Mechanisms of Primary Cilia Regulating Tendon Enthesis Development and Regeneration

项目摘要 60岁以上的人群中有40%经历过肩袖撕裂。肩袖撕裂的高失败率 手术修复或非手术治疗后使其成为一个重大的临床挑战。失败的结局 伴随着在腱-骨附着点（肌腱附着点）处的瘢痕组织的形成， 结构和功能恶化。有效治疗方法的开发受到有限的限制， 附着点发育生物学和机械生物学的知识，以及对 支配附着点发病机制和愈合的内源性机制。为了弥合这一知识差距， 目前的建议试图阐明肌腱附着点如何响应其机械和生物化学 在发展和康复过程中的环境。众所周知，机械力和 不同的途径，包括刺猬（Hh）信号，驱动附着点的形成，促进成熟细胞的重塑， ，并影响愈合。最近，我们的研究表明，初级纤毛，一个孤立的， 触角从哺乳动物细胞表面突出，可能充当机械传导的枢纽， Hh信令。在我们以前工作的基础上，本建议的目标是获得一个机械的理解 初级纤毛在集中和同步机械和Hh信号中的作用 发展和治愈。为了实现这一目标，我们将确定纤毛附着点的身份和活动 细胞在附着点发育和机械适应（具体目标1），并评估再生 纤毛附着点细胞改善附着点愈合的能力（具体目标2）。我们将使用的方法 包括纤毛标记和纤毛缺失转基因小鼠模型、不同建立的负载模型、细胞 移植和转录组学分析，结合结构，成分和生物力学 评价测定。在这个项目的结论，我们希望确定新的纤毛调节机械， 在体内附着点机械适应的转导途径，并提出了新的机制， 纤毛将机械信号转换为细胞信号事件。初级纤毛在附着点中作用的新发现 愈合将指导新的药理学和机械生物学治疗的发展， 肩袖撕裂

PROJECT SUMMARY 40% of the population over the age of 60 experiences a rotator cuff tear. The high failure rates of rotator cuff tear after surgical repair or non-surgical treatment make it a major clinical challenge. The outcome failures accompany the formation of scar tissues at the tendon-to-bone insertion (tendon enthesis) with disorganized architecture and deteriorated function. Development of effective therapeutics has been hampered by limited knowledge of enthesis development biology and mechanobiology and an incomplete understanding of endogenous mechanisms governing enthesis pathogenesis and healing. To bridge this knowledge gap, the current proposal seeks to elucidate how tendon enthesis responds to its mechanical and biochemical environment during development and healing processes. It is known that a combination of mechanical force and distinct pathways, including hedgehog (Hh) signaling, drive enthesis formation, promote remodeling of mature enthesis, and affect enthesis healing. Recently, our studies have indicated that the primary cilium, a solitary antenna protruding from mammalian cell surface, potentially functions as a hub for mechanotransduction and Hh signaling. Building on our previous work, the objective of this proposal is to gain a mechanistic understanding of the role of primary cilia in concentrating and synchronizing mechanical and Hh signals during enthesis development and healing. To achieve this objective, we will determine identities and activities of ciliated enthesis cells during enthesis development and mechanical adaptation (Specific Aim 1) and evaluate the regenerative capacity of ciliated enthesis cells for improving enthesis healing (Specific Aim 2). The approaches we will use include cilia-labeled and cilia-deleted transgenic mouse models, different established loading models, cell transplantation, and transcriptomics analysis, combined with structural, compositional, and biomechanical evaluation assays. At the conclusion of this project, we expect to identify new cilia-regulated mechano- transduction pathways during in vivo enthesis mechanical adaptation and suggest novel mechanisms by which cilia convert mechanical cues to cellular signaling events. The new findings of the role of primary cilia in enthesis healing will guide the development of novel pharmacological and mechanobiology therapeutics for treating rotator cuff tears.