucidate the underlying mechanism, we initially demonstrated that XanDME directly binds to hemin, the oxidized form of heme, in vitro, corroborating previous reports. This interaction led to the depletion of intracellular regulatory heme. We further established that XanDME translocates into the mitochondria, where it interacts with crucial hemoproteins, namely cytochromes. The binding of XanDME with mitochondrial cytochromes disrupts the electron transport chain (ETC), inhibits the activity of mitochondrial complexes, and inactivates mitochondrial respiration. The inhibitory activity of XanDME on mitochondrial function significantly contributes to its anti-TNBC effects, as observed both in vitro and in vivo. Our study underscores the potential of XanDME against TNBC, warranting further investigations. Full article

This review discusses the literature data on the synthesis, physicochemical properties, and cytotoxicity of composite nanoparticles bearing the mitochondrial protein cytochrome c (cytC), which can act as a proapoptotic mediator in addition to its main function as an electron carrier in the electron transport chain. The introduction of exogenous cytC via absorption of carrier particles, the phagocytosis of colloid particles of submicrometric size, or the receptor-mediated endocytosis of nanoparticles in cancer cells, initiates the process of apoptosis—a multistage cascade of biochemical reactions leading to complete destruction of the cells. CytC–carrier composite particles have the potential for use in the treatment of neoplasms with superficial localization: skin, mouth, stomach, colon, etc. This approach can solve the two main problems of anticancer therapy: selectivity and non-toxicity. Selectivity is based on the incapability of the normal cell to absorb (nano)particles, except for the cells of the immune system. The use of cytC as a protein that normally functions in mitochondria is harmless for the macroorganism. In this review, the factors limiting cytotoxicity and the ways to increase it are discussed from the point of view of the physicochemical properties of the cytC–carrier particles. The different techniques used for the preparation of cytC-bearing colloids and nanoparticles are discussed. Articles reporting the achievement of high cytotoxicity with each of the techniques are critically analyzed. Full article