Regulated Assembly of the Tendon Extracellular Matrix

描述（由申请人提供）：肌腱连接肌肉和骨骼，主要功能是传递和承受拉伸载荷。肌腱容易受伤，因为它们受到大的和/或重复的负载。这些损伤会导致严重的疼痛和残疾，在运动、工作环境和衰老中很常见。肌腱特异性细胞外基质组装和功能性肌腱发育的调控机制是目前应用的焦点。所获得的数据将为了解正常肌腱发育、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监管相互作用。我们以前的工作已经确定了肌腱基质组装的3个关键步骤;原纤维组装的成核;未成熟原纤维中间体的沉积和稳定以及它们进入生长阶段;以及线性和侧向原纤维生长，产生肌腱功能所需的成熟原纤维。我们假设这些步骤的调节涉及：异型V/Xi型胶原与I型胶原的相互作用;改变与FACIT胶原XII和XIV型的相互作用;以及与小的富含亮氨酸的蛋白聚糖（SLRP）的相互作用，涉及2种SLRP类，核心蛋白聚糖和双糖蛋白聚糖;以及光蛋白聚糖和纤调蛋白。具体目标是：（1）确定涉及I型和V/Xi型胶原的异型相互作用在腱原纤维组装成核中的作用;（2）鉴定（FACIT）XII和XIV型胶原在沉积到纤维中和进入原纤维生长期间稳定原纤维中间体中的功能作用;和（3）确定原纤维与SLRP的相互作用在原纤维生长步骤调节中的功能作用。将使用V/Xi型同种型表达、FACIT胶原蛋白XII和XIV型以及SLRP无效的小鼠模型。在发育过程中，将使用超微结构和形态测定方法分析具有单一或复合缺陷的小鼠。这些方法将与生物化学，免疫化学和分子分析相结合，以确定特定的功能相互作用。肌腱特异性基质组装的调控步骤的定义提供了一个基础，以进一步了解肌腱修复/再生，病理变化和这些过程的调制。

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.