Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.9.3.1 (cytochrome oxidase)
8,822 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The mitochondrion is an important cellular component responsible for regulating energy, oxidative metabolism, and acclimatization to high altitude. This study is aimed at investigating the impact of long-term exposure to hypoxia on the amount of mitochondrial DNA (mtDNA) in rat livers. Male Sprague-Dawley rats were randomized and exposed to normoxia (group I), or 5,000 m (barometric pressure about 405.35 mmHg) above the sea level (a hypoxic condition) for 23 and 1 h normoxia daily for five consecutive days (group II), 15 days (group III), and 30 days (group IV), respectively. The levels of plasma malondialdehyde (MDA), homocysteine (Hcy), superoxide dismutase (SOD), and alanine aminotransferase (ALT), the contents of liver mtDNA, mitochondrial transcription factor A (mtTFA), cytochrome oxidase 1 (COX1), COX2, and COX3 mRNA transcripts, and mitochondrial respiratory activity were examined immediately after the last cycle. In comparison with that in control rats, 5-15 cycles of hypoxia/normoxia significantly increased the levels of plasma MDA and ALT, but reduced the levels of Hcy and SOD, accompanied by impairing liver respiratory function in rats. Long-term (30) cycles of hypoxia/normoxia reduced the levels of plasma MDA and ALT, but increased the levels of SOD and Hcy, accompanied by decreased mtTFA expression and mtDNA amount, improved mitochondrial respiratory function in rat liver, when compared that of 5-15 cycles of hypoxia/normoxia. Our data indicate that long-term cycles of hypoxia/normoxia increases the amount of mtDNA and up-regulates COX expression, contributing to acclimatization to very high altitude in rats.
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PMID:Long-term cycles of hypoxia and normoxia increase the contents of liver mitochondrial DNA in rats. 2266 Oct 54

Mitochondria are involved in the regulation of cell differentiation processes, but its function changes and molecular mechanisms are not yet clear. In this study, we found that mitochondrial functions changed obviously when K562 cells were induced to megakaryocytic differentiation by phorbol 12-myristate 13-acetate (PMA). During the cell differentiation, the reactive oxygen species (ROS) level was increased, mitochondrial membrane potential declined and respiratory chain complex IV activity was decreased. Treatment with specific inhibitor of mitochondrial respiratory chain complex IV led to a significant inhibition in mitochondrial membrane potential and reduction of PMA-induced cell differentiation. However, treatment with cyclosporine A, a stabilization reagent of mitochondrial membrane potential, did not improve the down-regulation of mitochondrial respiratory chain complex IV induced by PMA. Furthermore, we found that the level of the complex IV core subunit COX3 and mitochondrial transport-related proteins Tim9 and Tim10 were decreased during the differentiation of K562 cells induced by PMA, suggesting an important role of these factors in mitochondrial functional changes. Our results suggest that changes in mitochondrial functions are involved in the PMA-induced K562 cell differentiation process, and the maintenance of the steady-state of mitochondrial functions plays a critical role in the regulation of cell differentiation.
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PMID:Megakaryocytic differentiation of K562 cells induced by PMA reduced the activity of respiratory chain complex IV. 2481 82

Given the coevolution process occurring between nuclear and mitochondrial genomes, the effects of introgressive hybridization remain puzzling. In this study, we take advantage of the natural co-occurrence of two biotypes bearing a similar nuclear genome (Chrosomus eos) but harbouring mitochondria from different species (wild type: C. eos; cybrids: Chrosomus neogaeus) to determine the extent of phenotype changes linked to divergence in the mitochondrial genome. Changes were assessed through differences in gene expression, enzymatic activity, proteomic and swimming activity. Our data demonstrate that complex IV activity was significantly higher in cybrids compared to wild type. This difference could result from one variable amino acid on the COX3 mitochondrial subunit and/or from a tremendous change in the proteome. We also show that cybrids present a higher swimming performance than wild type. Ultimately, our results demonstrate that the absence of coevolution for a period of almost ten million years between nuclear and mitochondrial genomes does not appear to be necessarily deleterious but could even have beneficial effects. Indeed, the capture of foreign mitochondria could be an efficient way to circumvent the selection process of genomic coevolution, allowing the rapid accumulation of new mutations in C. eos cybrids.
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PMID:Interactions between nuclear genes and a foreign mitochondrial genome in the redbelly dace Chrosomus eos. 2627 40

