Search Results (52)

The single-electron reduction of redox-active drugs and xenobiotics (quinones, aromatic nitrocompounds, and N-oxides) by flavoenzymes, which initiates redox cycling and oxidative stress, is an important factor in their therapeutic/toxic effects. This review summarizes information on the action of mitochondrial flavoenzymes from various organisms in these processes, emphasizing the kinetic and mechanistic aspects. The flavoenzymes discussed also include those of which only a fraction is localized in mitochondria. According to kinetic data, the most effective generator of free radicals of xenobiotics is respiratory Complex I. However, it is unclear to what extent these reactions can compete with the rapid reduction of ubiquinone in normally functioning mitochondria. In specific cases, a very active free radical generator can be the NADPH:adrenodoxin reductase–adrenodoxin complex. The properties of other dehydrogenases–electrontransferases (succinate:ubiquinone reductase, fatty acid oxidation system) are less well characterized. Due to its high catalytic capacity, a potential but poorly studied source of free radicals of xenobiotics may be NADH:cytochrome b₅ reductase and its complex with cytochrome b₅. Flavoenzyme disulfide reductases, with the possible exception of Plasmodium falciparum thioredoxin reductase, are less active free radical generators. Importantly, in most cases, flavoenzymes perform the mixed single- and two-electron reduction of xenobiotics. According to the available data, the reactivity of redox cyclers depends mostly on their standard single-electron reduction potential and is little influenced by their structure. Therefore, in order to intensify these processes or achieve some structural specificity, it is necessary to focus on the selective accumulation of compounds in mitochondria. Full article

Amino acids are key regulators of metabolism, their coordinated effects on skeletal muscle signaling and metabolic remodeling under physiological conditions remain incompletely understood. Here, we investigated whether 14 weeks of combined histidine and proline supplementation (HISPRO; 700 mg/kg) enhances skeletal muscle function through metabolic reprogramming in normal ICR mice. HISPRO significantly improved muscle performance compared with the control group, including grip strength, rota-rod, and treadmill. Histological and biochemical analyses revealed a shift toward oxidative muscle phenotype compared with the control group, with larger muscle fibers and succinate dehydrogenase-positive fibers. Consistently, HISPRO promoted mitochondrial biogenesis and oxidative metabolism compared with the control group, as evidenced by upregulation of mitochondrial regulatory genes, mitochondrial DNA copy number, citrate synthase activity, and oxidative phosphorylation (OXPHOS) complex levels in skeletal muscles. Mechanistically, HISPRO was associated with activation of the SIRT1-PGC1α-AMPK signaling axis compared with the control group, as evidenced by increased Nampt and Nmnat1 expression, an elevated NAD⁺/NADH ratio, and enhanced AMPK phosphorylation. SIRT1 inhibition markedly attenuated HISPRO-induced increases in mitochondrial biogenesis markers but did not fully suppress OXPHOS protein expression, suggesting the involvement of both SIRT1-dependent and -independent mechanisms. Notably, HISPRO also improved muscle function in dexamethasone-induced muscle atrophy model. It restored mitochondrial biogenesis and function, and suppressed atrophy-related markers compared with the dexamethasone-treated group. HISPRO may contribute to improving muscle quality through coordinated metabolic regulation and could represent a complementary nutritional for supporting muscle metabolic health. Full article

Brucellosis, acting as a typical chronic zoonotic disease, is caused by the invasion of Brucella into the human body. Outer membrane protein 25 (Omp25), specifically localized on the Brucella membrane, is the main virulence factor of Brucella and participates in multiple links of the damage process. Omp25c, a porin protein of Brucella, is a paralog of Omp25 with high sequence identity. NADH dehydrogenase [ubiquinone] complex I assembly factor 2 (Ndufaf2) has a key function in cell energy metabolism, particularly in the formation and activity of the mitochondrial respiratory chain. Loss of Ndufaf2 results in oxidative stress and mitochondrial DNA (mtDNA) deletion. However, the functional relationship between Omp25c and Ndufaf2, the underlying mechanism of the proteins, remains unclear. In this work, we purified the Omp25c and Ndufaf2proteins. Our data revealed that Omp25c directly interacts with Ndufaf2, as determined using Biacore analysis. In addition, assays revealed that Ompa2c reshapes the host cell’s redox environment by decreasing the oxidized nicotinamide adenine dinucleotide/reduced nicotinamide adenine dinucleotide (NAD⁺/NADH) ratioand adenosine triphosphate (ATP) production, whereas Ndufaf2 exerts an opposing regulatory effect; Co-expression results further revealed an antagonistic relationship between the two during metabolic processes. These findings provide a new perspective for elucidating the mechanisms of mitochondrial functional regulation in Brucella–host interactions and lay the theoretical and experimental foundation for drug development targeting metabolic interventions to eliminate intracellular pathogens. Full article

