The Journal of Neuroscience, April 16, 2008, 28(16):4172-4182; doi:10.1523/JNEUROSCI.5471-07.2008
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Neurobiology of Disease
Ischemic Preconditioning Targets the Respiration of Synaptic Mitochondria via Protein Kinase C
Kunjan R. Dave,1
R. Anthony DeFazio,1
Ami P. Raval,1
Alessandra Torraco,2
Isabel Saul,1
Antoni Barrientos,1,2,3 and
Miguel A. Perez-Pinzon1,2
1The Cerebral Vascular Disease Research Center, 2Department of Neurology and Neuroscience Program, and 3Department of Biochemistry and Molecular Biology and The John T. MacDonald Center for Medical Genetics, Leonard M. Miller School of Medicine, University of Miami, Miami, Florida 33136
Correspondence should be addressed to Dr. Miguel A. Perez-Pinzon, Department of Neurology, D4-5, University of Miami Miller School of Medicine, P.O. Box 016960, Miami, FL 33101. Email: perezpinzon{at}miami.edu
In the brain, ischemic preconditioning (IPC) diminishes mitochondrial dysfunction after ischemia and confers neuroprotection. Activation of 
protein kinase C (PKC) has been proposed to be a key neuroprotective pathway during IPC. We tested the hypothesis that IPC increases the levels of PKC in synaptosomes from rat hippocampus, resulting in improved synaptic mitochondrial respiration. Preconditioning significantly increased the level of hippocampal synaptosomal PKC to 152% of sham-operated animals at 2 d of reperfusion, the time of peak neuroprotection. We tested the effect of PKC activation on hippocampal synaptic mitochondrial respiration 2 d after preconditioning. Treatment with the specific PKC activating peptide, tat-
RACK (tat--receptor for activated C kinase), increased the rate of oxygen consumption in the presence of substrates for complexes I, II, and IV to 157, 153, and 131% of control (tat peptide alone). In parallel, we found that PKC activation in synaptosomes from preconditioned animals resulted in altered levels of phosphorylated mitochondrial respiratory chain proteins: increased serine and tyrosine phosphorylation of 18 kDa subunit of complex I, decreased serine phosphorylation of FeS protein in complex III, increased threonine phosphorylation of COX IV (cytochrome oxidase IV), increased mitochondrial membrane potential, and decreased H2O2 production. In brief, ischemic preconditioning promoted significant increases in the level of synaptosomal PKC. Activation of PKC increased synaptosomal mitochondrial respiration and phosphorylation of mitochondrial respiratory chain proteins. We propose that, at 48 h of reperfusion after ischemic preconditioning, PKC is poised at synaptic mitochondria to respond to ischemia either by direct phosphorylation or activation of the PKC signaling pathway.
Key words: cerebral ischemia; phosphorylation; electron transport chain; neuroprotection; cell death; hippocampus
Received June 26, 2007;
revised Feb. 29, 2008;
accepted March 2, 2008.
Correspondence should be addressed to Dr. Miguel A. Perez-Pinzon, Department of Neurology, D4-5, University of Miami Miller School of Medicine, P.O. Box 016960, Miami, FL 33101. Email: perezpinzon{at}miami.edu
