Structural studies of NaV1.5 and functional implications.

NaV1.5 的结构研究和功能意义。

基本信息

批准号：
9443872
负责人：
Geoffrey S Pitt
金额：
$ 38.7万
依托单位：
WEILL MEDICAL COLL OF CORNELL UNIV
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-07-01 至 2018-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9443872
关键词：
Structural studies NaV1.5 functional implications.

项目摘要

DESCRIPTION (provided by applicant): Voltage-gated Na channels (NaV) initiate electrical impulses in neurons and the heart. Mutations in SCN1A and SCN2A, which encode the neuronal channels NaV1.1 and NaV1.2, respectively, cause inherited epilepsy syndromes. Mutations in SCN5A, which encodes the major subtype of NaV channel in heart (NaV1.5), are linked to many cardiac arrhythmogenic disorders, such as Long QT syndrome (LQTS) and Brugada syndrome (BrS). The main structural components of NaV channels are four homologous repeats, which assemble in a tetrameric configuration within the membrane to control voltage-dependent Na+ conduction, and a cytosolic C-terminal domain (CTD) that serves as a binding site for many auxiliary regulatory proteins and is a hotspot for disease-causing mutations. Among these auxiliary CTD-interacting proteins, the ubiquitous Ca2+ sensor calmodulin (CaM) and fibroblast growth factor homologous factors (FHFs; FGF11-FGF14) are of particular interest: many disease- causing mutations are localized to their putative interaction domains within the CTDs of specific NaV channels; FGF14 is itself a locus for the neurodegenerative disorder spinocerebellar ataxia 27; and Ca2+ regulation of NaV channels by CaM is poorly understood. A lack of structural information for these interactions with the CTD, however, has prevented an understanding of the roles of the CTDs, these auxiliary proteins in channel regulation, and the molecular basis of mutational effects on NaV that lead to disease. Building on recent success in determining the crystal structure of a NaV CTD in complex with CaM and an FHF; and in defining new roles for FHFs in regulation of NaV channel gating and trafficking, we propose to define the mechanisms of NaV channel regulation by Ca2+/CaM, and FHFs and to uncover the molecular basis of the mutational effects on NaV CTDs and their associated proteins that lead to channelopathies. To achieve these goals, we propose the following specific aims: 1. Structure-function studies to determine how Ca2+/CaM regulate NaV channel function, using electrophysiology and biochemistry, to probe insights gained from structural determination; 2. Structure-function studies to determine how FHFs regulate NaV channel function and how FHFs co-operate with CaM for channel regulation; 3. Physiological investigations of the consequences of FHF regulation of NaV1.5. Because NaV channelopathies and mutations in FHFs are associated with neurodegenerative diseases, epilepsy syndromes, and cardiac arrhythmias, the proposed project has great potential to illuminate the molecular basis of multiple channelopathies in multiple organ systems due to NaV CTD mutations and, more generally, to uncover fundamental aspects of NaV channel structure-function.

描述（由申请人提供）：电压门控的NA通道（NAV）启动神经元和心脏中的电脉冲。 SCN1A和SCN2A中的突变分别编码神经元通道NAV1.1和NAV1.2，导致遗传性癫痫综合症。 SCN5a中的突变（NAV1.5）编码了NAV通道的主要亚型（NAV1.5），与许多心脏心律失常性疾病有关，例如长QT综合征（LQTS）和Brugada综合征（BRS）。 NAV通道的主要结构组件是四个同源重复序列，它们在膜内的四聚体构型组装中，以控制电压依赖性Na+传导，以及一个胞质C末端结构域（CTD），可作为许多辅助调节蛋白的结合位点，是许多辅助调节蛋白的结合位点，是一种用于疾病 - ca-ca-caise-caise-caise-Caise-Caise-Caise-Caise-Caise-Caise-Caise-Caise-Caise-Caise-Caise-Caise-Caise-Caise-Caise-Caise-Caise-Caise-Caise-Caise-Caise。在这些辅助CTD相互作用蛋白中，无处不在的Ca2+传感器钙调蛋白（CAM）和成纤维细胞生长因子同源因子（FHFS; FGF11-FGF14）尤其感兴趣：许多疾病引起的突变被定位于其在其特定海军通道的CTD中的cut性相互作用域局部。 FGF14本身就是神经退行性疾病脊髓脑性共济失调27的轨迹； CAM对NAV通道的CA2+调节尚不清楚。然而，缺乏与CTD相互作用的结构信息，阻止了对CTD的作用，这些辅助蛋白在通道调节中的作用以及导致疾病的NAV的突变作用的分子基础。基于最近成功地确定与CAM和FHF复合体中NAV CTD的晶体结构的基础；在定义FHF在调节NAV通道门控和运输中的新作用时，我们建议定义CA2+/CAM和FHF的NAV通道调节机制，并揭示突变对NAV CTD的分子基础，对NAV CTDS及其相关蛋白导致通道病的相关蛋白。为了实现这些目标，我们提出了以下特定目标：1。结构功能研究，以确定CA2+/CAM使用电生理学和生物化学来调节NAV通道功能，以探测从结构确定中获得的见解； 2。结构功能研究，以确定FHF如何调节NAV通道功能以及FHFS如何与CAM合作以进行通道调节； 3。对FHF调节NAV1.5的后果的生理研究。由于FHF中的NAV通道病和突变与神经退行性疾病，癫痫综合征和心律不齐有关，因此提议的项目具有很大的潜力，可以阐明由于NAV CTD突变而导致多个器官系统中多个通道病的分子基础，并且由于NAV CTD突变以及更全面的基本范围的范围源于导致导航的基本方面。