Cystic echinococcosis (CE) is caused by a tapeworm of the Echinococcus granulosus s.l. species complex belonging to the Taeniidae family. CE affects more than 100 countries, including Poland, while remaining a significant public health threat to both humans and livestock. The aim of this study was to identify the genotypes responsible for cases of cystic echinococcosis in Poland by conducting molecular analysis of larvae isolated from Polish patients, and to investigate the diagnostic pathways leading to CE diagnosis. Between April 2023 and January 2025, tissue samples were collected from 10 patients following hepatectomy. Analysis of diagnostic pathways revealed that radiological findings followed by PCR or histopathological testing were sufficient to establish a reliable diagnosis of CE in 90% and 100% of cases, respectively. Serological tests showed lower sensitivity, reaching 86% for ELISA and 71% for Western blot. DNA extracted from all samples was used as the template in PCR to amplify and sequence the region of the mitochondrial NADH dehydrogenase 1 gene (nad1). PCR analysis confirmed presence of Echinococcus granulosus s.l. species in eight cases. All obtained nad1 sequences showed identity with the Echinococcus canadensis G7 (pig) strain. These results indicate that it remains the most frequent causative agent of human cystic echinococcosis in Poland. Full article

Corydalis impatiens (Papaveraceae) is a traditional Tibetan medicinal plant (“Pa Xia Ga”) whose mitochondrial genome evolution remains unexplored, particularly in the context of high-altitude adaptation. This study presents the first complete mitochondrial genome sequence of an alpine Corydalis species to establish a comparative framework with the lowland congener C. pauciovulata for investigating environment-associated mitochondrial evolution. Using Illumina sequencing and reference-guided assembly, we characterized a 688,959 bp circular genome containing 74 genes, with GC content variations reflecting functional compartmentalization—elevated in structural RNA genes (tRNAs: 51.24%; rRNAs: 52.79%) versus protein-coding genes (44.19%). We identified 719 RNA editing sites concentrated in NADH dehydrogenase genes, suggesting post-transcriptional optimization of respiratory complex I under hypoxic conditions. The genome harbors 50 dispersed repeats (7.50%) and 67 SSRs with A-rich predominance, providing species-specific markers for authenticating “Pa Xia Ga” in Tibetan medicine quality control. Phylogenomic analysis confirms close affinity with C. pauciovulata while resolving intrageneral relationships within Ranunculales. These findings establish a dual-reference system for distinguishing conserved genus-level features from altitude-associated adaptations, enabling future comparative mitogenomics across the 465-species genus and supporting DNA-based medicinal plant identification. Full article

Background/Objectives: We have previously demonstrated that fatty acid oxidation (FAO) enzymes physically and functionally interact with electron transfer chain supercomplexes (ETC-SC) at two contact points. The FAO trifunctional protein (TFP) and electron transfer flavoprotein dehydrogenase (ETFDH) interact with the NADH⁺-binding domain of ETC complex I (com I) and the core 2 subunit of complex III (com III), respectively. In addition, the FAO enzyme very-long-chain acyl-CoA dehydrogenase (VLCAD) interacts with TFP. These interactions define a functional FAO-ETC macromolecular complex (FAO-ETC MEC) in which FAO-generated NADH⁺ and FADH₂ can safely transfer electron equivalents to ETC in order to generate ATP. Methods: In this study, we use multiple mitochondrial functional studies to demonstrate the effect of added VLCAD protein on mutant mitochondria. Results: We demonstrate that heart mitochondria from a VLCAD knockout (KO) mouse exhibit disrupted supercomplexes, with significantly reduced levels of TFPα and TFPβ subunits, electron transfer flavoprotein a-subunit (ETFα), and NDUFV2 subunit of com I in the FAO-ETC MEC. In addition, the activities of individual oxidative phosphorylation (OXPHOS) enzymes are decreased, as is the transfer of reducing equivalents from palmitoyl-CoA to ETC (FAO-ETC flux). However, the total amount of these proteins did not decrease in VLCAD KO animals. These results suggest that loss of VLCAD affects the interactions of FAO and ETC proteins in the FAO-ETC MEC. Reconstitution of VLCAD-deficient heart mitochondria with recombinant VLCAD improved the levels of FAO-ETC MEC proteins and enzyme activities, as well as restoring FAO-ETC flux. It also reduced mitochondrial ROS levels, previously demonstrated to be elevated in VLCAD-deficient mitochondria. In contrast, incubation of VLCAD KO mitochondria with two VLCADs with mutations in the C-terminal domain of the enzyme (A450P and L462P) did not restore FAO-ETC MECs. Conclusions: These results suggest that VLCAD is a necessary component of the FAO-ETC MEC and plays a major role in assembly of the macro-supercomplex. These studies provide evidence that both the level of enzyme and its structural confirmation are necessary to stabilize the FAO-ETC MEC. 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

