Novel Regulation of PTH Receptor Functions in Bone

骨中 PTH 受体功能的新调控

• 批准号: 8510884
• 负责人: Bin Wang
• 金额: $ 7.63万
• 依托单位: UNIVERSITY OF PITTSBURGH AT PITTSBURGH
• 依托单位国家: 美国
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-04-01 至 2014-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8510884
• 关键词: Adenylate Cyclase; Anabolism; Animals; Binding; Bone Density; Bone Resorption; Bone remodeling; Cells; Clinical; Co-Immunoprecipitations; Continuous Infusion; Cyclic AMP; Data; Disease; Down-Regulation; End stage renal failure; Exposure to; Functional disorder; G-Protein-Coupled Receptors; Goals; Herpes zoster disease; Homeostasis; Hyperparathyroidism; Knockout Mice; Knowledge; Ligands; Measures; Mediating; Minerals; Mus; Opiates; Opioid Receptor; Osteoblasts; Osteogenesis; Osteoporosis; PDZ protein; PTEN protein; Parathyroid Hormone Receptor; Pathway interactions; Patients; Phospholipase C; Phosphotransferases; Proteins; Proteomics; Proto-Oncogene Proteins c-akt; Receptor Down-Regulation; Recycling; Regulation; Renal Osteodystrophy; Research; Resistance; Role; Scaffolding Protein; Scanning; Secondary Hyperparathyroidism; Signal Pathway; Signal Transduction; Techniques; Testing; Therapeutic; Therapeutic Effect; Wild Type Mouse; base; bone; bone loss; bone mass; bone metabolism; design; human RGS2 protein; human RIPK1 protein; insight; knock-down; member; membrane-associated guanylate kinase; novel; parathyroid hormone (1-34); presynaptic density protein 95; public health relevance; receptor; receptor function; research study; response; skeletal; small hairpin RNA; spinophilin; tomography; trafficking

DESCRIPTION (provided by applicant): The type 1 parathyroid hormone receptor (PTH1R), a member of G-protein coupled receptors (GPCRs), mediates PTH actions to maintain bone mineral homeostasis. Osteoblast dysfunction leading to bone loss is thought to be a key mechanism in osteoporosis. Intermittent administration of PTH (1-34) stimulates bone formation in patients and in experimental animals. Continuous infusion of PTH (1-34), which mimics pathological changes in clinical hyperparathyroidism, causes bone resorption. Patient with end-stage renal disease develops a systemic disorder of mineral and bone metabolism, such as renal osteodystrophy. PTH1R down-regulation and skeletal resistance to PTH not only reduce the therapeutic effect of PTH treatment for osteoporosis, but also occur in diseases including secondary hyperparathyroidism and renal osteodystrophy. To protect against the PTH1R down-regulation is a complementary strategy that may be useful for treatment of these diseases. Although the signaling pathways of PTH receptor are reasonably well understood, the mechanism of regulation of PTH1R functions remains to be characterized. Postsynaptic density 95/discs large/zona occludens (PDZ) scaffolding proteins comprise a key class of GPCRs-interacting proteins that can strongly influence signaling and trafficking of GPCRs. We identified two novel PTH1R associating proteins by using a newly developed proteomic array of distinct PDZ domains and coimmunoprecipitation experiments. These PDZ scaffolding proteins, MAGI-3 and spinophilin, are endogenously expressed in osteoblasts. Both MAGI-3 and spinophilin increase PTH-induced cAMP formation in osteoblasts. Based on these observations, we hypothesize that MAGI-3 and spinophilin modulate PTH1R functions and protect against receptor down-regulation in bone. Three specific aims are developed to test this hypothesis. Aim 1 will determine the effects of MAGI-3 and spinophilin on PTH1R signaling in osteoblasts. In Aim 2, we will identify whether MAGI-3 and spinophilin protect against PTH1R down-regulation in osteoblasts. Aim 3 will define the role of spinophilin on bone formation bone resorption in mice treated with intermittent PTH. Successful completion of the proposed studies will provide novel and important information on the regulation of PTH1R signaling, trafficking, and functions by MAGI-3 and spinophilin in bone. The knowledge gained from these studies will provide important insight into therapeutics for the treatment of osteoporosis and other diseases related to PTH1R down-regulation such as secondary hyperparathyroidism and renal osteodystrophy.

描述(申请人提供)：1型甲状旁腺激素受体(PTH1R)，是G蛋白偶联受体(GPCRs)的成员，介导甲状旁腺激素(PTH)作用，维持骨矿物质平衡。成骨细胞功能障碍导致骨丢失被认为是骨质疏松症的关键机制。间歇给药甲状旁腺素(1-34)可刺激患者和实验动物的骨形成。持续输注甲状旁腺素(1-34)，模拟临床甲状旁腺功能亢进症的病理变化，导致骨吸收。终末期肾病患者出现全身性矿物质和骨代谢紊乱，如肾性骨营养不良。PTH1R下调和骨骼对PTH的抵抗不仅降低了PTH治疗骨质疏松症的疗效，而且在继发性甲状旁腺功能亢进和肾性骨营养不良等疾病中也会发生。防止PTH1R下调是一种辅助策略，可能对这些疾病的治疗有用。虽然甲状旁腺素受体的信号通路已经被很好地理解，但甲状旁腺素受体功能的调节机制仍有待研究。突触后密度95/视盘大/小带闭塞(PDZ)支架蛋白是一类关键的GPCRs相互作用蛋白，可以强烈影响GPCRs的信号和运输。我们通过新开发的不同PDZ结构域的蛋白质组阵列和免疫共沉淀实验鉴定了两个新的PTH1R结合蛋白。这些PDZ支架蛋白MAGI-3和刺亲素在成骨细胞中内源性表达。MAGI-3和SPIN均可增加甲状旁腺素诱导的成骨细胞内cAMP的生成。基于这些观察，我们假设MAGI-3和亲刺素调节PTH1R的功能，并保护骨骼中的受体下调。为了检验这一假说，我们制定了三个具体目标。目的1研究MAGI-3和刺激素对成骨细胞PTH1R信号转导的影响。在目标2中，我们将确定MAGI-3和亲刺素是否能保护成骨细胞中PTH1R的下调。目的3确定亲刺素在间歇性甲状旁腺激素治疗的小鼠骨形成和骨吸收中的作用。这些研究的成功完成将为调节PTH1R信号、运输以及MAGI-3和刺亲素在骨骼中的功能提供新的和重要的信息。从这些研究中获得的知识将为治疗骨质疏松症和其他与PTH1R下调相关的疾病，如继发性甲状旁腺功能亢进和肾性骨营养不良提供重要的见解。