Article

Mitochondrial c-Src regulates cell survival through phosphorylation of respiratory chain components.

Department of Biomolecular Science, Fukushima Medical University School of Medicine, Fukushima 960-1295, Japan.
Biochemical Journal (impact factor: 4.9). 07/2012; 447(2):281-9. DOI:10.1042/BJ20120509 pp.281-9
Source: PubMed

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 Tyr193 of respiratory complex I and SDHA (succinate dehydrogenase A) at Tyr215 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.

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Keywords

cell viability
 
cellular ATP content
 
induces reactive oxygen species
 
kinase-dead c-Src
 
mitochondrial c-Src regulates
 
mitochondrial functions
 
Mitochondrial protein tyrosine phosphorylation
 
mitochondrial-targeting sequence
 
NADH dehydrogenase activity
 
NDUFV2 phosphorylation
 
novel substrates
 
oxidative phosphorylation
 
oxidative phosphorylation system
 
perturbed electron transfer
 
phosphorylation-defective mutants
 
Phosphorylation-site analysis
 
SDHA phosphorylation
 
Src family kinase inhibitor PP2 {amino-5-(4-chlorophenyl)-7-(t-butyl)
 
T98G cells
 
vivo assay
 

Masato Ogura