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（由申请人提供）：颞下颌关节（TMJ）与其他滑液关节不同，因为它包含将关节空间分隔成两个滑液腔的关节盘。这些独特的特征使得咀嚼和言语过程中发生的颞下颌关节复杂的解剖学重新排列成为可能。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免受破坏性机械摩擦的影响，表面细胞和椎间盘细胞会产生边界润滑剂，包括透明质酸 (HA) 和润滑素。因此，随着年龄的增长或其他损伤导致的关节润滑恶化可能是椎间盘粘连和退行性颞下颌关节紊乱的根源。我们建议研究目前人们知之甚少的颞下颌关节生物学发育方面，这些方面对于颞下颌关节功能及其长期健康至关重要。我们的初步数据表明，一种分泌的信号因子，印度刺猬 (Ihh)，在颞下颌关节发育中发挥着关键作用。整体 Ihh 消融导致椎间盘和滑膜腔形成失败，以及 TGF-β1、PTHrP 和润滑素表达丧失。产后 Ihh 消融导致润滑素表达和椎间盘粘连显着减少。这些发现得出了我们的中心假设：Ihh 信号传导对于 TMJ 形成和产后功能都是必需的。在目标 1 中，将进一步定义 Ihh 信号在 TMJ 发育中的作用。首先，我们将在 TMJ 发育过程中将 Ihh 信号传导（Gli1 激活）的时空模式与 Hedgehog 受体、信号转导器和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获得的方法来删除关键发育阶段的 TMJ 细胞中的 Smoothened 或 Patched1。在目标 2 中，我们将通过询问 TGF-β1 和/或 PTHrP 是否足以挽救 Ihh 缺失的 TMJ 表型，以及 TMJ 中这些基因的条件性删除是否会产生与 Ihh 缺失小鼠中所见的缺陷类似的缺陷，来测试 TGF-β1 和 PTHrP 介导对其在 TMJ 中的靶细胞的 Ihh 作用的假设。我们将进一步描述 Ihh-TGF-β 和 Ihh-PTHrP 信号通路及其在调节关节润滑剂产生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 依赖性产后 TMJ 维持中的作用。通过分析润滑素 (Prg4) 缺失和条件性 HA 合酶 2 (HAS2) 缺陷小鼠，可以确定 HA 和润滑素在 TMJ 保护中各自的作用。我们还将测试Ihh缺失小鼠的TMJ缺陷是否可以通过全身或局部注射hedgehog激动剂、PTHrP/PTH、TGF-β1或局部递送润滑素和/或HAS2表达载体来挽救。总之，该项目将为 TMJ 形成和维护中的刺猬信号提供新颖、重要且影响深远的信息。我们的救援实验应该提供原理证明，证明颞下颌关节缺陷（包括椎间盘粘连）适合治疗干预。