As distant hybridization has profound implications for evolutionary biology, aquaculture, and biodiversity conservation, this study aims to elucidate patterns of maternal inheritance, genetic divergence, and phylogenetic relationships by synthesizing mitochondrial genome (mitogenome) data from 74 distant hybrid fish species. These hybrids span diverse taxa, including 48 freshwater and 26 marine species, with a focus on Cyprinidae (n = 35) and Epinephelus (n = 14), representing the most frequently hybridized groups in freshwater and marine systems, respectively. Mitogenome lengths were highly conserved (15,973 to 17,114 bp); however, the genetic distances between hybrids and maternal species varied from 0.001 to 0.17, with 19 hybrids (25.7%) showing distances >0.02. Variable sites in these hybrids were randomly distributed but enriched in hypervariable regions, such as the D-loop and NADH dehydrogenase subunits 1, 3 and 6 (ND2, ND3, and ND6) genes, likely reflecting maternal inheritance (reported in Cyprinus carpio × Carassius auratus). Moreover, these genes were under purifying selection pressure, revealing their conserved nature. Phylogenetic reconstruction using complete mitogenomes revealed three distinct clades in hybrids: (1) Acipenseriformes, (2) a freshwater cluster dominated by Cypriniformes and Siluriformes, and (3) a marine cluster comprising Centrarchiformes, Pleuronectiformes, Scombriformes, Cichliformes, Anabantiformes, Tetraodontiformes, Perciformes, and Salmoniformes. The prevalence of Cyprinidae hybrids underscores their importance in aquaculture for hybridization, where traits such as rapid growth and disease resistance are enhanced. In contrast, marine hybrids are valued for their market value and adaptability. While mitogenome data robustly support maternal inheritance in most cases, exceptions suggest complex mechanisms, such as doubly uniparental inheritance (DUI), in distantly related crosses. Moreover, AT-skew of genes in hybrids revealed a paternal leakage of traits in mitogenomes. This study also highlights ecological risks, such as genetic swamping in native populations, emphasizing the need for responsible hybridization practices. These findings advance our understanding of the role of hybridization in fish evolution and aquaculture, providing a genomic framework and policy recommendations for optimizing breeding programs, hybrid introduction, and mitigating conservation challenges. Full article

Background: Parkinson’s disease (PD) is a progressive neurodegenerative disorder linked to oxidative stress, mitochondrial dysfunction, and neuroinflammation. This study evaluates the neurofunctional and immunomodulatory effects of an aqueous extract combining cocoa seed husk and guarana powder (GuaCa). Eighteen extracts were characterized by flavonoid and polyphenol content, antioxidant activity, and genoprotective potential. The HCE3 extract, rich in catechins, quercetin, and epigallocatechin gallate, was selected for further analysis in three models: Eisenia fetida earthworms, SH-SY5Y neuron-like cells, and peripheral blood mononuclear cells (PBMCs) from PD patients. Results: The extracts showed antioxidant and genoprotective activity and contained flavonoid. No significant toxicity was observed in Eisenia fetida. In SH-SY5Y cells, GuaCa increased cell viability and brain-derived neurotrophic factor (BDNF) levels and reduced mitochondrial damage by lowering extracellular NDUSF7 (subunit of the NADH dehydrogenase (ubiquinone) complex) levels. In dPD-PBMCs cultures, GuaCa reduced pro-inflammatory cytokine IL-6 levels, indicating immunomodulatory effects. Conclusion: GuaCa shows promise as a nutraceutical for managing neuroinflammation and mitochondrial dysfunction in PD. Further clinical studies are needed to confirm GuaCa extract efficacy and potential for neuroprotective dietary strategies. Full article

