Targeting the PTH1R Signaling Pathway for Osteoarthritis Therapy by a Novel Disruptor Peptide

项目概要/摘要 该项目的长期目标是设计具有成本效益、毒性较小、使用方便的合成代谢药物。 用于治疗骨关节炎（OA）。目前的 OA 治疗方法对预防效果有限 和软骨退化的进展。软骨中复杂的信号传导事件是 OA 发病机制的基础 这些都是可以有针对性的。甲状旁腺激素 (PTH) 与甲状旁腺激素相关蛋白 (PTHrP) 结合 与 I 型 PTH/PTHrP 受体 (PTH1R) 结合，引发 Gs/cAMP 和 Gq/PLC 信号通路。已发表 以及我们的初步数据证明 PTH1R Gs/cAMP 信号臂具有治疗作用和 Gq/PLC 信号臂是致病性的。 β-连环蛋白介导经典 Wnt 信号传导，促进 软骨细胞肥大分化并在 OA 发展中起重要作用。然而， PTH1R 和 β-连环蛋白之间导致 OA 发病机制的相互作用仍知之甚少。 其他人和我们小组的最新数据表明，β-连环蛋白与 PTH1R 相互作用， 将 PTH1R 信号从 Gs/cAMP 激活切换为 Gq/PLC 激活。此外，β-连环蛋白的表达 人类 OA 增加，其结果促进 PTH1R 信号传导开关并导致关节 软骨损失和 OA 发展。已确定全身或关节内给药 PTH或PTHrP能够防止软骨退化并使受损的软骨再生。然而，每天 注射 PTH 或 PTHrP 不方便且会降低用药依从性。 PTHrP 通常由 软骨细胞水平较低，并且在 OA 中增加。六个氨基酸的羧基末端区域是β- PTH1R 中的连环蛋白结合位点。我们的初步研究确定，这种六氨基酸肽 （干扰肽）阻断 β-连环蛋白与 PTH1R 的结合。基于这些发现，我们假设 干扰肽使内源性 PTHrP 诱导的 PTH1R 信号转导偏向于治疗性信号转导臂 提高PTHrP抑制软骨退变、治疗/预防OA的能力。三个具体目标是 建议检验这一假设。目标 1 将开发一种优异的干扰肽 (SDP)，以有效阻断 β-连环蛋白与 PTH1R 相互作用并抑制 β-连环蛋白介导的 PTH1R 信号转导开关。瞄准 2、我们将确定表达SDP的腺相关病毒是否可以预防软骨损伤以及 增加小鼠 OA 模型中的软骨修复。目标 3 将描述 SDP 所采用的机制 调节 PTHrP 对软骨细胞肥大分化和软骨细胞分解代谢的影响。成功 因此，完成这些研究构成了重要的临床前发现，将有助于 这项工作朝着 OA 的临床试验和最终在人类中的应用迈进。

Project Summary/Abstract The long-term goal of this project is to design cost-effective anabolic agents with less toxicity, and convenient use for the treatment of osteoarthritis (OA). Current treatments of OA have limited effects on the prevention and progression of cartilage degeneration. Complex signaling events in cartilage underlie OA pathogenesis and these can be targeted. Parathyroid hormone (PTH) and parathyroid hormone-related protein (PTHrP) bind to the type I PTH/PTHrP receptor (PTH1R) to elicit both Gs/cAMP and Gq/PLC signaling pathways. Published as well as our preliminary data demonstrate a PTH1R Gs/cAMP signaling arm that is therapeutic and a Gq/PLC signaling arm that is pathogenic. Beta-catenin mediates canonical Wnt signaling, facilitates chondrocyte hypertrophic differentiation and plays an important role in OA development. However, the interplay between PTH1R and beta-catenin that contributes to OA pathogenesis remains poorly understood. Recent data from others and our group have demonstrated that beta-catenin interacts with the PTH1R and switches PTH1R signaling from Gs/cAMP to Gq/PLC activation. Moreover, beta-catenin expression is increased in human OA, the outcome of which promotes the PTH1R signaling switch and causes articular cartilage loss and OA development. It has been established that systemic or intra-articular administration of PTH or PTHrP is able to prevent cartilage degeneration and regenerate the damaged cartilage. However, daily injection of PTH or PTHrP is inconvenient and reduces medication adherence. PTHrP is normally secreted by chondrocytes in low levels and is increased in OA. The carboxyl-terminal region of six amino acids is the beta- catenin binding site in PTH1R. Our preliminary studies have determined that this six-amino-acid peptide (disruptor peptide) blocks beta-catenin binding to PTH1R. Based on these findings, we hypothesize that the disruptor peptide biases endogenous PTHrP-induced PTH1R signaling to favor the therapeutic signaling arm and improve the ability of PTHrP to inhibit cartilage degeneration and treat/prevent OA. Three specific aims are proposed to test this hypothesis. Aim 1 will develop a superior disruptor peptide (SDP) to efficiently block the interaction of beta-catenin with PTH1R and inhibit the beta-catenin-mediated PTH1R signaling switch. In Aim 2, we will establish whether the adeno-associated virus expressing SDP prevents cartilage lesions and increase cartilage repair in a mouse OA model. Aim 3 will characterize mechanisms by which the SDP regulates PTHrP effects on chondrocyte hypertrophic differentiation and chondrocyte catabolism. Successful completion of these studies therefore constitutes important preclinical findings that would facilitate advancement of this work toward clinical trials of OA, and ultimate application in humans.