bims-cytox1 Biomed News
on Cytochrome oxidase subunit 1
Issue of 2021‒12‒19
three papers selected by
Gavin McStay
Staffordshire University

  1. Sci Rep. 2021 Dec 13. 11(1): 23909
      Mitochondrial diseases are a group of heterogeneous genetic metabolic diseases caused by mitochondrial DNA (mtDNA) or nuclear DNA (nDNA) gene mutations. Mining the gene-disease association of mitochondrial diseases is helpful for understanding the pathogenesis of mitochondrial diseases, for carrying out early clinical diagnosis for related diseases, and for formulating better treatment strategies for mitochondrial diseases. This project researched the relationship between genes and mitochondrial diseases, combined the Malacards, Genecards, and MITOMAP disease databases to mine the knowledge on mitochondrial diseases and genes, used database integration and the sequencing method of the phenolyzer tool to integrate disease-related genes from different databases, and sorted the disease-related candidate genes. Finally, we screened 531 mitochondrial related diseases, extracted 26,723 genes directly or indirectly related to mitochondria, collected 24,602 variant sites on 1474 genes, and established a mitochondrial disease knowledge base (MitDisease) with a core of genes, diseases, and variants. This knowledge base is helpful for clinicians who want to combine the results of gene testing for diagnosis, to understand the occurrence and development of mitochondrial diseases, and to develop corresponding treatment methods.
  2. FASEB J. 2022 Jan;36(1): e22091
      Hepatoencephalopathy due to combined oxidative phosphorylation deficiency type 1 (COXPD1) is a recessive mitochondrial translation disorder caused by mutations in GFM1, a nuclear gene encoding mitochondrial elongation factor G1 (EFG1). Patients with COXPD1 typically present hepatoencephalopathy early after birth with rapid disease progression, and usually die within the first few weeks or years of life. We have generated two different mouse models: a Gfm1 knock-in (KI) harboring the p.R671C missense mutation, found in at least 10 patients who survived more than 1 year, and a Gfm1 knock-out (KO) model. Homozygous KO mice (Gfm1-/- ) were embryonically lethal, whereas homozygous KI (Gfm1R671C / R671C ) mice were viable and showed normal growth. R671C mutation in Gfm1 caused drastic reductions in the mitochondrial EFG1 protein content in different organs. Six- to eight-week-old Gfm1R671C / R671C mice showed partial reductions of in organello mitochondrial translation and respiratory complex IV enzyme activity in the liver. Compound heterozygous Gfm1R671C /- showed a more pronounced decrease of EFG1 protein in liver and brain mitochondria, as compared with Gfm1R671C / R671C mice. At 8 weeks of age, their mitochondrial translation rates were significantly reduced in both tissues. Additionally, Gfm1R671C /- mice showed combined oxidative phosphorylation deficiency (reduced complex I and IV enzyme activities in liver and brain), and blue native polyacrylamide gel electrophoresis analysis revealed lower amounts of both affected complexes. We conclude that the compound heterozygous Gfm1R671C /- mouse presents a clear dysfunctional molecular phenotype, showing impaired mitochondrial translation and combined respiratory chain dysfunction, making it a suitable animal model for the study of COXPD1.
    Keywords:   Gfm1 ; COXPD1; animal model; elongation factor G1; mitochondria; translation
  3. PLoS One. 2021 ;16(12): e0261465
      Mitochondria are sites of cellular respiration, which is accompanied by the generation of dangerous reactive oxygen species (ROS). Cells have multiple mechanisms to mitigate the dangers of ROS. Here we investigate the involvement of the COX complex assembly chaperone COX11 (cytochrome c oxidase 11) in cellular redox homeostasis, using homologs from the flowering plant Arabidopsis thaliana (AtCOX11) and yeast Saccharomyces cerevisiae (ScCOX11). We found that AtCOX11 is upregulated in Arabidopsis seedlings in response to various oxidative stresses, suggesting a defensive role. In line with this, the overexpression of either AtCOX11 or ScCOX11 reduced ROS levels in yeast cells exposed to the oxidative stressor paraquat. Under normal growth conditions, both Arabidopsis and yeast COX11 overexpressing cells had the same ROS levels as the corresponding WT. In contrast, the COX11 knock-down and knock-out in Arabidopsis and yeast, respectively, significantly reduced ROS levels. In yeast cells, the ScCOX11 appears to be functionally redundant with superoxide dismutase 1 (ScSOD1), a superoxide detoxifying enzyme. The ΔSccox11ΔScsod1 mutants had dramatically reduced growth on paraquat, compared with the WT or single mutants. This growth retardation does not seem to be linked to the status of the COX complex and cellular respiration. Overexpression of putatively soluble COX11 variants substantially improved the resistance of yeast cells to the ROS inducer menadione. This shows that COX11 proteins can provide antioxidative protection likely independently from their COX assembly function. The conserved Cys219 (in AtCOX11) and Cys208 (in ScCOX11) are important for this function. Altogether, these results suggest that COX11 homologs, in addition to participating in COX complex assembly, have a distinct and evolutionary conserved role in protecting cells during heightened oxidative stress.