STRESS ACTIVATED PROTEIN KINASE IN NEURONAL APOPTOSIS

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Glutamate excitotoxicity is the presumed mechanism underlying many neurological disorders including acute ischemia and chronic neurodegeneration. Recent work from our laboratories demonstrated that mice lacking the neural isoform of the stress activated protein kinsase SAPK/JNK (JNK3) has remarkable resistance to kainic acid-induced seizures, AP-1 transcriptional activity and apoptosis of hippocampal neurons. These results strongly suggest that the SAPK/JNK signaling pathway is a critical component in the pathogenesis of glutamate excitotoxicity. Based on this hypothesis, the present proposal comprises two sets of closely related in vitro and in vivo experiments. Specific Aim I: Mechanism of JNK -mediated glutamate neurotoxicity ( in vitro studies). Keys issues to be addressed include: (1) the JNK - mediated neurotoxicity through gene regulation and de novo biosynthesis; (2) the regulation of intracellular calcium oscillation through JNK signaling; (3) the interplay between JNK - signaling And oxidative stress, (4) the specificity of activation route of JNK signaling. These potential mechanisms will be tested in primary culture of dissociated neurons using a combination of morphological, physiological and biochemical approaches. Specific Aim II: Neuroprotection of the blockade JNK signaling pathway (in vivo studies) Potential clinical applications of inhibition of the JNK signaling may include: (1) the prevention of ischemic apoptosis; (2) attenuation of chronic glutamate excitotoxicity in amytrophic lateral sclerosis; (3) the prevention of neurodegneration (4) enhanced survival of grafted neurons in transplantation therapy. Preliminary evidence of feasibility has been obtained for each Specific Aim. The potential applications will be tested in experimental models of neuropathology using wildtype and mutant mice lacking the neural-specific JNK3 isoform. In summary, the overall goal of the present proposal is both to understand the mechanism underlying JNK- mediated glutamate neurotoxicity and to test the clinical potential of targeting the JNK signaling pathway for therapeutic intervention.