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

基本信息

批准号：
10266824
负责人：
Bin Wang
金额：
$ 32.42万
依托单位：
THOMAS JEFFERSON UNIVERSITY
依托单位国家：
美国
项目类别：
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/10266824
关键词：
Adverse effects Anabolic Agents Anabolism Arginine Bone Marrow Cells Bone Resorption Bone remodeling CRISPR/Cas technology Calcium Calvaria Catabolism Cells Clinical Data Coculture Techniques Cyclic AMP Cyclic AMP-Dependent Protein Kinases Data Down-Regulation Exposure to 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 Phospholipase C Play Production Proteasome Inhibitor Publishing Receptor Activation Receptor Signaling Regulation Research Role Safety Scanning Signal Pathway Signal Transduction Techniques Testing Therapeutic Toxic effect Treatment Efficacy Ubiquitin Ubiquitin-Proteasomal Pathway Ubiquitination arm base beta catenin bone bone loss bone marrow mesenchymal stem cell bone metabolism cost effective desensitization design extracellular improved in vivo microCT mineralization mouse model multicatalytic endopeptidase complex osteoblast differentiation pre-clinical prevent receptor receptor downregulation receptor expression response side effect

项目摘要

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.

项目概要/摘要每日注射间歇性甲状旁腺激素（PTH）可增加骨形成，而连续注射则可促进骨形成。 PTH 会导致骨吸收并限制其治疗价值。了解其分子机制促进有益的合成代谢 PTH 作用和有问题的副作用对于改善 PTH 至关重要基于 PTH 的治疗的疗效。泛素-蛋白酶体途径在调节和控制骨代谢。 1 型 PTH 受体 (PTHR) 对短暂的反应脱敏暴露于 PTH 和持续治疗 PTH 会下调成骨细胞中的 PTHR。未知 PTH 引起的持续骨质流失是否是通过泛素-蛋白酶体途径介导的。在研究中在 NIAMS R03 资助的支持下，我们确定持续 PTH 治疗会诱导 PTHR 泛素化和降解，从而抑制成骨细胞分化并促进破骨细胞再吸收活性。在此外，PTH 激活多种信号传导途径，但并非所有信号传导途径都是合成代谢的。其他人的最新数据我们的小组已经证明 β-连环蛋白与 PTHR 羧基末端区域相互作用将 PTHR 信号从 Gs/cAMP 激活切换为 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，能够阻断持续的PTH诱导通过将 β-连环蛋白从 PTHR 解离来降解 PTHR 蛋白酶体并逆转 PTHR 信号转导。基于这些发现，我们假设伊沙佐米能够转化连续药物的分解代谢作用 PTH 通过阻止 PTHR 降解和解离 β-连环蛋白来发挥合成代谢作用。我们的目标拟议的研究目的是：1）建立原理验证，即抑制 PTHR 下调和 PTHR 与 β-连环蛋白相互作用，使持续的 PTHR 激活更有效地促进骨形成； 2) 生成重要的临床前数据，评估伊沙佐米在我们的研究中的功效、安全性和副作用持续 PTH 介导的骨质流失的小鼠模型。制定了三个具体目标来检验这一假设并采用独立和互补的策略来实现这些目标。目标 1 将详细说明 ixazomib 如何拯救持续的 PTH 诱导的 PTHR 分解代谢信号。在目标 2 中，我们将确定 ixazomib 是否将持续的 PTH 分解代谢作用转化为体内骨合成代谢。目标 3 将通过以下方式描述机制特征：其中 ixazomib 在体外可逆转持续 PTH 的骨分解代谢作用。圆满完成了拟议的研究将极大地增进我们对促进/限制 PTH 影响的机制的理解骨形成，并提供强有力的基础和临床前数据，这将阐明更有效的途径骨质疏松症治疗。