EBP50 REGULATION OF PTH RECEPTOR IN BONE AND KIDNEY

该项目的长期目标是阐明甲状旁腺激素受体的细胞机制。 (PTH1R)行动。PTH1R通过作用于细胞外钙磷平衡调节细胞外钙磷平衡 肾脏和骨头。与其他G蛋白偶联受体一样，PTH1R表现出一个周期性的过程 激活、脱敏、内化和再敏化。受体脱敏提供了一种 保护细胞免受过度刺激的机制，而再敏化则保护细胞免受 长期不活动和荷尔蒙抵抗。然而，与大多数其他受体不同的是，PTH1R表现出 它的激活在细胞和组织上有相当大的差异。这些差异不能归因于 选择性剪接受体形式、受体丰度或G蛋白可获得性。最近的证据表明 胞质接头蛋白Ezrin结合蛋白50 kD(EBP50)可能与细胞特异性 PTH1R信号转导与内化。拟议研究的中心目标是检查相互作用 EBP50对PTH1R循环各个环节的调控作用。制定了四个具体的目标来测试 EBP50调节PTH1R的配体特异性反应的统一假设。目标1将 研究EBP50对细胞特异性PTH1R激活的影响。目标2将描述EBP50对 PTH1R脱敏。目标3将确定参与PTH1R的EBP50的结构决定因素 内部化。目的4将确定EBP50在PTH1R循环中的作用。计划中的研究雇用了 一系列细胞生物学、生化和分子生物学技术，将应用于特定的 肾脏和骨细胞是甲状旁腺素作用的主要靶点。初步数据提供临时数据 支持并确定大部分拟议工作的可行性。计划中的研究将产生新颖和 关于PTH1R调节细胞外钙的机制和作用的重要信息 动态平衡。这一结果将有助于更好地理解PTH1R的启动和终止 行动。这一结果可能提示导致PTH抵抗的其他病理生理机制和 带来新的治疗机会。

The long-term goal of this project is to elucidate the cellular mechanisms of parathyroid hormone receptor (PTH1R) action. The PTH1R regulates extracellular calcium and phosphate homeostasis by its actions on kidney and bone. Like other G protein-coupled receptors, the PTH1R exhibits a cyclical process of activation, desensitization, internalization, and resensitization. Receptor desensitization provides a mechanism to protect cells against excessive stimulation, while resensitization guards cells against prolonged inactivity and hormone resistance. Unlike most other receptors, however, the PTH1R exhibits considerable cell- and tissue-specific differences in its activation. These differences cannot be ascribed to alternatively spliced receptor forms, receptor abundance, or G protein availability. Recent evidence suggests that the cytoplasmic adaptor protein ezrin-binding protein 50 kD (EBP50) may contribute to cell-specific PTH1R signaling and internalization. The central goal of the proposed studies is to examine the interaction and modulatory activity of EBP50 on all aspects of PTH1R cycling. Four specific aims are developed to test the unifying hypothesis that EBP50 regulates ligand-specific responses of the PTH1R. Aim 1 will characterize the effects of EBP50 on cell-specific PTH1R activation. Aim 2 will describe EBP50 effects on PTH1R desensitization. Aim 3 will identify structural determinants of EBP50 that are involved in PTH1R internalization. Aim 4 will determine the effects of EBP50 on PTH1R recycling. The planned studies employ an array of cell biological, biochemical, and molecular biological techniques that will be applied to specific kidney and bone cells that are the primary targets of PTH action. Preliminary data provide provisional support and establish the feasibility for much of the proposed work. The planned studies will yield novel and important information on the mechanism and role by which the PTH1R regulates extracellular calcium homeostasis. The results will provide greater understanding of the initiation and termination of PTH1R action. The outcomes may suggest additional pathophysiological mechanisms causing PTH resistance and lead to new treatment opportunities.