Mechanisms of TMJ development and long-term function

颞下颌关节发育和长期功能的机制

• 批准号: 8887326
• 负责人: EIKI KOYAMA
• 金额: $ 42万
• 依托单位: CHILDREN'S HOSP OF PHILADELPHIA
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8887326
• 关键词: Ablation; Adhesions; Age; Agonist; Apical; Area; Biology; Cells; Complex; Cues; Data; Defect; Deterioration; Development; Embryo; Erinaceidae; Failure; Fossa; Friction; Future; Gene Deletion; Genes; Health; Hyaluronic Acid; Injection of therapeutic agent; Joint Dislocation; Joints; Knockout Mice; Lead; Limb structure; Lubricants; Lubrication; Maintenance; Mastication; Mechanics; Mediating; Movement; Mus; Mutant Strains Mice; Pathway interactions; Pattern; Phenotype; Play; Production; Quality of life; Receptor Signaling; Recombinant Proteins; Recombinants; Regulation; Relative (related person); Reporter; Role; Severities; Signal Pathway; Signal Transduction; Speech; Staging; Structure; Sum; Surface; Synovial Fluid; Temporomandibular Joint; Temporomandibular Joint Disorders; Testing; Therapeutic; Therapeutic Intervention; Time; Transducers; Up-Regulation; cell type; expression vector; gain of function; human SMO protein; joint formation; joint function; loss of function; lubricin; mutant; novel; parathyroid hormone-related protein; postnatal; receptor; research study; skeletogenesis; smoothened signaling pathway; transcription factor

DESCRIPTION (provided by applicant): The temporomandibular joint (TMJ) is different from other synovial joints, in that it contains an articular disc that separates the joint space into tw synovial cavities. These distinctive features enable complex anatomical rearrangements of TMJ that take place during mastication and speech. These movements also impart shearing and frictional loads and a near dislocation of the joint. To protect joint integrity from destructive mechanical friction, superficial and disc cells produce boundary lubricants including hyaluronic acid (HA) and lubricin. Thus, deterioration of joint lubrication with age or by other insults may underlie disc adhesion and degenerative TMJ disorders. We propose to study currently poorly understood developmental aspects of TMJ biology that are critically important for TMJ functions and its long-term health. Our preliminary data showed that a secreted signaling factor, Indian hedgehog (Ihh), plays pivotal roles in TMJ development. Global Ihh ablation led to a failure of disc and synovial cavity formation, and loss of TGF-�1, PTHrP and lubricin expression. Postnatal ablation of Ihh caused markedly reduced lubricin expression and disc adhesions. These findings led to our central hypothesis that Ihh signaling is required for both TMJ formation and postnatal function. In Aim 1, the roles of Ihh signaling in TMJ development will be further defined. Initially, we will relate the spatio-temporal patterns of Ihh signaling (Gli1 activation) o the expression of hedgehog receptors, signal transducers and phenotype defining genes during TMJ development. We will then use loss and gain of function approaches to delete Smoothened or Patched1 in TMJ cells at critical developmental stages. In Aim 2, we will test the hypothesis that TGF-�1 and PTHrP mediate Ihh action on its target cells in TMJ by asking whether TGF-�1 and/or PTHrP are sufficient to rescue Ihh-null TMJ phenotype and whether conditional deletion of these genes in TMJ produce defects similar to those seen in Ihh-null mice. We will further delineate Ihh-TGF-� and Ihh- PTHrP signaling pathways and their potential interactions in the regulation of joint lubricant production and development of relevant cell types. In Aim 3, we will study the roles of joint lubricants in the Ihh- dependent postnatal TMJ maintenance. Respective roles of HA and lubricin in the protection of the TMJ will be determined by analyzing lubricin (Prg4)-null and conditional HA synthase 2 (HAS2)-deficient mice. We will also test whether TMJ defects in Ihh-null mice can be rescued by systemic or local injection of a hedgehog agonist, PTHrP/PTH, TGF-�1 or local delivery of lubricin- and/or HAS2-expression vectors. In sum, this project will provide novel, important and far-reaching information on hedgehog signaling in TMJ formation and maintenance. Our rescue experiments should provide a proof-of-principle that TMJ defects, including disc adhesions, are amenable to therapeutic intervention.

描述(申请人提供)：颞下颌关节(TMJ)不同于其他滑膜关节，因为它包含一个关节盘，将关节间隙分成两个滑膜腔。这些独特的特征使得在咀嚼和说话过程中发生的复杂的TMJ解剖重排成为可能。这些运动还会产生剪切和摩擦载荷以及关节的近乎脱位。为了保护关节完整性不受破坏性机械摩擦的影响，表浅细胞和盘状细胞产生包括透明质酸(HA)和润滑剂在内的边界润滑剂。因此，随着年龄的增长或其他原因，关节润滑性的恶化可能是导致关节盘粘连和退行性TMJ紊乱的原因。我们建议研究目前知之甚少的TMJ生物学的发育方面，这些方面对TMJ的功能和长期健康至关重要。我们的初步数据表明，一种分泌的信号因子印度刺猬(IHH)在TMJ的发育中发挥着关键作用。整体消融导致关节盘和滑膜腔形成失败，转化生长因子-�-1、甲状旁腺素受体和润滑素表达缺失。生后消融IHH导致润滑素表达和椎间盘粘连明显减少。这些发现导致了我们的中心假设，即IHH信号对TMJ的形成和出生后的功能都是必需的。在目标1中，将进一步定义IHH信号在TMJ发育中的作用。首先，我们将把IHH信号(Gli1激活)的时空模式与Hedgehog受体、信号转导和TMJ发育过程中的表型定义基因的表达联系起来。然后，我们将使用功能丧失和功能获得的方法来删除关键发育阶段的TMJ细胞中的平滑或Patched1。在目标2中，我们将通过询问转化生长因子-�1和/或甲状旁腺素rP是否足以挽救IHH缺失的TMJ表型，以及在TMJ中有条件地缺失这些基因是否会产生与IHH缺失的小鼠相似的缺陷，来验证转化生长因子-�1和甲状旁腺素rP介导的IHH作用于TMJ靶细胞的假设。我们将进一步描述IHH-转化生长因子-�和IHH-PTHrP信号通路及其在调节关节润滑剂生产和相关细胞类型发育中的潜在相互作用。在目标3中，我们将研究关节润滑剂在IHH依赖的产后TMJ维持中的作用。通过分析润滑素(Prg4)缺失和条件性HA合成酶2(HAS2)缺陷小鼠，将确定HA和润滑素在保护TMJ中的各自作用。我们还将测试是否可以通过全身或局部注射刺激剂、甲状旁腺素/甲状旁腺素、转化生长因子-�1或局部输送润滑素和/或HAS2表达载体来挽救IHH缺失小鼠的颞下颌关节缺陷。总之，该项目将为有关Hedgehog信号在TMJ形成和维持中的作用提供新的、重要的和深远的信息。我们的抢救实验应该提供一个原则证明，包括关节盘粘连在内的TMJ缺陷是可以接受治疗干预的。