DIRECT CALPAIN-PTH1R BINDING AFFECTS ACTIONS OF PTH/PTHrP

描述（由申请人提供）：PTH 1 R与支架蛋白的结合是甲状旁腺激素（PTH）和PTH相关肽（PTHrP）以细胞和膜特异性方式发挥作用的关键。PTH和PTHrP的受体（PTH 1 R）属于G蛋白偶联受体（GPCR）。甲状旁腺激素的主要作用是通过直接作用于骨骼和肾脏来维持钙的稳态。PTHrP是细胞生长和分化的旁分泌调节因子，其在肿瘤细胞中的异位表达与恶性肿瘤的骨转移和高钙血症有关。因此，研究PTH 1 R通过PTH和PTHrP的信号传导和生理功能对于理解疾病的机制和开发新的治疗方法至关重要。主要研究目标是研究钙蛋白酶小亚基（28 kDa亚基），一种新的相互作用，结合甲状旁腺激素1受体（PTH 1 R）对PTH和/或PTHrP介导的信号和行动的作用。具体目标1定义了钙蛋白酶介导的PTH 1 R裂解及其在PTH介导的细胞内事件中的作用。具体目标2检查钙蛋白酶作为PTH引起的下游过程的调节剂的作用。特异性目的3表征了体内具有成骨细胞特异性缺失Capn 4的小鼠和从这些小鼠分离的Capn 4缺失的成骨细胞的表型。

DESCRIPTION (provided by applicant): The PTH1R binding to scaffolding proteins is key to the actions of parathyroid hormone (PTH) and PTH-related peptide (PTHrP) in a cell- and membrane-specific manner. A receptor for PTH and PTHrP (PTH1R) belongs to G-protein coupling receptors (GPCR). PTH functions primarily to maintain calcium homeostasis through direct action on bone and kidney. PTHrP is a paracrine regulator of cellular growth and differentiation, and its ectopic expression in tumor cells is associated with bone metastasis and hypercalcemia in malignancy. Thus, to study signaling and physiological function of PTH1R via PTH and PTHrP is essential for understanding of mechanisms of diseases and developing novel therapy. The primary research goal is to investigate the role of calpain small subunits (the 28-kDa subunit), a novel interactor, binding to the parathyroid hormone 1 receptor (PTH1R) on PTH and/or PTHrP-mediated signaling and actions. Specific Aim 1 defines calpain-mediated cleavage of the PTH1R and its role on PTH-mediated intracellular events. Specific Aim 2 examines the role of calpain as a modulator of PTH-elicited downstream processes. Specific Aim 3 characterizes the phenotype of mice with osteoblast-specific deletion of Capn4 in vivo and of Capn4-null osteoblsts isolated from these mice.