Background/Objectives: Mitochondria are the main organelles for ATP synthesis able to produce energy for several different cellular activities. Cardiac cells require high amounts of energy and, thus, they contain a high number of mitochondria. Consequently, mitochondrial dysfunction in these cells is a crucial factor for the development of cardiovascular diseases. Mitochondria constitute central regulators of cellular metabolism and energy production, producing approximately 90% of the cells’ energy needs in the form of ATP via oxidative phosphorylation. The mitochondria have their own circular, double-stranded DNA encoding 37 genes. Any mitochondrial DNA sequence anomaly may result in defective oxidative phosphorylation and lead to cardiac dysfunction. Methods: In this study, we investigated the potential association between mitochondrial DNA mutation and cardiovascular disease. Cardiac tissue and serum samples were collected from seven patients undergoing coronary artery bypass grafting. Total DNA was extracted from cardiac muscle tissue specimens and serum and each sample was subjected to polymerase chain reaction (PCR) to amplify the NADH dehydrogenase 1 (ND1) gene, which is part of the mitochondrial complex I enzyme complex and was screened for mutations. Results: We identified one patient with a homoplasmic A to G substitution mutation in cardiac tissue DNA and two patients with heteroplasmic A3397G mutation in serum DNA. Specifically, amplicon sequence analysis revealed a homoplasmic A3397G substitution in the ND1 gene in a tissue sample of the patient with ID number 1 and a heteroplasmic mutation in A3397G in serum samples of patients with ID numbers 3 and 6, respectively. The A to G substitution changes the amino acid from methionine (ATA) to valine (GTA) at position 31 of the ND1 gene. Conclusions: The detection of this novel mutation in patients with coronary artery disease may contribute to our understanding of the association between mitochondrial dysfunction and the disease, implying that mitochondria may be key players in the pathogenesis of cardiovascular diseases. Full article

The respiratory activities of mitochondrial complexes I, II, and IV were analyzed in permeabilized Rhodotorula mucilaginosa cells and isolated mitochondria, and the kinetic parameters K_0.5 and V_max were obtained. No difference in substrate affinities were found between mitochondria and permeabilized cells. The activities of the components of the mitochondrial respiratory chain of the Antarctic yeast R. mucilaginosa M94C9 were identified by in-gel activity and SDS-PAGE. The mitochondria exhibited activity for the classical components of the electron transport chain (Complexes I, II, III, and IV), and supercomplexes were formed by a combination of the respiratory complexes I, III, and IV. Unfortunately, the activities of the monomeric and dimeric forms of the F1F0-ATP synthase were not revealed by the in-gel assay, but the two forms of the ATP synthase were visualized in the SDS-PAGE. Furthermore, two alternative pathways for the oxidation of cytosolic NADH were identified: the alternative NADH dehydrogenase and the glycerol-3-phosphate dehydrogenase. In addition, an NADPH dehydrogenase and a lactate cytochrome b2 dehydrogenase were found. The residual respiratory activity following cyanide addition suggests the presence of an alternative oxidase in cells. Full article

Gallium-based therapy has been considered a potentially effective cancer therapy for decades and has recently re-emerged as a novel therapeutic strategy for the management of glioblastoma tumors. Gallium targets the iron-dependent phenotype associated with aggressive tumors by mimicking iron in circulation and gaining intracellular access through transferrin-receptor-mediated endocytosis. Mechanistically, it is believed that gallium inhibits critical iron-dependent enzymes like ribonucleotide reductase and NADH dehydrogenase (electron transport chain complex I) by replacing iron and removing the ability to transfer electrons through the protein secondary structure. However, information regarding the effects of gallium on cellular iron metabolism is limited. As mitochondrial iron metabolism serves as a central hub of the iron metabolic network, the goal of this study was to investigate the effects of gallium on mitochondrial iron metabolism in glioblastoma cells. Here, it has been discovered that gallium nitrate can induce mitochondrial iron depletion, which is associated with the induction of DNA damage. Moreover, the generation of gallium-resistant cell lines reveals a highly unstable phenotype characterized by impaired colony formation associated with a significant decrease in mitochondrial iron content and loss of the mitochondrial iron uptake transporter, mitoferrin-1. Moreover, gallium-resistant cell lines are significantly more sensitive to radiation and have an impaired ability to repair any sublethal damage and to survive potentially lethal radiation damage when left for 24 h following radiation. These results support the hypothesis that gallium can disrupt mitochondrial iron metabolism and serve as a potential radiosensitizer. Full article

