Bone Abstracts

Epidermal growth factor-like repeats and discoidin I-like domains 3 (Edil3) is an extracellular matrix protein that contains Arg-Gly-Asp (RGD) motif to bind to integrins. Recently it has been reported that Edil3 is involved in various biological processes, including angiogenesis and cellular differentiation. This study was to explore the role of Edil3 in osteoblast differentiation and an underlining molecular mechanism. When MC3T3E1 cells were cultured with osteogenic medium, Edil3 mRNA and protein expressions were increased in a time-dependent fashion. Treatment of Edil3 protein led to the increases in alkaline phosphatase (ALP) and osteocalcin (OC) gene expressions and phosphorylation of ERK. A neutral antibody for α5β1 and MEK inhibitor U0126 inhibited the Edil3 induction of ALP and OC expression. Overexpression of Edil3 by lentiviral system resulted in matrix calcification, and U0126 inhibited the calcification. These results suggest that Edil3 may positively regulate osteoblast differentiation and matrix calcification via the integrin α5β1-ERK pathway.