Optimal post-seizure therapy requires anticonvulsant and neuroprotectant therapeutic strategies, as both prolonged seizures (status epilepticus) and repetitive seizures occurring over time (epilepsy) cause neuronal death in brain and cognitive decline. Our data challenge assumptions on the relevant molecular pathways for such neuronal loss, revealing that Death Receptors of the extrinsic pathway are preferentially activated following seizures, which then trigger endoplasmic reticulum (ER) dysfunction. This extrinsic pathway activation occurs before any (intrinsic) mitochondria-linked cell death pathways become activated. We show protection from extrinsic pathway activation by ER-resident anti-apoptotic Bcl-w, which functions through effects on calcium regulation, attenuation of ER based pro-apoptotic Bcl-2 family protein function and inhibition of the integral ER membrane BAP31 complex.
The SPECIFIC AIMS of this project are:
Aim 1. Determine the significance and mechanism of death receptor complex activation as a cause of ER dysfunction and neuronal death following seizures.
Aim 2. Determine how Bcl-w protects against seizure-induced neuronal death via effects on the extrinsic pathway target:
Aim 3. Show the relationship between Extrinsic and Intrinsic pathway activation by seizures. To accomplish these aims we have developed a mouse model of seizure-induced brain injury, not previously available, with continual EEC seizure monitoring, permitting electrographic seizure quantitation and distinction between injurious and non-injurious seizure types. We also use an in vitro seizure model permitting single cell, calcium imaging and culture studies. With mouse modeling we will use knockouts for down regulation of apoptosis modulatory genes under study and provide up-regulation of protective gene products with adenoassociated viruses and TAT fusion proteins. We determine the effect of pharmacological and molecular manipulation of the extrinsic cell death pathway on seizure induced cell damage. Finally, using continuous video-EEC monitoring, we will investigate how prevention of neuronal damage following seizures effects the development of an epileptic phenotype.
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