Regulated Assembly of the Tendon Extracellular Matrix

描述（由申请人提供）：肌腱连接肌肉和骨骼，具有传递和承受拉伸载荷的主要功能。肌腱容易受伤，因为它们受到大的和/或重复负荷。这些伤害会造成严重的疼痛和残疾，在运动、工作环境和老年人中很常见。参与肌腱特异性细胞外基质组装和功能性肌腱发育的调节机制是当前应用的重点。获得的数据将为理解正常肌腱的发育、生长、成熟以及与衰老、损伤和修复相关的变化提供重要参数。我们的一般假设是肌腱基质组装是一个多步骤的过程，每一步都需要特定的调节相互作用。我们之前的工作已经确定了肌腱基质组装的3个关键步骤；纤维组合体成核；未成熟纤维中间体的沉积和稳定以及它们进入生长阶段；以及线状和横向纤维生长，产生肌腱功能所需的成熟原纤维。我们假设这些步骤的调控涉及：异型V/XI型胶原与I型胶原的相互作用；改变与FACIT XII和XIV型胶原蛋白的相互作用；与富含亮氨酸的小蛋白聚糖（SLRP）的相互作用，包括2类SLRP， decorin和biglycan；还有荧光蛋白和纤维调节蛋白。具体目的是：(1)确定涉及I型和V/XI型胶原的异型相互作用在肌腱原纤维组装成核中的作用；(2)鉴定（FACIT） XII型和XIV型胶原在纤维中间体沉积和进入纤维生长过程中的稳定作用；(3)确定纤维与slrp相互作用在调节纤维生长步骤中的功能作用。将使用无v /XI型异构体表达的小鼠模型，FACIT XII和XIV型胶原以及slrp。单一或复合缺陷小鼠将在发育过程中使用超微结构和形态计量学方法进行分析。这些方法将与生化、免疫化学和分子分析相结合，以确定特定的功能相互作用。定义肌腱特异性基质组装的调控步骤为我们进一步理解肌腱修复/再生、病理变化和这些过程的调节提供了基础。

DESCRIPTION (provided by applicant): Tendons connect muscle to bone and have a primary function in transmitting and withstanding tensile loads. Tendons are prone to injury because they are subjected to large and/or repetitive loads. These injuries cause significant pain as well as disability and are common in sports, work environments and aging. The regulatory mechanisms involved in tendon-specific extracellular matrix assembly and development of a functional tendon are the focus of the current application. The data obtained will provide important parameters for understanding normal tendon development, growth, maturation as well as changes associated with aging, injury and repair. Our general hypothesis is that tendon matrix assembly is a multi-step process, with each step requiring specific regulatory interactions. Our previous work has identified 3 key steps in tendon matrix assembly; nucleation of fibril assembly; deposition and stabilization of immature fibril intermediates as well as their entrance into the growth phase; and linear and lateral fibril growth, generating the mature fibrils required for tendon function. We hypothesize that the regulation of these steps involve: heterotypic type V/XI collagen interactions with type I collagen; changing interactions with FACIT collagen types XII and XIV; and interactions with small leucine-rich proteoglycans (SLRPs) involving 2 SLRP classes, decorin and biglycan; and lumican and fibromodulin. The specific aims are to: (1) determine the role(s) of heterotypic interactions involving collagens type I and type V/XI in nucleation of tendon fibril assembly; (2) identify the functional roles of (FACIT) collagen types XII and XIV in stabilization of fibril intermediates during deposition into fibers and entrance into fibril growth; and (3) determine the functional roles of fibril interactions with SLRPs in the regulation of fibril growth steps. Mouse models null for typeV/XI isoform expression, FACIT collagen types XII and XIV and SLRPs will be utilized. Mice with single or compound deficiencies will be analyzed during development using ultrastructural and morphometric approaches. These approaches will be integrated with biochemical, immunochemical and molecular analyses to define specific functional interactions. Definition of the regulatory steps in tendon-specific matrix assembly provides a foundation to further our understanding of tendon repair/regeneration, pathological changes and the modulation of these processes.