The mitochondrial electron transport chain (mETC) contains molecular targets of volatile general anesthetics (VGAs), which places individuals with mETC mutations at risk for anesthetic complications, as exemplified by patients with Leigh syndrome (LS). The Drosophila melanogaster homozygous mutant for ND-23, which encodes a subunit of mETC Complex I, replicates numerous characteristics of LS, including neurodegeneration, shortened lifespan, behavioral anesthetic hypersensitivity, and toxicity. The anesthetic phenotype of toxicity (lethality) is also observed in flies homozygous for mutations in other Complex I subunits. By contrast, mutations conferring sensitivity have not yet been identified for subunits of Complexes II–V. Furthermore, anesthetic phenotypes are thought to be recessive; that is, risk is not conferred by heterozygous mutations. However, at older ages, exposure of heterozygous mutant ND-23 flies to the VGA isoflurane in 75% oxygen (hyperoxia) results in toxicity. It is also unknown whether combinations of heterozygous mutations in different subunits of the mETC can result in anesthetic toxicity. Here, we show that, following exposure to isoflurane in hyperoxia, flies carrying heterozygous mutations in two Complex I subunits, ND-23 and ND-SGDH (NADH dehydrogenase (ubiquinone) SGDH subunit), had a level of anesthetic toxicity that exceeded the added toxicities of the individual heterozygous mutations. In addition, we show that flies heterozygous for two different alleles of the Complex II gene SdhB were susceptible to isoflurane/hyperoxia-induced anesthetic toxicity. Finally, a mutation in the SdhC subunit of Complex II of Caenorhabditis elegans resulted in isoflurane-induced mortality, supporting the role of Complex II in anesthetic toxicity. These data expand the landscape of mutations in the mETC that increase sensitivity to anesthetic toxicity. Full article

It is well known that in the heart and kidney mitochondria, more than 95% of ATP production is supported by the β-oxidation of long-chain fatty acids. However, the β-oxidation of fatty acids by mitochondria has been studied much less than the substrates formed during the catabolism of carbohydrates and amino acids. In the last few decades, several discoveries have been made that are directly related to fatty acid oxidation. In this review, we made an attempt to re-evaluate the β-oxidation of long-chain fatty acids from the perspectives of new discoveries. The single set of electron transporters of the cardiac mitochondrial respiratory chain is organized into three supercomplexes. Two of them contain complex I, a dimer of complex III, and two dimers of complex IV. The third, smaller supercomplex contains a dimer of complex III and two dimers of complex IV. We also considered other important discoveries. First, the enzymes of the β-oxidation of fatty acids are physically associated with the respirasome. Second, the β-oxidation of fatty acids creates the highest level of QH₂ and reverses the flow of electrons from QH₂ through complex II, reducing fumarate to succinate. Third, β-oxidation is greatly stimulated in the presence of succinate. We argue that the respirasome is uniquely adapted for the β-oxidation of fatty acids. The acyl-CoA dehydrogenase complex reduces the membrane’s pool of ubiquinone to QH₂, which is instantly oxidized by the smaller supercomplex, generating a high energization of mitochondria and reversing the electron flow through complex II, which reverses the electron flow through complex I, increasing the NADH/NAD⁺ ratio in the matrix. The mitochondrial nicotinamide nucleotide transhydrogenase catalyzes a hydride (H^-, a proton plus two electrons) transfer across the inner mitochondrial membrane, reducing the cytosolic pool of NADP(H), thus providing the heart with ATP for muscle contraction and energy and reducing equivalents for the housekeeping processes. Full article

Previous studies conducted in our lab revealed microbial assemblages to vary significantly between high (ARS-FY-H) and low fillet yield (ARS-FY-L) genetic lines in adult rainbow trout. We hypothesized that a high ARS-FY-H donor microbiome can accelerate somatic growth in microbiome-depleted rainbow trout larvae of the ARS-FY-L line. Germ-depleted larvae of low ARS-FY-L line trout reared in sterile environments were exposed to high- or low-fillet yield-derived microbiomes starting at first feeding for 27 weeks. Despite weight-normalized diets, somatic mass was significantly increased in larvae receiving high fillet yield microbiome cocktails at 27 weeks post-hatch. RNA-seq from fish tails reveals enrichment in NADH dehydrogenase activity, oxygen carrier, hemoglobin complex, gas transport, and respiratory pathways in high fillet yield recolonized larvae. Transcriptome interrogation suggests a relationship between electron transport chain inputs and body weight assimilation, mediated by the gut microbiome. These findings suggest that microbiome payload originating from high fillet yield adult donors primarily accelerates juvenile somatic mass assimilation through respiratory and mitochondrial input modulation. Further microbiome studies are warranted to assess how increasing beneficial microbial taxa could be a basis for formulating appropriate pre-, pro-, or post-biotics in the form of feed additives and lead to fecal transplantation protocols for accelerated feed conversion and fillet yield in aquaculture. Full article