DDR2, a Novel Collagen Receptor, and Mineralization

描述（由申请人提供）：纤维状I型胶原是脊椎动物中大多数矿化组织的主要框架。它在矿化中的结构作用已得到充分认识，但它作为配体控制基质组织/矿化的潜在作用基本上是未知的。盘状蛋白结构域受体2 （disidin domain receptor 2, DDR2）是一种新发现的纤维状胶原受体，存在于多种组织和器官中，但其在矿化组织中的存在和作用尚不清楚。我们的初步研究表明，DDR2在成骨细胞中高度表达，其抑制导致胶原基质组织/矿化严重影响，I型胶原和相关MMPs（即啮齿动物间质胶原酶和明胶酶）的表达改变。我们的假设是，通过成骨细胞中的DDR2信号通过调节胶原合成和降解水平来调节胶原基质的组织和矿化。为了验证这一假设，我们提出：

DESCRIPTION (provided by applicant): Fibrillar type I collagen is the major framework in most mineralized tissues in vertebrates. Its structural role in mineralization is well recognized but its potential role as a ligand to control matrix organization/mineralization is essentially unknown. Discoidin domain receptor 2 (DDR2) is a newly identified fibrillar collagen receptor found in several tissues and organs, however, its presence and roles in mineralized tissues are unknown. Our preliminary studies indicate that DDR2 is highly expressed by osteoblastic cells and that its inhibition leads to severely affected collagen matrix organization/mineralization and altered expression of type I collagen and related MMPs (i.e. rodent interstitial collagenase and gelatinase). Our hypothesis is that signaling through DDR2 in osteoblastic cells modulates collagen matrix organization and mineralization by regulating the level of collagen synthesis and degradation. To test this hypothesis, we propose: 1. To investigate the effects of lowered DDR2 expression in MC3T3-E1 cells on matrix organization and mineralization.1 a. To establish single-cell derived clones expressing lower levels of DDR2. 1b. To evaluate the mRNA expression levels of COLI and interstitial collagen-associated MMPs (MMP2, 13).1c. To characterize the content, maturation, organization and mineralization pattern of collagen matrix produced by these clones; 2. To investigate the effects of overexpression of DDR2 in MC3T3-E1 cells on matrix organization and mineralization. 2a. To establish single-cell derived clones expressing higher levels of DDR2. 2b. To evaluate the mRNA expression levels of COLI and interstitial collagen-associated MMPs (MMP2, 13). 2c. To characterize the content, maturation, organization and mineralization pattern of collagen matrix produced by these clones; 3. To investigate the activation of COLI (alpha1) and MMP2 promoters through DDR2 signaling. The results of this research would provide insights into novel regulatory roles of this newly identified collagen receptor, DDR2, in bone physiology.