title: Activation of protein kinase C delta following cerebral ischemia leads to release of cytochrome C from the mitochondria via bad pathway.
abstract: BACKGROUND
  The release of cytochrome c from the mitochondria following cerebral ischemia is a key event leading to cell death. The goal of the present study was to determine the mechanisms involved in post-ischemic activation of protein kinase c delta (δPKC) that lead to cytochrome c release.
  
  
  RESULTS
  We used a rat model of cardiac arrest as an in vivo model, and an in vitro analog, oxygen glucose deprivation (OGD) in rat hippocampal synaptosomes. Cardiac arrest triggered translocation of δPKC to the mitochondrial fraction at 1 h reperfusion. In synaptosomes, the peptide inhibitor of δPKC blocked OGD-induced translocation to the mitochondria. We tested two potential pathways by which δPKC activation could lead to cytochrome c release: phosphorylation of phospholipid scramblase-3 (PLSCR3) and/or protein phosphatase 2A (PP2A). Cardiac arrest increased levels of phosphorlyated PLSCR3; however, inhibition of δPKC translocation failed to affect the OGD-induced increase in PLSCR3 in synaptosomal mitochondria suggesting the post-ischemic phosphorylation of PLSCR3 is not mediated by δPKC. Inhibition of either δPKC or PP2A decreased cytochrome c release from synaptosomal mitochondria. Cardiac arrest results in the dephosphorylation of Bad and Bax, both downstream targets of PP2A promoting apoptosis. Inhibition of δPKC or PP2A prevented OGD-induced Bad, but not Bax, dephosphorylation. To complement these studies, we used proteomics to identify novel mitochondrial substrates of δPKC.
  
  
  CONCLUSIONS
  We conclude that δPKC initiates cytochrome c release via phosphorylation of PP2A and subsequent dephosphorylation of Bad and identified δPKC, PP2A and additional mitochondrial proteins as potential therapeutic targets for ischemic neuroprotection.
authors.affiliation: Cerebral Vascular Disease Research Center, Department of Neurology, Leonard M. Miller School of Medicine, University of Miami, Miami, Florida, United States of America.
authors.forename: Kunjan R
authors.initials: KR
authors.lastname: Dave
authors.forename: Sanjoy K
authors.initials: SK
authors.lastname: Bhattacharya
authors.forename: Isabel
authors.initials: I
authors.lastname: Saul
authors.forename: R Anthony
authors.initials: RA
authors.lastname: DeFazio
authors.forename: Cameron
authors.initials: C
authors.lastname: Dezfulian
authors.forename: Hung Wen
authors.initials: HW
authors.lastname: Lin
authors.forename: Ami P
authors.initials: AP
authors.lastname: Raval
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Perez-Pinzon
mesh_terms: D000818:Animals; D002545:Brain Ischemia / Q000201:enzymology* / Q000473:pathology*; D045304:Cytochromes c / Q000378:metabolism*; D004789:Enzyme Activation; D005947:Glucose / Q000172:deficiency; D008297:Male; D008928:Mitochondria / Q000378:metabolism*; D008954:Models, Biological; D010100:Oxygen / Q000378:metabolism; D049294:Phospholipid Transfer Proteins / Q000378:metabolism; D010766:Phosphorylation; D051745:Protein Kinase C-delta / Q000378:metabolism*; D054648:Protein Phosphatase 2 / Q000378:metabolism; D021381:Protein Transport; D040901:Proteomics; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D013379:Substrate Specificity; D051028:bcl-2-Associated X Protein / Q000378:metabolism; D051025:bcl-Associated Death Protein / Q000378:metabolism*
chemical_list: D049294:Phospholipid Transfer Proteins; D051028:bcl-2-Associated X Protein; D051025:bcl-Associated Death Protein; D045304:Cytochromes c; D051745:Protein Kinase C-delta; D054648:Protein Phosphatase 2; D005947:Glucose; D010100:Oxygen