Na+/H+ exchange in the nematode intestine

线虫肠道中的Na/H交换

• 批准号: 6727712
• 负责人: Keith Nehrke
• 金额: $ 15.75万
• 依托单位: UNIVERSITY OF ROCHESTER
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-01 至 2005-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6727712
• 关键词: Caenorhabditis elegans; acidity /alkalinity; bioenergetics; gastrointestinal nutrient absorption; glucose transporter; green fluorescent proteins; helminth genetics; mutant; nutrient intake activity; nutrition related tag; oxygen consumption; protein isoforms; protein localization; protein structure function; protein transport; sodium hydrogen exchanger; superoxides; transposon /insertion element

DESCRIPTION (provided by applicant): Deficiencies in Na+/H+ exchange compromise fluid and electrolyte transport in the mammalian intestine. In addition, nutrient absorption via H+-coupled peptide transporters and Na+-glucose co-transporters is pH dependent, and may depend upon intracellular pH regulation through Na+/H + exchange in order to remain active. Although a great deal is known about the structure and function of several Na+/H+ exchanger proteins, to date little is known about the remaining family members. In this proposal, we intend to develop a physiologically simple model system where the role of individual Na+/H+ exchangers in mediating intestinal function can be assessed on a genome-wide level in an intact animal. Towards this end, we have cloned the cDNAs for nine Na+/H+ exchangers from the nematode C. elegans. Aim 1 of this proposal involves determining the cellular, subcellular and temporal expression patterns of these exchangers. Aim 2 is designed to directly test the physiological role of each exchanger in vivo using double-stranded RNA-mediated gene interference in combination with a novel system to measure intracellular pH in an intact nematode, using GFP as a targetable, non-invasive intracellular pH indicator. Preliminary results suggest that nhx-2, an intestinal Na+/H+ exchanger, is involved in regulating the post-embryonic growth of early larval stage nematodes. Thus, Aim 3 is designed to directly assess the role of this exchanger in mediating nutrient absorption. Using a transposon insertion mutant that lacks nhx-2 gene function, we will examine the uptake of nutrients from a bacterial food source and also assess markers of metabolic potential such as oxygen consumption, superoxide production, and ATP/ADP concentrations. This multidisciplinary approach will help to define the biological role of individual Na+/H+ exchangers in the nematode intestine.

描述（由申请人提供）：Na+/H+交换的缺陷会损害哺乳动物肠道中的液体和电解质运输。此外，通过H+偶联肽转运蛋白和Na+-葡萄糖共转运蛋白的营养吸收是pH依赖性的，并且可能依赖于通过Na+/H+交换进行的细胞内pH调节以保持活性。尽管人们对几种 Na+/H+ 交换蛋白的结构和功能了解很多，但迄今为止，对其余家族成员知之甚少。在本提案中，我们打算开发一个生理上简单的模型系统，可以在完整动物的全基因组水平上评估单个 Na+/H+ 交换器在介导肠道功能中的作用。为此，我们从线虫秀丽隐杆线虫中克隆了 9 个 Na+/H+ 交换剂的 cDNA。该提案的目标 1 涉及确定这些交换器的细胞、亚细胞和时间表达模式。目标 2 旨在使用双链 RNA 介导的基因干扰与测量完整线虫细胞内 pH 值的新系统相结合，使用 GFP 作为可靶向、非侵入性细胞内 pH 值，直接测试体内每个交换器的生理作用指标。初步结果表明，nhx-2是一种肠道Na+/H+交换剂，参与调节早期幼虫期线虫的胚胎后生长。因此，目标 3 旨在直接评估该交换器在介导营养吸收中的作用。使用缺乏 nhx-2 基因功能的转座子插入突变体，我们将检查细菌食物来源中营养物质的吸收，并评估代谢潜力的标记，例如耗氧量、超氧化物产生和 ATP/ADP 浓度。这种多学科方法将有助于确定线虫肠道中单个 Na+/H+ 交换器的生物学作用。