Structure and Function of Na+ Channel B Subunits in Adrenal Chromaffin Cells

肾上腺嗜铬细胞Na通道B亚基的结构和功能

• 批准号: 9306878
• 负责人: Lori Isom
• 金额: $ 1.8万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-07-01 至 1995-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9306878&HistoricalAwards=false
• 关键词: Structure; Function; Na+; Channel; Subunits

Voltage-sensitive sodium channels are responsible for the rising phase of the action potential in excitable cells, including central and peripheral neurons, heart, skeletal muscle and neuroendocrine cells. Sodium channels in brain are heterotrimeric complexes composed of alpha, beta-1 and beta-2 subunits, while sodium channels in heart and skeletal muscle are heterodimeric, composed of alpha and beta-1-like subunits. The structure of sodium c channels in neuroendocrine cells has not been identified. Previous work by this investigator has resulted in the molecular cloning and functional expression of the beta-1 subunit of the rat brain sodium channel. Co-expression of cloned beta-1 subunits with alpha subunits in Xenopus oocytes results in increased peak current, acceleration of inactivation, and a shift in the voltage dependence of inactivation to more negative membrane potentials. It is hypothesized that the level of expression and functional properties of sodium channels in excitable cells depends not only on the expression and properties of alpha subunits but also on the expression and functional interaction with beta subunits. The goal of these studies is to identify the sodium channel alpha and beta subunits that are expressed in adrenal medullary chromaffin cells by hybridization to known alpha and beta subunits, determine the structure of chromaffin cell beta subunits by molecular cloning and assess the role of beta subunits in chromaffin cell sodium channel functional expression, including stimulus-secretion coupling . Methods to be employed include: 1) molecular cloning of chromaffin cell sodium channel beta subunits, 2) identification of chromaffin cell sodium channel alpha subunits by hybridization studies, 3) blockade of chromaffin cell sodium channel beta subunit expression in vitro through the use of antisense RNA or antisense oligonucleotides and in vivo through the use of gene disruption experiments, and 4) overexpression of chromaffin cell sodium channel beta subunits by transfection in vitro and by transgenic expression in vivo. %%% Voltage-sensitive sodium channels are an important component of the mechanism by which excitable cells respond to and transmit signals. Examples of excitable cells include nerve cells, muscle cells and neuroendocrine cells. Sodium channels are composed of subunits. The subunit composition of sodium channels differs in different cell types. The subunit structure of sodium channels in neuroendocrine cells, such as chromaffin cells of the adrenal medulla, has not been determined. These studies will use techniques of molecular biology to identify the sodium channel subunits that are expressed in adrenal medullary chromaffin cells and assess their role in chromaffin cell function.

电压敏感性钠离子通道负责升高 可兴奋细胞中动作电位的相位，包括中央 以及外周神经元、心脏、骨骼肌和神经内分泌 细胞 脑钠通道是一种异源三聚体复合物 由α，β-1和β-2亚基组成，而钠 心脏和骨骼肌中的通道是异二聚体， α和β-1亚基。 钠C的结构 神经内分泌细胞中的通道尚未确定。 先前 这位研究人员的工作导致了分子克隆， 大鼠脑钠素β 1亚单位的功能性表达 频道 克隆的β-1亚基与α-亚基的共表达 非洲爪蟾卵母细胞中的亚基导致峰值电流增加， 失活的加速和电压依赖性的转变 使细胞膜电位变得更负。 是 假设表达水平和功能特性 钠离子通道在可兴奋细胞中的作用不仅取决于 α亚基的表达和性质，以及α亚基的表达和性质 表达和与β亚基的功能相互作用。 目标 这些研究之一是识别钠通道α和β 肾上腺髓质嗜铬细胞中表达的亚单位 通过与已知的α和β亚基杂交， 嗜铬细胞β亚单位的分子克隆和结构 评估β亚单位在嗜铬细胞钠通道中的作用 功能性表达，包括刺激-分泌偶联。 方法包括：1）嗜铬蛋白的分子克隆 细胞钠通道β亚基，2）嗜铬细胞的鉴定 细胞钠通道α亚单位杂交研究，3） 阻断嗜铬细胞钠通道β亚单位表达 通过使用反义RNA或反义RNA 寡核苷酸和体内通过使用基因破坏 实验，以及4）嗜铬细胞钠的过度表达 通过体外转染和转基因 体内表达。 %%% 电压敏感性钠通道是细胞膜的重要组成部分， 可兴奋细胞响应和传递的机制 信号. 可兴奋细胞的实例包括神经细胞、肌肉细胞、神经胶质细胞和神经胶质细胞。 细胞和神经内分泌细胞 钠离子通道由 亚单位。 钠通道的亚基组成不同， 不同的细胞类型 细胞膜钠通道的亚基结构 神经内分泌细胞，如肾上腺的嗜铬细胞 骨髓，尚未确定。 这些研究将使用 分子生物学技术鉴定钠通道 肾上腺髓质嗜铬细胞中表达的亚单位 并评估它们在嗜铬细胞功能中的作用。