CORE--ELECTROPHYSIOLOGY CORE

核心--电生理核心

• 批准号: 7210583
• 负责人: Chou-Long Huang
• 金额: $ 17.96万
• 依托单位: UT SOUTHWESTERN MEDICAL CENTER
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7210583
• 关键词: biomedical facility; calcium channel; citrates; electrophysiology; hypercalciuria; nephrolithiasis; renal tubule

The purpose of this core is to provide support for studies on epithelial Ca 2+ channels (ECaC) and the electrogenic sodium/dicarboxylate co-transporter (NaDC-1) in components I, III, and IV. ECaC channels are present in the apical membrane of intestine and the distal convoluted tubule (DCT) of kidney and serve as gatekeepers for transcellular Ca 2+ transport in these sites. ECaC is a major target for many hormones that regulate gastrointestinal and kidney Ca 2+ absorption, such as parathyroid hormone, vitamin D, etc (1). cDNAs for ECaC and its isoforms have recently been isolated by Dr. Bindels' (2) and Dr. Hediger's groups (3, 4) independently. We have also isolated cDNA for rabbit ECaC1 and obtained cDNA for mouse ECaC2 from Dr. Bindels (consultant for this core) NaDC-1 in the proximal tubules reabsorbs filtered Krebs cycle intermediates and plays an important role in the regulation of urinary citrate concentrations (5). Low urinary citrate is an important risk factor for formation of kidney stone. In component I, we will test the hypothesis that protein product of an absorptive hypercalciuria (AH)-related gene, AH-related adenylate cyclase (AHRAC), regulates ECaC channel activity. In component III project 1, we will investigate the role of intracellular vs extracellular pH in the regulation of the electrogenic NaDC-1 (6). In component III project 2, we will test the hypothesis that acid inhibition of ECaCl-mediated Ca 2+ reabsorption in DCT contributes to the hypercalciuria induced by a high dietary protein intake and the hypothesis that membrane phospholipid, phosphatidylinositol 4,5-bisphosphate (PIP2) regulates ECaC1 channel activity. In component IV, we will test the hypothesis that down-regulation of calbindin-D28k by estrogen lack (in addition to the downregulation of ECaC) is important for renal calcium. leak and examine the molecular mechanism by which calbindin- D28k regulates Ca 2+ reabsorption through ECaC.

该核心的目的是为成分 I、III 和 IV 中的上皮 Ca 2+ 通道 (ECaC) 和电化学钠/二羧酸协同转运蛋白 (NaDC-1) 的研究提供支持。 ECaC 通道存在于肠的顶膜和肾脏的远曲小管 (DCT) 中，并在这些部位充当跨细胞 Ca 2+ 转运的看门人。 ECaC 是许多调节胃肠道和肾脏 Ca 2+ 吸收的激素的主要靶标，例如甲状旁腺激素、维生素 D 等 (1)。 Bindels 博士 (2) 和 Hediger 博士 (3, 4) 团队最近独立分离出了 ECaC 及其亚型的 cDNA。我们还分离了兔 ECaC1 的 cDNA，并从 Bindels 博士（该核心顾问）获得了小鼠 ECaC2 的 cDNA。近曲小管中的 NaDC-1 重吸收过滤的克雷布斯循环中间体，在调节尿柠檬酸盐浓度中发挥重要作用 (5 ）。尿柠檬酸水平低是肾结石形成的重要危险因素。在第一部分中，我们将检验以下假设：吸收性高钙尿症 (AH) 相关的蛋白质产物 AH 相关腺苷酸环化酶 (AHRAC) 基因调节 ECaC 通道活性。在组件中 III 项目 1，我们将研究细胞内与细胞外 pH 在调节中的作用 产电 NaDC-1 (6)。在第 III 部分项目 2 中，我们将检验以下假设：DCT 中 ECaCl 介导的 Ca 2+ 重吸收的酸抑制会导致高膳食蛋白摄入引起的高钙尿症，以及膜磷脂、磷脂酰肌醇 4,5-二磷酸 (PIP2) 的假设) 调节 ECaC1 通道活性。在第四部分中，我们将检验以下假设：雌激素缺乏导致钙结合蛋白-D28k 的下调（除了 ECaC 的下调之外）对于肾钙很重要。泄漏并检查 calbindin- D28k 调节 Ca 2+ 的分子机制 通过 ECaC 重吸收。