In the present study, we determined the complete mitochondrial genome of Huananpotamon lichuanense (Decapoda: Brachyura) for the first time. The genome is 15,380bp in length and typically consists of 37 genes. When the gene order was compared to the ancestral crustacean type, two tRNA genes (tRNA^His and tRNA^Gln) were rearranged in H. lichuanense, and the translocation of tRNA^Gln appeared only in Potamoidea crabs, such as Geothelphusa dehaani and Sinopotamon xiushuiense, supporting the monophyly of the Potamoidea superfamily. Thirteen protein-coding genes and 2 rRNA genes were divided into five complexes to perform the phylogenetic analysis, and the results showed that the trees constructed by complex I (ND1-ND6 and ND4L), complex IV (COX1-COX3) and rRNA genes better accord with the morphological classification system, suggesting that molecular markers of higher-level phylogeny can be developed in these three complexes in the future. The estimated divergence time for freshwater crabs is approximately 133.58Ma, and G. dehaani from Japan diverged from the freshwater crabs of mainland China approximately 60.66Ma. A selective pressure analysis based on current data revealed obviously increasing dN/dS ratios (except for ATP6 and ND4L) of freshwater crabs, and the accumulation of nonsynonymous mutations suggests that terrestrial habitats provide a relatively relaxed selective pressure environment for this group.
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PMID:The complete mitochondrial genome of Huananpotamon lichuanense (Decapoda: Brachyura) with phylogenetic implications for freshwater crabs. 2930 51

Assembly factors play a critical role in the biogenesis of mitochondrial respiratory chain complexes I-IV where they assist in the membrane insertion of subunits, attachment of co-factors, and stabilization of assembly intermediates. The major fraction of complexes I, III and IV are present together in large molecular structures known as respiratory chain supercomplexes. Several assembly factors have been proposed as required for supercomplex assembly, including the hypoxia inducible gene 1 domain family member HIGD2A. Using gene-edited human cell lines and extensive steady state, translation and affinity enrichment proteomics techniques we show that loss of HIGD2A leads to defects in the de novo biogenesis of mtDNA-encoded COX3, subsequent accumulation of complex IV intermediates and turnover of COX3 partner proteins. Deletion of HIGD2A also leads to defective complex IV activity. The impact of HIGD2A loss on complex IV was not altered by growth under hypoxic conditions, consistent with its role being in basal complex IV assembly. Although in the absence of HIGD2A we show that mitochondria do contain an altered supercomplex assembly, we demonstrate it to harbor a crippled complex IV lacking COX3. Our results redefine HIGD2A as a classical assembly factor required for building the COX3 module of complex IV.
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PMID:HIGD2A is Required for Assembly of the COX3 Module of Human Mitochondrial Complex IV. 3231 97

The mitochondrial respiratory chain enzymes are organized as individual complexes and supercomplexes, whose biogenesis remains to be fully understood. To disclose the role of the human Hypoxia Inducible Gene Domain family proteins HIGD1A and HIGD2A in these processes, we generate and characterize HIGD-knockout (KO) cell lines. We show that HIGD2A controls and coordinates the modular assembly of isolated and supercomplexed complex IV (CIV) by acting on the COX3 assembly module. In contrast, HIGD1A regulates CIII and CIII-containing supercomplex biogenesis by supporting the incorporation of UQCRFS1. HIGD1A also clusters with COX4-1 and COX5A CIV subunits and, when overexpressed, suppresses the CIV biogenesis defect of HIGD2A-KO cells. We conclude that HIGD1A and HIGD2A have both independent and overlapping functions in the biogenesis of respiratory complexes and supercomplexes. Our data illuminate the existence of multiple pathways to assemble these structures by dynamic HIGD-mediated CIV biogenesis, potentially to adapt to changing environmental and nutritional conditions.
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PMID:Distinct Roles of Mitochondrial HIGD1A and HIGD2A in Respiratory Complex and Supercomplex Biogenesis. 3237 44


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