HEREDITARY DEFECTS IN HUMAN SODIUM CHANNELS

人体钠通道的遗传性缺陷

• 批准号: 2270542
• 负责人: Alfred L. George
• 金额: $ 20.68万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1994
• 资助国家: 美国
• 起止时间: 1994-01-01 至 1997-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2270542
• 关键词: Xenopus; Xenopus oocyte; electrophysiology; familial periodic paralysis; family genetics; gene mutation; human subject; hyperkalemias; hypokalemia; inborn biological transport disorder; membrane potentials; molecular cloning; molecular pathology; protein structure function; recombinant DNA; site directed mutagenesis; sodium channel; striated muscles; voltage gated channel

Voltage-dependent Na+ channels are responsible for the rapid membrane depolarization that characterizes the initial phase of an action potential in nerve, heart and muscle. In skeletal muscle, failure of Na+ channel function will lead to paralysis in spite of normal nerve, neuromuscular junction, and contractile protein function. In hereditary periodic paralysis, paroxysmal weakness is a manifestation of a defect in the muscle Na+ channel which can episodically render the myocyte electrically inexcitable. During the past two years, we and others have elucidated the molecular basis of these genetic diseases by demonstrating mutations in the human muscle Na+ channel alpha-subunit gene (SCN4A). We now know that at least nine distinct point mutations in the SCN4A gene may cause hyperkalemic periodic paralysis and paramyotonia congenita, but not hypokalemic paralysis. This research proposal outlines studies aimed at examining the dysfunction conferred by these various hereditary defects on the human muscle Na+ channel. The approach will involve a fusion of recombinant DNA technology and cellular electrophysiology. Site-directed mutagenesis will be used to create mutant Na+ channel alpha-subunit, hSkM1, will be used for these studies. Electrophysiological studies using heterologous expression of hSkM1 mutants in transfected mammalian cells will be used to define abnormal phenotypes. We will also examine the role of the Na+ channel beta1-subunit in expression of disease-producing mutant channel phenotypes. These studies will involve, in part, engineering the periodic paralysis mutations in the human cardiac Na+ channel (hH1), a channel which functions normally without the beta1-subunit. If Na+ channel alpha-subunit defects are not dependent on beta1, then mutations in hH1 patterned after those in periodic paralysis should have functional consequences. We also hypothesize that defects in the beta1-subunit gene cause hypokalemic periodic paralysis and will test this by genetic linkage analysis. This work should contribute greatly to our understanding of hereditary disorders of muscle membrane excitability, and to the structure and function of voltage-dependent Na+ channels.

电压依赖性Na+通道负责快速膜 表征动作初始阶段的去极化 潜在的神经，心脏和肌肉。 在骨骼肌肉中，Na+失败 尽管神经正常，但通道功能仍会导致瘫痪 神经肌肉连接和收缩蛋白功能。 在世袭 周期性麻痹，阵发性无力是缺陷的表现 在肌肉Na+通道中，可以发作呈现心肌细胞 电气不可能。 在过去的两年中，我们和其他人阐明了分子 这些遗传疾病的基础通过证明人类突变 肌肉Na+通道α-亚基基因（SCN4A）。 我们现在至少知道 SCN4a基因中的九个不同点突变可能会引起高钾血症 周期性瘫痪和帕诺托尼亚豆科氏菌，但不是降低性的 麻痹。 该研究建议概述了旨在检查的研究 这些各种遗传缺陷赋予的功能障碍 人NA+通道。 该方法将涉及融合 重组DNA技术和细胞电生理学。 站点定向 诱变将用于创建突变体na+通道α-亚基， HSKM1将用于这些研究。 电生理研究 使用转染的哺乳动物中HSKM1突变体的异源表达 细胞将用于定义异常表型。 我们还将检查Na+通道Beta1-Subunit在 产生疾病的突变通道表型的表达。 这些研究 将部分涉及到周期性瘫痪突变 人类心脏Na+通道（HH1），该通道正常起作用 没有beta1-subunit。 如果Na+通道alpha-subunit缺陷不是 依赖于beta1，然后在HH1中进行突变。 周期性麻痹应具有功能后果。 我们也是 假设Beta1-Subunit基因中的缺陷导致降低性降低 周期性瘫痪，并将通过遗传链接分析进行测试。 这项工作应该为我们对世袭的理解做出很大贡献 肌肉膜兴奋性的疾病以及结构和 电压依赖性Na+通道的功能。