Regulation of chondrocytes by extracellular matrix protein.

抽象的。F-spondin是一个蛋白质家族的成员，该家族共同属于TSR的一个亚组 （血小板反应蛋白）I型分子。我们发现F-spondin的表达与细胞凋亡显著相关。 在骨关节炎软骨以及OA的啮齿动物椎间盘切除术模型中增加。初步研究 表明F-spondin对人软骨细胞代谢具有显著影响， 胚胎生长板的肥大区域，在那里它起到调节矿化的作用， 软骨内骨形成该提议旨在表征F-脊椎蛋白的功能作用， 其对OA的进展具有重要且先前未被认识的影响。我们将测试两个 中心假设：1）F-spondin通过未识别的途径调节胶原降解，包括 TGF-β的活化和MMPs的诱导，以及2）F-spondin诱导关节软骨肥大分化 软骨细胞，并在矿化和软骨内骨的调节中发挥重要作用 阵为检验这些假设而设计的具体目标如下： 研究F-spondin对人体肥大和矿化活性的调节作用 关节软骨细胞体外培养模型。将对软骨标本进行组织学检查， 研究F-spondin与OA的其他特征性肥大/骨化标志物之间的联系 软骨细胞在特异性目的2中，我们将研究F-脊椎蛋白介导的 OA软骨中的胶原降解。外植体或细胞培养物将用于a）鉴定由F-诱导的MMP， spondin并检查它们在F-spondin介导的胶原降解中的作用B）建立TGF-β 1的作用。 c）比较全长F-spondin分子的功能活性 相对于其蛋白水解片段。在具体目标3中，我们将识别和描述相互作用 F-spondin蛋白。a）研究F-spondin与潜伏相关肽（LTP）的相互作用 和B）利用酵母2杂交和蛋白质组学技术来鉴定新的F- spondin结合蛋白（蛋白酶，受体，基质分子），可调节其在关节炎中的活性 软骨在特定目的4中，我们将研究F-spondin在软骨中的表达和功能， vivo.我们将研究F-脊椎蛋白在体内软骨中的表达i）在软骨内骨发育过程中 和ii）在OA的小鼠椎间盘切除模型中。我们将产生F-spondin敲除小鼠， 表征软骨内骨发育和OA疾病期间软骨表型的变化 进展了解F-spondin对软骨细胞功能的调节可能会导致新的 软骨修复策略和骨关节炎的疾病改善治疗。

Abstract. F-spondin is a member of a family of proteins that collectively belong to a subgroup of TSR (thrombospondin) type I class molecules. We have discovered that F-spondin expression is significantly increased in osteoarthritic cartilage as well as in rodent meniscectomy models of OA. Preliminary studies indicate that F-spondin has significant effects on human chondrocyte metabolism and is also expressed in the hypertrophic regions of embryonic growth plates where it acts to regulate mineralization and endochondral bone formation. This proposal is designed to characterize the functional effects of F-spondin, which have major and previously unrecognized implications for the progression of OA. We will test two central hypotheses: 1) F-spondin modulates collagen degradation via unrecognized pathways that include activation of TGF-¿ and induction of MMPs and 2) F-spondin induces hypertrophic differentiation of articular chondrocytes and plays an essential role in the regulation of mineralization and endochondral bone formation. The specific aims designed to test these hypotheses are as follows: In SPECIFIC AIM 1 we will investigate the effects of F-spondin on the regulation of hypertrophy and mineralizing activity in human articular chondrocytes in vitro culture models. Cartilage specimens will be examined histologically to investigate the link between F-spondin and other characteristic hypertrophic/ossification markers of OA chondrocytes. In SPECIFIC AIM 2 we will investigate the molecular mechanism(s) of F-spondin-mediated collagen degradation in OA cartilage. Explant or cell cultures will be used to a) identify MMPs induced by F- spondin and examine their role in F-spondin-mediated collagen degradation b) establish the role of TGF-¿ in modulation of F-spondin functions and c) compare functional activity of the full length F-spondin molecule relative to its proteolytic fragments. In SPECIFIC AIM 3 we will identify and characterize the interacting proteins of F-spondin. a) investigate the interaction of F-spondin with the Latency-associated peptide (LAP) of the latent TGF-¿ complex and b) utilize yeast 2 hybrid and proteomic technologies to identify novel F- spondin binding proteins (proteases, receptors, matrix molecules) that may regulate its activity in articular cartilage. In SPECIFIC AIM 4 we will investigate the expression and function of F-spondin in cartilage in vivo. We will investigate F-spondin expression in cartilage in vivo i) during endochondral bone development and ii) in the mouse meniscectomy model of OA. We will generate an F-spondin knockout mouse and characterize the changes in cartilage phenotype during endochondral bone development and OA disease progression. Understanding the regulation of chondrocyte functions by F-spondin could lead to novel strategies for cartilage repair and disease modifying treatments for osteoarthritis.