Sibling proteins and their influence on collagen-i fibrillogenesis and denaturation

Abstract

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT REQUEST OF AUTHOR.] Native bone tissue is comprised of a mixture of collagen, non-collagenous proteins, and hydroxyapatite (HA). The SIBLING (small integrin binding, N-linked glycoprotein) family of proteins is the primary group of non-collagenous proteins found in bone tissue, several of which have been identified ahead of the mineralized front of developing bone. It is believed that the native bone tissue can be developed as a scaffold in vitro. In this work, bone sialoprotein (BSP), osteopontin (OPN), dentin sialoprotein (DSP), dentin phosphoprotein (DPP), C-terminal fragment of dentin matrix protein 1 (DMP1-C) and proteoglycan versions of DSP (DSP-PG) and DMP1 (DMP1-PG) are tested for their roles in collagen assembly. These preliminary studies suggest that collagen fibrillogenesis can be influenced by the addition of some SIBLING proteins. The effects of SIBLINGs on the early stages of collagen fibrillogenesis were investigated using a solution of collagen, a fibrillogenesis buffer, and the SIBLING proteins individually. It was shown that DSP and DPP slowed down the fibril formation process significantly, while other SIBLINGs had limited impact. The effects of SIBLINGs in the presence or absence of calcium on the collagen denaturation process was also investigated. It was shown that calcium plays a role in speeding up the fibrillogenesis process, but it had a negative effect on collagen by reducing the extent of fibillogenesis and speeding up the denaturation process. Calcium did not have an effect on the proteoglycan version of DSP and DMP1, but it stabilized the performance of DPP.