Molecular mechanisms underlying cardiac sodium channelopathy

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Project Summary: The cardiac voltage-gated sodium channel, NaV1.5, plays an important role in cardiac function. Genetic mutations in NaV1.5 are known to be associated with various cardiac arrhythmias including long QT syndrome. Our preliminary results suggested that NaV1.5 channel is regulated by cyclin-dependent kinase 5 (CDK5) and that CDK5 and NaV1.5 channel are involved in cardiac arrhythmias caused by genetic mutations in the CACNA1C calcium channel and MYH7 myofilament genes. The primary goal of this study is to unveil the molecular mechanisms of cardiac NaV1.5 channel regulation and to elucidate the pathophysiological mechanisms underlying cardiac arrhythmias associated with sodium channelopathy. Aim 1 is to examine how CDK5 regulates NaV1.5 channels using human and mouse models with electrophysiological recordings. Aim 2 is to elucidate how cardiac sodium channel dysfunction results from the cardiac calcium channel mutants in long QT syndrome type 8. Aim 3 is to test the hypothesis that CDK5 and NaV1.5 abnormalities are involved in familial hypertrophic cardiomyopathy and arrhythmias that are caused by a familial MYH7 mutation. The approaches of our study would provide new insights into the molecular basis of cardiac sodium channel regulation and the pathophysiological mechanisms underlying cardiac arrhythmias with sodium channelopathy.