骨涎蛋白调控软骨细胞增殖及分化的机制研究

We have showed that Bone sialoprotein (BSP) promotes osteoblast proliferation and differentiation in vitro and in vivo. Analyses of BSP-knockout mice reveal stage-dependent changes of cartilage formation. Therefore, we hypothesize that BSP regulates the chondrocyte proliferation and differentiation. To examine this hypothesis, we will perform the following studies: (a) To define the stages of chondrocyte proliferation and differentiation regulated by BSP using cell cultures of chondrogenic ATDC5 and pluripotent C3H10T1/2 cell lines; (b) To determine the effects of the BSP posttranslational modifications such as phosphorylation and glycosylation, its ArgGlyAsp cell-binding sequence and non-RGD regions on the proliferation and differentiation in the cells; (c) To examine the effects of interaction of BSP and ts products with cartilage major extracellular matrix component, type II collagen on the proliferation and differentiation in the cells in combination with the in vivo models of rat osteochondral defects; (iv) To identify BSP interacting proteins including its receptors via cell cultures, chemical crosslinking and affinity purification followed by mass spectrometric analyses. The outcomes of these studies will increase understanding of the mechanisms of endochondral ossification and cartilage formation, provide important new insights into cartilage repair and regeneration.

我们发现骨涎蛋白(Bone sialoprotein, BSP)在体内和体外促进成骨细胞增殖和分化。BSP基因敲除导致发育阶段依存性的软骨形成变化。因此，我们假设BSP调控软骨细胞增殖及分化。为了验证这假说，我们将进行如下研究：(a) 通过细胞培养，明确BSP作用于软骨细胞增殖分化过程的具体阶段； (b) 确定BSP翻译后修饰磷酸化和糖基化、RGD序列和非RGD序列在BSP调控软骨细胞增殖与分化中的作用；(c) 通过体外和体内实验，分析BSP及其不同构体与软骨细胞外基质主要成分II型胶原的相互作用对软骨细胞增殖与分化的影响；(d) 利用质谱鉴定与BSP相互作用的细胞外基质蛋白、细胞表面分子以及相关的细胞内分子。本研究结果将加深对软骨内骨化及软骨形成机制的理解，为外伤等引起的软骨缺损修复与再生、骨关节炎的治疗等提供重要依据。