Osteogenic Proteome Analysis of Osteocalcin-Driven DMP1 Overexpression Mouse Calvaria
M. Bernard1, J.D. Padovano1 , A. Ramachandran1, A. George1
1 Department of Oral Biology, College of Dentistry, UIC, Chicago, IL, USA
Bone is a hierarchical biocomposite tissue composed of a type I collagen framework impregnated with non-collagenous proteins and carbonated
hydroxyapatite. Dentin Matrix Protein 1 (DMP1) is involved in osteoblast differentiation and critical for proper mineralization of the bone extracellular
matrix (ECM). Abnormalities in the expression of bone-matrix proteins results in pathological bone quality, such as in the case of osteogenesis
imperfecta, rickets and osteomalacia. Mammalian bone development occurs primarily by endochondral ossification in which bone replaces a cartilage
scaffold, while the flat bones of the skull are formed by intramembranous ossification. Osteoblast expression of osteogenic genes is a carefully
orchestrated process resulting in the formation of healthy bone. Osteocalcin (OCN) is the most abundantly expressed non-collagenous gene by
differening and mature osteoblasts and therefore its promoter is ideal for driving bone-specific expression of DMP1 during bone development. In
the present study, we generated a mouse model that overexpresses full-length rat DMP1 using the OCN promoter in an effort to achieve bone-specific
DMP1 overexpression. The goal of the present work was to analyze changes in the protein expression profile of key osteogenic proteins during early
post-natal development in male mice. Calvaria tissue was used to investigate changes osteogenic expression during intramembranous ossification.
This study was designed to explore the changes in osteogenic proteome with respect to the overexpression of a major bone forming protein,
DMP-1, using an osteocalcin promoter.
If we modulate DMP-1 at the genetic level, the expression of osteogenic proteins will be altered.
1)Runx2 increased temporally through 60 days and decreased at 90 days of development with statistical significance.
This indicates that DMP1 favors Runx2 expression thereby promoting osteoblast differentiation
2) Osteocalcin varied significantly at both 30 and 60 time points
3) FGF23 was undetectable at 15 days and did not significantly differ at remaining time point
4) DMP1 expression did not fluctuate amongst time points
NIH-NIDCR: F30DE023458, R01DE11657, T32DE018381, R01DE021040, ACC Protocol: 13-221