(191cu) Probing the Influence of Sibling Proteins on Collagen I Fibrillogenesis and Denaturation

Native bone tissue is comprised of a mixture of collagen, non-collagenous proteins, and hydroxyapatite (HA). Additionally, the SIBLING (small integrin binding, N-linked glycoprotein) family of proteins is the primary group of non-collagenous proteins found in mineralized tissue. The SIBLING family of proteins have all been demonstrated to contain a cell binding RGD sequence, one or more HAP or calcium binding domains, and at least one collagen binding domain. There have been extensive studies to date examining the cell binding and mineralization induction capabilities of this family of proteins, but few if any studies on the role of these proteins in collagen fibrillogenesis. In this study, the influence of six SIBLING proteins and two proteoglycan modified SIBLING proteins on both collagen fibrillogenesis and denaturation are investigated. The results suggest that dentin phosphoprotein, dentin sialoprotein, and the proteoglycan modified dentin sialoprotein have the largest impacts on the native fibrillogenesis process. When combined with the existing literature, these results provide further insight into the natural biological function of the SIBLING family of proteins during bone development.