Targeting the ubiquitin-proteasome pathway to reverse catabolic action of PTH in bone

靶向泛素-蛋白酶体途径逆转 PTH 在骨中的分解代谢作用

• 批准号: 10656316
• 负责人: Bin Wang
• 金额: $ 32万
• 依托单位: THOMAS JEFFERSON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-09-30 至 2025-06-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10656316
• 关键词: Adverse effects; Anabolic Agents; Anabolism; Arginine; Bone Formation Stimulation; Bone Marrow Cells; Bone Resorption; Bone remodeling; CRISPR/Cas technology; Calcium; Calvaria; Catabolism; Cells; Coculture Techniques; Cyclic AMP; Cyclic AMP-Dependent Protein Kinases; Data; Dissociation; Down-Regulation; Exposure to; Felis catus; GTP-Binding Protein alpha Subunits, Gs; Goals; Grant; Histologic; Homeostasis; Implant; In Vitro; Infusion procedures; Injections; Knock-out; Left; Ligands; Lysine; Mediating; Metabolic Bone Diseases; Modeling; Molecular; Mus; National Institute of Arthritis, and Musculoskeletal, and Skin Diseases; Nuclear; Oral; Osteoblasts; Osteoclasts; Osteogenesis; Osteoporosis; PTH gene; Parathyroid Hormone Receptor; Pathogenicity; Pathway interactions; Phospholipase C; Play; Production; Proteasome Inhibitor; Publishing; Receptor Activation; Receptor Down-Regulation; Receptor Signaling; Regulation; Research; Role; Safety; Signal Pathway; Signal Transduction; TNFSF11 gene; Techniques; Testing; Therapeutic; Toxic effect; Treatment Efficacy; Ubiquitin; Ubiquitination; X-Ray Computed Tomography; arm; beta catenin; bone; bone loss; bone marrow mesenchymal stem cell; bone metabolism; cost effective; desensitization; design; efficacy evaluation; extracellular; improved; in vivo; microCT; mineralization; mouse model; multicatalytic endopeptidase complex; osteoblast differentiation; pre-clinical; prevent; receptor downregulation; receptor expression; response; side effect

Project Summary/Abstract Intermittent parathyroid hormone (PTH) by daily injection increases bone formation, whereas continuous PTH causes bone resorption and limits its therapeutic value. Understanding the molecular mechanisms that promote both the beneficial anabolic PTH actions and the problematic adverse effects is critical to improving the therapeutic efficacy of PTH-based treatments. The ubiquitin-proteasome pathway plays an important role in regulating and controlling bone metabolism. The type 1 PTH receptor (PTHR) desensitizes in response to brief exposure to PTH and sustained treatment with PTH downregulates the PTHR in osteoblasts. It is unknown whether continuous PTH-caused bone loss is mediated through the ubiquitin-proteasome pathway. In studies supported by an NIAMS R03 grant, we determined that continuous PTH treatment induces PTHR ubiquitination and degradation, thereby inhibiting osteoblast differentiation and promoting osteoclast resorptive activity. In addition, PTH activates multiple signaling pathways but not all of them are anabolic. Recent data from others and our group have demonstrated that beta-catenin interacts with the PTHR carboxyl-terminal region and switches PTHR signaling from Gs/cAMP to Gq/PLC activation. Furthermore, our preliminary data show that ixazomib, a newly approved oral proteasome inhibitor with less toxicity, is able to block continuous PTH-induced PTHR proteasomal degradation and reverse PTHR signaling switch by dissociating beta-catenin from the PTHR. Based on these findings, we hypothesize that ixazomib is capable of converting the catabolic effect of continuous PTH to an anabolic effect by blocking PTHR degradation and dissociating beta-catenin. The goals of our proposed studies are to: 1) establish the proof-of-principle that inhibition of PTHR downregulation and PTHR interaction with beta-catenin renders continuous PTHR activation more effective in promoting bone formation; and 2) generate important pre-clinical data assessing the efficacy, safety, and side effects of ixazomib in our murine model of continuous PTH-mediated bone loss. Three specific aims are developed to test this hypothesis and achieve these goals, employing independent and complementary strategies. Aim 1 will detail how ixazomib rescues continuous PTH-induced PTHR catabolic signaling. In Aim 2, we will establish whether ixazomib converts continuous PTH catabolic effect to bone anabolism in vivo. Aim 3 will characterize mechanisms by which ixazomib reverses the osteocatabolic effect of continuous PTH in vitro. Successful completion of the proposed research will greatly advance our understanding of the mechanisms that promote/limit PTH effects on bone formation, and provide strong basic and preclinical data that will clarify the path to a more effective osteoporosis treatment.

项目摘要/摘要 每日注射通过间歇性甲状旁腺激素（PTH）增加骨形成，而连续的 PTH会引起骨吸收并限制其治疗价值。了解分子机制 促进有益的合成代谢PTH行动，而有问题的不利影响对于改善 基于PTH的治疗的治疗功效。泛素 - 蛋白酶体途径在 调节和控制骨代谢。 1型PTH受体（PTHR）响应于短暂的 暴露于PTH和持续治疗PTH会下调成骨细胞的PTHR。这是未知的 是否连续pTH引起的骨质流失是通过泛素 - 蛋白酶体途径介导的。在研究中 在NIAMS R03赠款的支持下，我们确定连续的PTH治疗诱导PTHR泛素化 和降解，从而抑制成骨细胞分化并促进破骨细胞的吸收活性。在 此外，PTH激活多个信号通路，但并非所有信号通路都是合成代谢的。来自其他人的最新数据 我们的小组表明，β-catenin与PTHR羧基末端区域和 开关PTHR信号从GS/CAMP到GQ/PLC激活。此外，我们的初步数据表明 Ixazomib是一种新批准的口服蛋白酶体抑制剂，毒性较小，能够阻止连续PTH诱导的 PTHR蛋白酶体降解和反向PTHR信号转换通过从PTHR中解离β-catenin来开关。 基于这些发现，我们假设Ixazomib能够转换连续的分解代谢效应 通过阻断PTHR降解和分离β-catenin，PTH达到合成代谢作用。我们的目标 拟议的研究是：1）确定抑制PTHR下调和PTHR的原则证明 与β-catenin渲染的相互作用在促进骨形成方面连续pTHR激活更有效； 2）生成重要的临床前数据，以评估ixazomib在我们的效果，安全性和副作用中 连续PTH介导的骨质流失的鼠模型。开发了三个特定目标来检验这一假设 并采用独立和互补的策略实现这些目标。 AIM 1将详细说明ixazomib的方式 营救连续PTH诱导的PTHR分解代谢信号传导。在AIM 2中，我们将确定ixazomib是否 将连续的PTH分解代谢作用转化为体内骨变成代谢。 AIM 3将通过 ixazomib在体外连续PTH的骨代谢作用逆转了。成功完成 拟议的研究将大大提高我们对促进/限制对PTH影响的机制的理解 骨骼形成，并提供强大的基本和临床前数据，以阐明更有效的路径 骨质疏松治疗。