骨涎蛋白促进成骨细胞分化、骨形成和骨吸收机制的研究

Bone sialoprotein (BSP) is a member of the SIBLING (Small integrin-binding of ligand, N-linked glycoprotein) family. We have discovered that BSP stimulates osteoblast differentiation and bone formation in vitro and in vivo. On the other hand, BSP also exhibits the ability to enhance bone resorption. To understand how BSP exerts these anabolic and catabolic functions through binding or formation of complexes with itself and/or other proteins, we will perform the following studies: (i) To define the cellular levels during osteoblast /osteoclast differentiation induced by BSP using cell cultures of an osteoblast precursor cell line, MC3T3E1 and a pluripotent cell line, C3H10T1/2 in combination with the in vivo models of rat calvarial defect and subcutaneous implantation/an osteoclast precursor cell line, RAW 264.7, primary preosteoblasts and their progenitors, respectively; (ii) To determine the effects of the BSP posttranslational modifications such as phosphorylation and glycosylation,its ArgGlyAsp cell-binding sequence and non-RGD region on biological behaviors of the cells and bone formation and resorption; (iii) To examine the effects of interaction of BSP and its products with bone major components, type I collagen and hydroxyapatite, on osteoblast and osteoclast differentiation and bone formation and resorption; (iv) To identify BSP interaction 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 osteoblast and osteoclast differentiation, bone formation and resorption and their coupling, provide important new insights into the prevention and treatment of bone and teeth diseases such as bone defects due to trauma and tumors, osteoporosis, osteopetrosis, Paget's disease, osteogenesis imperfect, periodontal disease, etc.

骨涎蛋白（Bone sialoprotein，BSP）是SIBLING家族成员。我们发现BSP在体外和体内都能促进成骨细胞分化和骨形成。另一方面，BSP也具有促进骨吸收的能力。为了了解BSP如何与自己和/或其它蛋白质发生相互作用而发挥两面性功能，我们将进行如下的研究：(i)通过细胞培养和动物实验明确BSP作用于成骨细胞和破骨细胞分化过程的具体阶段；(ii)确定BSP的磷酸化、糖基化和ArgGlyAsp序列对成骨细胞分化和骨形成和吸收的作用；(iii)分析BSP和其不同构体与骨的主要成分,I型胶原和羟基磷灰石的相互作用对细胞分化和骨形成和吸收的影响；(iv)利用质谱鉴定与BSP相互作用的包括受体的蛋白质。本研究成果将增加对骨形成、骨吸收以及两者之间的耦联机制的了解，对骨和牙疾病如外伤或肿瘤引起的骨缺损、骨质疏松、骨硬化病、Paget骨病、成骨不全症和牙周病等的预防和治疗提供重要的新见解。