Antiepileptic action of JNK2 inhibition

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Project summary / abstract c-Jun N-terminal kinases (JNKs) are a family of protein kinases that are members of the larger category of “stress activated protein kinases.” JNKs are known to be hyperactivated in neurodegenerative disorders such as Alzheimer’s disease, Parkinson’s disease, and are more recently implicated in medically refractory epilepsy. In these diseases, hyperactivation of JNK is a pathological event, and appears to contribute to the progressive apoptotic death of neurons. We recently found, somewhat unexpectedly, that JNK is hyperactivated in an animal model of temporal lobe epilepsy, and that partial pharmacological inhibition of JNK produced a significant, dose-dependent reduction of spontaneous seizure frequency in chronically epileptic animals. In addition, of the three JNK isoforms (JNK1, 2, and 3), only JNK2 was hyperactivated in our animal model. Thus, we hypothesized that selective inhibition of JNK2 could produce a significant antiepileptic action and avoid potential CNS adverse effects of broad spectrum JNK inhibition. In this two-year, focused proposal we plan to further study JNK as a novel target of antiepileptic therapy. In the first Aim, we will seek more complete knockdown of JNK2 expression in an animal model of epilepsy using a novel AAV-delivered CRISPR/Cas9 approach. Published data shows that this approach is capable of knocking down gene expression to a degree comparable to that of constitutive gene deletion. We will measure the effect of near- complete JNK2 knockdown on spontaneous seizure frequency in an animal model of temporal lobe epilepsy. In the second Aim, we will seek evidence that JNKs are hyperactivated in human epilepsy as they are in our animal model by looking for total and phosphorylated (activated) JNK expression for all three isoforms in brain tissue from human epilepsy patients undergoing brain resection for medically refractory epilepsy. We will also measure JNK expression and activation in cerebrospinal fluid from refractory epilepsy patients compared to individuals without a neurological disorder. These experiments will provide further validation of JNK as a novel target of antiepileptic therapy. Such targets are desperately needed in order to advance therapy for patients with medically refractory epilepsy.