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

项目摘要/摘要 该项目的长期目标是设计出毒性小、使用方便、经济实惠的合成代谢制剂。 用于治疗骨关节炎(OA)。目前对骨性关节炎的治疗在预防方面效果有限。 和软骨退变的进展。软骨中复杂的信号事件是骨性关节炎发病的基础 而这些都可以成为目标。甲状旁腺激素和甲状旁腺激素相关蛋白结合 与I型PTH/PTHrP受体(PTH1R)结合，诱导Gs/cAMP和GQ/PLC信号通路。已出版 以及我们的初步数据表明，PTH1RGs/cAMP信号臂具有治疗性和 GQ/PLC信号臂是致病的。β-连环蛋白介导规范的Wnt信号，促进 软骨细胞的肥大分化在骨性关节炎的发生发展中起重要作用。然而， PTH1R和β-连环蛋白之间的相互作用在OA发病机制中的作用仍然知之甚少。 其他人和我们团队的最新数据表明，β-连环蛋白与PTH1R和PTH1R相互作用 将PTH1R信号从Gs/cAMP切换到GQ/PLC激活。此外，β-连环蛋白的表达是 在人类骨性关节炎中增加，其结果促进PTH1R信号开关并导致关节 软骨丢失与骨性关节炎的发生。已经证实，全身或关节内给药 甲状旁腺激素或甲状旁腺素可防止软骨退变，使受损软骨再生。然而，每天 注射甲状旁腺素或甲状旁腺素不方便，会降低药物依从性。甲状旁腺素受体通常由 软骨细胞低表达，在骨性关节炎中增多。六种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了这个由六个氨基酸组成的多肽 (干扰肽)阻断β-连环蛋白与PTH1R的结合。根据这些发现，我们假设 干扰素使内源性PTHrP诱导的PTH1R信号偏向于治疗信号臂 提高甲状旁腺激素抑制软骨退变、治疗/预防骨性关节炎的能力。三个具体目标是 提出用来检验这一假说。目标1将开发一种高级干扰素(SDP)，以有效地阻断 β-连环蛋白与PTH1R的相互作用并抑制β-连环蛋白介导的PTH1R信号转导。在AIM 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和 促进小鼠骨性关节炎模型的软骨修复。目标3将描述SDP通过哪些机制 调节甲状旁腺素对软骨细胞肥大分化和分解代谢的影响。成功 因此，这些研究的完成构成了重要的临床前发现，将有助于 这项工作的进展是骨性关节炎的临床试验，并最终应用于人类。

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.