REGULATION OF COLLAGEN MATRIX MINERALIZATION

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DESCRIPTION (provided by applicant): The long-term goal of this study is to understand the regulatory mechanisms of collagen matrix mineralization in bones and teeth. During the last grant period, we have partially characterized the unique aspects of collagen cross-linking, and specific tissue distribution as well as mRNA expression pattern of collagen-binding small leucine-rich proteoglycans (CB-SLRPs) in mineralized tissues. These and other findings have led us to hypothesize: 1. the covalent intermolecular cross-linking of type I collagen is involved in regulating the spatial aspect of mineralization, and 2. a collagen-binding proteoglycan, decorin (DCN), partially regulates the timing and quality of collagen mineralization. To test these hypotheses, we would like: 1a. To establish osteoblastic cell clones that synthesize low levels of lysyl hydroxylase-2 to switch the cross-linking pathway from mineralized to non-mineralized tissue phenotype, 1b. To characterize the lysine hydroxylation and cross-linking chemistries (type, quantity and molecular distribution) of collagen matrix, and the mineralization pattern produced by the clones in vitro and in vivo. 2a. To investigate the roles of DCN in collagen maturation and mineralization in vitro and in vivo by employing overexpression and antisense approaches in osteoblastic cell line. 2b. To characterize the matrix mineralization (collagen and mineral) in bones/dentin in DCN-deficient and DCN/biglycan-double deficient mice. 2c. To evaluate the effects of DCN-collagen interaction on collagen maturation in vitro. The data obtained from this study may provide insights into the regulatory mechanisms of collagen mineralization in bones and teeth.