title: Mitochondrial c-Src regulates cell survival through phosphorylation of respiratory chain components.
abstract: Mitochondrial protein tyrosine phosphorylation is an important mechanism for the modulation of mitochondrial functions. In the present study, we have identified novel substrates of c-Src in mitochondria and investigated their function in the regulation of oxidative phosphorylation. The Src family kinase inhibitor PP2 {amino-5-(4-chlorophenyl)-7-(t-butyl) pyrazolo [3,4d] pyrimidine} exhibits significant reduction of respiration. Similar results were obtained from cells expressing kinase-dead c-Src, which harbours a mitochondrial-targeting sequence. Phosphorylation-site analysis selects c-Src targets, including NDUFV2 (NADH dehydrogenase [ubiquinone] flavoprotein 2) at Tyr(193) of respiratory complex I and SDHA (succinate dehydrogenase A) at Tyr(215) of complex II. The phosphorylation of these sites by c-Src is supported by an in vivo assay using cells expressing their phosphorylation-defective mutants. Comparison of cells expressing wild-type proteins and their mutants reveals that NDUFV2 phosphorylation is required for NADH dehydrogenase activity, affecting respiration activity and cellular ATP content. SDHA phosphorylation shows no effect on enzyme activity, but perturbed electron transfer, which induces reactive oxygen species. Loss of viability is observed in T98G cells and the primary neurons expressing these mutants. These results suggest that mitochondrial c-Src regulates the oxidative phosphorylation system by phosphorylating respiratory components and that c-Src activity is essential for cell viability.
authors: Department of Biomolecular Science, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan.
authors: Masato
authors: M
authors: Ogura
authors: Junko
authors: J
authors: Yamaki
authors: Miwako K
authors: MK
authors: Homma
authors: Yoshimi
authors: Y
authors: Homma
mesh_terms: D000818:Animals; D000081247:CSK Tyrosine-Protein Kinase; D045744:Cell Line, Tumor; D002470:Cell Survival; D004579:Electron Transport / Q000502:physiology*; D042963:Electron Transport Complex II / Q000378:metabolism; D006801:Humans; D051379:Mice; D008928:Mitochondria / Q000201:enzymology / Q000378:metabolism*; D009245:NADH Dehydrogenase / Q000378:metabolism; D010101:Oxygen Consumption; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism*; D019061:src-Family Kinases / Q000378:metabolism*
chemical_list: D042963:Electron Transport Complex II; C511268:SDHA protein, human; D009245:NADH Dehydrogenase; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; C000631346:CSK protein, human; C492562:NDUFV2 protein, human