The extracellular matrix protein Edil3 stimulates osteoblast differentiation through the integrin α5β1/ERK/Runx2 pathway

Abstract

Epidermal growth factor-like repeats and discoidin I-like domain 3 (Edil3) is an extracellular matrix protein containing an Arg-Gly-Asp (RGD) motif that binds integrin. Recently, Edil3 has been implicated in various biological processes, including angiogenesis and cellular differentiation. It can inhibit inflammatory bone destruction. The objective of this study was to explore the role of Edil3 in osteoblast differentiation and its underlying molecular mechanisms. In wild-type mice, high expression levels of Edil3 mRNA were observed in isolated calvaria and tibia/femur bones. Immunohistochemical analysis showed that Edil3 protein was localized along periosteum and calcified regions surrounding bone tissues. When murine calvaria-derived MC3T3-E1 cells were cultured in osteogenic medium containing 50 μg/ml ascorbic acid and 5 mM β-glycerophosphate, Edil3 mRNA and protein expression levels were increased. Treatment with Edil3 protein in growth media increased expression levels of alkaline phosphatase and osteocalcin gene and phosphorylation level of extracellular signal-regulated kinase (ERK). Edil3 treatment with osteogenic medium induced mineralization. Treatment with a neutralizing antibody against α5β1 and MEK inhibitor U0126 inhibited Edil3-enhanced osteogenic marker gene expression and mineral deposition. Edil3 increased protein expression levels of transcription factor runt-related transcription factor2 (Runx2). Edil3-induced Runx2 protein expression was suppressed by pretreatment with U0126. Taken together, these results suggest that Edil3 may stimulate osteoblast differentiation and matrix mineralization by increasing expression of Runx2 through α5β1 integrin /ERK pathway.

1,25(OH)2D3regulates the proangiogenic activity of pericyte through VDR‐mediated modulation of VEGF production and signaling of VEGF and PDGF receptors

“…In PC, ERK regulates survival pathways through the activation of PDGF‐Rβ . Our data indicated sustained activation of ERK in PC incubated with 1,25(OH) 2 D 3 , which is consistent with the proposed role of ERK in VSMC calcification through modulation of Runx2 activity . Although, in retinal PC, no significant effect on ERK activation was observed by VEGF (100 pg/mL), the combination of VEGF and PDGF, similar to 1,25(OH) 2 D 3 , activated ERK (Figure B,E).…”

“…However, expression levels of integrins α 4 and α 5 β 1 increased in PC incubated with 1,25(OH) 2 D 3 . These results are consistent with binding of the α 5 β 1 and α 4 β 1 to FN and enhanced calcification by promoting osteoblastic differentiation of vascular smooth muscle cells (VSMC) through the ERK signaling pathway and enhanced Runx2 activity …”

“…The family of MAPK and AKT signaling pathways are involved in the regulation of diverse range of cellular processes including 1,25(OH) 2 D 3 mediated VSMC osteoblastic differentiation and calcification . Here, we examined the effect of 1,25(OH) 2 D 3 , VEGF, and VEGF and PDGF on MAPK protein expression and activity including p38 and extracellular‐signal‐regulated kinases (ERK), and AKT in PC (Figure ).…”

“…Although, in retinal PC, no significant effect on ERK activation was observed by VEGF (100 pg/mL), the combination of VEGF and PDGF, similar to 1,25(OH) 2 D 3 , activated ERK (Figure B,E). Thus, the inhibition of PC proliferation and migration by attenuation of signaling through VEGF‐R2 and PDGF‐Rβ by 1,25(OH) 2 D 3 or combination of VEGF and PDGF are concomitant with the activation of ERK, and increased expression of α 5 β 1 and enhanced adhesion to FN …”

Revealing hidden information in osteoblast’s mechanotransduction through analysis of time patterns of critical events

“…Integrins play a pivotal role in migration as well as in osteogenic differentiation and osteoblast activation [3,4,12,13]. The extracellular domain of integrins provides anchorage and interaction interface with the ECM, while ensembles of integrins, on the intracellular domain, are molecular sensors accumulating the effects of the external focal adhesion forces.…”