Neurocardiac mechanisms of epilepsy with high risk of SUDEP

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PROJECT SUMMARY/ABSTRACT Our long-term goal is to understand how gene mutations can cause epilepsy with cardiorespiratory comorbidities that contribute to risk of sudden unexpected death in epilepsy (SUDEP). People with epilepsy are 24 times more likely than the general population to die suddenly for unknown pathological reasons; these deaths are classified as SUDEP and represent the leading cause of epilepsy-related mortality. SUDEP is hypothesized to result from seizure-driven cardiorespiratory dysfunction that culminates in death. This proposal investigates the contribution of Kcna1 gene deletion to epilepsy, cardiac dysfunction, and SUDEP by using Cre recombinase-mediated conditional knockout models. Kcna1, a human epilepsy gene associated with SUDEP risk in patients, encodes predominantly-axonal Kv1.1 voltage-gated potassium channel α-subunits that are highly expressed in brain where they act to dampen neuronal excitability. Although the epilepsy phenotype of Kcna1-null mice has been studied extensively, the mechanisms and anatomical substrates responsible for their seizures, cardiac dysfunction and sudden death are poorly understood. In addition, new preliminary data reveals that Kcna1 is expressed in cardiomyocytes as well as brain; therefore, Kv1.1-deficiency in either organ could be sufficient to mediate cardiac arrhythmias and death. Utilizing a newly developed floxed Kcna1 mouse allele, the goal of this project is to test the hypotheses that brain region-specific Kv1.1-deficiency is sufficient to cause the epilepsy, cardiac phenotypes, and SUDEP observed in Kcna1-null mice and that the Kv1.1-deficient heart provides a permissive substrate for seizure- related cardiac abnormalities. Aim 1 examines neurocardiac effects of neuron-, corticolimbic-, and hindbrain- specific Kcna1 gene deletion. Aim 2 investigates cardiac dysfunction due to cardiac-specific Kcna1 gene deletion, as well as intrinsic dysfunction in denervated isolated hearts from global KOs. Aim 3 uses kainate- induced seizures in cardiac-specific cKOs to test whether Kv1.1-deficient hearts are inherently more prone to seizure-related functional and cardiac abnormalities. This research applies an innovative genetic approach to the study of brain-heart interactions in epilepsy by exploiting newly developed transgenic mouse models of SUDEP. These models allow us to identify previously unrecognized brain networks important for SUDEP pathophysiology and neurocardiac control, establishing them as candidate therapeutic targets for future studies. Furthermore, this study will improve our understanding of Kcna1 gene function and its role in human neurological and cardiac diseases.