Identification of ?PKC targets during cardiac ischemic injury.

ABSTRACT: BACKGROUND:Epsilon-protein kinase C (?PKC) protects the heart from ischemic injury. However, the mechanism(s) of ?PKC cardioprotection is still unclear. Identification of the ?PKC targets may aid in elucidating the ?PKC-mediated cardioprotective mechanisms. Previous studies, using ?PKC transgenic mice and difference in gel electrophoresis, identified proteins involved in glucose metabolism, the expression of which was modified by ?PKC. Those studies were accompanied by metabolomic analysis, suggesting that increased glucose oxidation may be responsible for the cardioprotective effect of ?PKC. Whether these ?PKC-mediated alterations were because of differences in protein expression or phosphorylation was not determined. METHODS AND RESULTS:In the present study, we used an ?PKC -specific activator peptide, ??RACK, combined with phosphoproteomics, to find ?PKC targets, and identified that the proteins whose phosphorylation was altered by selective activation of ?PKC were mostly mitochondrial proteins. Analysis of the mitochondrial phosphoproteome led to the identification of 55 spots, corresponding to 37 individual proteins, exclusively phosphorylated, in the presence of ??RACK. The majority of the proteins identified were involved in glucose and lipid metabolism, components of the respiratory chain as well as mitochondrial heat shock proteins. CONCLUSIONS:The protective effect of ?PKC during ischemia involves phosphorylation of several mitochondrial proteins involved in glucose and lipid metabolism and oxidative phosphorylation. Regulation of these metabolic pathways by ?PKC phosphorylation may lead to ?PKC-mediated cardioprotection induced by ??RACK.

SUBMITTER: Budas G 

PROVIDER: S-EPMC3527096 | biostudies-literature | 2012

REPOSITORIES: biostudies-literature