Regulation of PTH secretion by TRPC1

TRPC1 对 PTH 分泌的调节

• 批准号: 9902425
• 负责人: Wenhan Chang
• 金额: $ 50.67万
• 依托单位: UNIVERSITY OF OKLAHOMA HLTH SCIENCES CTR
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-04-01 至 2023-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9902425
• 关键词: Adaptor Signaling Protein; Address; Affect; Aging; Area; Biochemical; Biochemistry; Biological; Biological Assay; Biophysics; Calcium-Sensing Receptors; Cardiovascular system; Cell Surface Receptors; Cells; Cellular biology; Clathrin Adaptors; Complex; Data; Disease of parathyroid glands; Endocrine Glands; Endocrine System Diseases; Familial hypocalciuric hypercalcemia; Forteo; GTP-Binding Protein alpha Subunits; Gene Deletion; Genes; Genetic; Genetic Diseases; Homeostasis; Hormonal; Hormone secretion; Human; Hypercalcemia; Hyperparathyroidism; Hyperplasia; In Vitro; Ion Channel; Kidney; Kidney Diseases; Knockout Mice; Knowledge; Lead; Link; Mediating; Mediator of activation protein; Minerals; Molecular; Morbidity - disease rate; Mus; Mutation; Organ; Osteoporosis; PTH gene; Parathyroid Adenoma; Parathyroid gland; Pathogenicity; Pathway interactions; Patients; Phenotype; Physiological; Physiology; Population; Receptor Signaling; Recycling; Regulation; Resistance; Role; Secondary Hyperparathyroidism; Secondary to; Sigma Factor; Signal Pathway; Signal Transduction; Testing; Time; Treatment Efficacy; base; bone; bone loss; bone mass; calcium excretion; design; enhancer-binding protein AP-2; experimental study; extracellular; genetic approach; guanine nucleotide binding protein; human disease; in vivo; insight; knockout gene; multidisciplinary; novel therapeutics; receptor; response; skeletal; urinary

Primary hyperparathyroidism is the one of the most common endocrine disorders. Primary hyperparathyroidism results from parathyroid adenomas while secondary hyperparathyroidism results from parathyroid gland hyperplasia in the setting of renal disease. Both conditions are associated with decreased expression of the Ca2+ sensing receptor (CaSR) which is required to suppress parathyroid hormone (PTH) secretion in the setting of hypercalcemia. Understanding the molecular mechanisms that regulate PTH secretion downstream of CaSR is critical for the discovery of new therapeutics to treat hyperparathyroidism and its associated morbidity. Here we show for the first time that Tprc1-null mice develop primary hyperparathyroidism, hypercalcemia, and low urinary calcium excretion mimicking the human disease Familial Hypocalciuric Hypercalcemia (FHH). FHH is a form of primary hypeparathyroidism and caused by inactivating mutations in CASR, GNA11 and AP2S1 encoding CaSR, the α11 subunit of the guanine nucleotide-binding protein, and the σ1 subunit of the AP2 clathrin-associated adaptor complex mediating recycling of cell surface receptors and channels, respectively. Thus, we tested whether TRCP1 function is directly linked to CaSR signaling. Biochemical, functional, and cell biological experiments in vitro show that TRPC1 is activated by CaSR involving the action of Gα11. We also show that TRPC1 physically interacts with AP2σ1. These data lead us to the hypothesis that TRPC1 is required for normal suppression of PTH secretion in the parathyroid gland by acting downstream of CaSR via Gα11. The interaction of TRPC1 with AP2σ1 increases the availability of TRPC1 for CaSR-induced signaling by accelerating recycling of inactivated TRPC1. In Aim 1, we will employ cell biological approaches to define the mechanism by which TRPC1 mediates CaSR-induced Ca2+ signaling and the role of Gα11 and AP2σ1 in this signaling pathway in cells derived from the parathyroid gland. In specific Aim 2, we will determine whether TRPC1 functions downstream of CaSR and Gα11 in vivo, by asking whether compound mice lacking Trpc1 and Casr or Gnα11/Gnαq genes in their parathyroid glands show more severe FHH-like phenotypes than phenotypes elicited by single gene deletions. Understanding the pathways that regulate PTH secretion could have a high impact on designing new and more effective and specific approaches to treat patients with primary as well as secondary hyperparathyroidism.

原发性甲状旁腺功能亢进是最常见的内分泌疾病之一。基本的 甲状旁腺功能亢进症是甲状旁腺腺瘤引起的 在肾脏疾病的情况下，甲状旁腺增生。两种条件都与改善有关 抑制甲状旁腺激素（PTH）所需的Ca2+灵敏度接收器（CASR）的表达 在高钙血症的情况下分泌。了解调节PTH的分子机制 CASR下游的分泌对于发现新疗法以治疗甲状旁腺功能亢进至关重要 及其相关的发病率。在这里，我们首次展示了TPRC1-NULL小鼠开发主要 甲状旁腺功能亢进，高钙血症和低尿钙排泄模仿人类疾病家族 低钙高钙血症（FHH）。 FHH是主要甲状旁腺功能亢进的一种形式，是由于失活而引起的 CASR，GNA11和AP2S1的突变编码CASR，鸟嘌呤核结合的α11亚基 蛋白质，AP2网格蛋白相关的衔接子复合物的σ1亚基介导细胞表面的回收 接收器和频道。那就是我们测试了TRCP1功能是否直接链接到CASR 信号。体外的生化，功能和细胞生物学实验表明，TRPC1被激活 CASR涉及Gα11的作用。我们还表明TRPC1与AP2σ1物理相互作用。这些数据 导致我们假设TRPC1是甲状旁腺中正常抑制PTH分泌所必需的 通过通过Gα11作用CASR的下游作用腺。 TRPC1与AP2σ1的相互作用增加了 通过加速灭活TRPC1的回收，TRPC1可用于CASR诱导的信号传导。在AIM 1中，我们 将采用细胞生物学方法来定义TRPC1介导CASR诱导的Ca2+的机制 信号传导以及Gα11和AP2σ1在源自甲状旁腺的细胞中该信号传导途径中的作用。 在特定的目标2中，我们将确定casr和gα11在体内的下游功能是否函数 询问其甲状旁腺中缺乏TRPC1和CASR或Gnα1基因的复合小鼠是否存在 与单个基因缺失引起的表型相比，显示出更严重的FHH样表型。了解 调节PTH分泌的途径可能会对设计新的，更有效的影响产生很大的影响，并且 治疗原发性和继发性甲状旁腺功能亢进的患者的特定方法。