Functional Genetics of the Neuronal Sodium Channel Gene SCN8A

描述（由申请人提供）：电压门控钠通道SCN 8A在整个CMS和PNS的神经元中表达，亚细胞定位于轴突起始段、树突和朗维尔结。广泛的表达模式表明，SCN 8A的突变可能会影响大脑和外周神经功能的许多方面。在之前的资助期间，我们在体内产生了用于CRE/loxP靶向条件失活的“floxed”小鼠等位基因。我们还在一个认知缺陷的家族中发现了人类SCN 8A的第一个突变。我们将使用floxed小鼠模型来研究Scnda缺乏对小鼠认知的影响。我们对SCN 8A的5'端非编码外显子和位于第一个编码外显子上游70 kb的启动子进行了鉴定。SCN 8A的5'端非编码外显子含有三个在鱼类、鸡和哺乳动物中进化保守的非编码元件。我们将确定转录调控蛋白与这些网站的亲和力。我们将扩展我们对SCN 8A的人类突变及其在运动障碍和认知功能障碍中的作用的分析。我们将研究在一种新的ENU诱导的小鼠突变体中发现的SCN 8A N-末端结构域中的一种新的错义突变的分子机制。将研究这种突变对运输、蛋白质相互作用和通道活性的影响，以阐明N-末端的作用。总的来说，这项提案将继续进行一项长期的、富有成效的计划，旨在了解必需钠通道SCN 8A在正常功能和疾病中的作用。公共卫生相关性：神经系统疾病和精神疾病之间存在生物连续性。参与神经元信号传导的通道的突变可以影响这两种类型的功能。该项目将使用人类突变的小鼠模型来表征钠通道基因特定变化的神经和行为效应。

DESCRIPTION (provided by applicant): The voltage-gated sodium channel SCN8A is expressed in neurons throughout the CMS and PNS, with subcellular localization in axonal initial segments, dendrites, and nodes of Ranvier. The widespread expression pattern suggests that mutations of SCN8A could affect many aspects of brain and peripheral nerve function. During the previous funding period, we generated a 'floxed' mouse allele for CRE/loxP targeted conditional inactivation in vivo. We also found the first reported mutation of human SCN8A in a family with cognitive deficits. We will use the floxed mouse model to investigate the effects of Scnda deficiency on cognition in the mouse. We have characterized the 5' noncoding exons and promoter of SCN8A which are located 70 kb upstream of the first coding exon. The 5' noncoding exon of SCN8A contains three noncoding elements that are evolutionary conserved in fish, chicken and mammals. We will identify transcriptional regulatory proteins with affinity for these sites. We will extend our analysis of human mutations of SCN8A and their role in movement disorders and cognitive dysfunction. We will investigate the molecular mechanism of a novel missense mutation in the N-terminal domain of SCN8A that we identified in a novel ENU induced mouse mutant. The effect of this mutation on trafficking, protein interaction, and channel activity will be investigated, in order to elucidate the role of the N-terminus. Overall, this proposal will continue a long-term, productive program directed towards understanding the roles of the essential sodium channel SCN8A in normal function and disease. Public health relevance: There is a biological continuum between neurological disease and the psychiatric disorders. Mutations in channels involved in neuronal signalling can affect both types of functions. This project will characterize the neurological and behavioral effects of specific changes in sodium channel genes, using mouse models of human mutations.