Animals
Blotting, Western
Brain Ischemia/*enzymology/pathology
Cerebrovascular Circulation/physiology
Enzyme Activation/physiology
Membrane Potential, Mitochondrial
Mice
Mitochondria/*enzymology
Protein Kinase C-epsilon/*metabolism
Reactive Oxygen Species/metabolism
Reperfusion Injury/enzymology/pathology
Stroke/*enzymology/pathology
Activation of protein kinase C (PKC) confers protection against neuronal ischemia/reperfusion. Activation of PKC leads to its translocation to multiple intracellular sites, so a mitochondria-selective PKC activator was used to test the importance of mitochondrial activation to the neuroprotective effect of PKC. PKC can regulate key cytoprotective mitochondrial functions, including electron transport chain activity, reactive oxygen species (ROS) generation, mitochondrial permeability transition, and detoxification of reactive aldehydes. We tested the ability of mitochondria-selective activation of PKC to protect primary brain cell cultures or mice subjected to ischemic stroke. Pretreatment with either general PKC activator peptide, TAT-PsiRACK, or mitochondrial-selective PKC activator, TAT-PsiHSP90, reduced cell death induced by simulated ischemia/reperfusion in neurons, astrocytes, and mixed neuronal cultures. The protective effects of both TAT-PsiRACK and TAT-PsiHSP90 were blocked by the PKC antagonist V1-2 , indicating that protection requires PKC interaction with its anchoring protein, TAT-RACK. Further supporting a mitochondrial mechanism for PKC, neuroprotection by TAT-PsiHSP90 was associated with a marked delay in mitochondrial membrane depolarization and significantly attenuated ROS generation during ischemia. Importantly, TAT-PsiHSP90 reduced infarct size and reduced neurological deficit in C57/BL6 mice subjected to middle cerebral artery occlusion and 24 hr of reperfusion. Thus selective activation of mitochondrial PKC preserves mitochondrial function in vitro and improves outcome in vivo, suggesting potential therapeutic value clinically when brain ischemia is anticipated, including neurosurgery and cardiac surgery.Activation of protein kinase C (PKC) confers protection against neuronal ischemia/reperfusion. Activation of PKC leads to its translocation to multiple intracellular sites, so a mitochondria-selective PKC activator was used to test the importance of mitochondrial activation to the neuroprotective effect of PKC. PKC can regulate key cytoprotective mitochondrial functions, including electron transport chain activity, reactive oxygen species (ROS) generation, mitochondrial permeability transition, and detoxification of reactive aldehydes. We tested the ability of mitochondria-selective activation of PKC to protect primary brain cell cultures or mice subjected to ischemic stroke. Pretreatment with either general PKC activator peptide, TAT-PsiRACK, or mitochondrial-selective PKC activator, TAT-PsiHSP90, reduced cell death induced by simulated ischemia/reperfusion in neurons, astrocytes, and mixed neuronal cultures. The protective effects of both TAT-PsiRACK and TAT-PsiHSP90 were blocked by the PKC antagonist V1-2 , indicating that protection requires PKC interaction with its anchoring protein, TAT-RACK. Further supporting a mitochondrial mechanism for PKC, neuroprotection by TAT-PsiHSP90 was associated with a marked delay in mitochondrial membrane depolarization and significantly attenuated ROS generation during ischemia. Importantly, TAT-PsiHSP90 reduced infarct size and reduced neurological deficit in C57/BL6 mice subjected to middle cerebral artery occlusion and 24 hr of reperfusion. Thus selective activation of mitochondrial PKC preserves mitochondrial function in vitro and improves outcome in vivo, suggesting potential therapeutic value clinically when brain ischemia is anticipated, including neurosurgery and cardiac surgery.