Signal pathway involved in regulation of Cbfa1 expression in osteoblasts by icariin

Abstract

Objective To investigate the effects of icarrin on the activity and protein expression of core binding factor otl(Cbfa1) in rat osteoblasts cultured in vitro,and to explore whether mitogen-activated protein kinase (MAPK) pathway is involved in this process.Methods Calvarial osteoblasts were obtained from newborn (<24 h) SD rats by trypsin-coUagenase digestion method.The second generation osteoblasts were cultured in the medium containing icariin (10 ng/ml) or estradiol (10-8 mol/L) with or without extracellular-signal regulated kinase (ERK) inhibitor (UO126) or p38MAPK inhibitor (SB203580).Nuclear protein was extracted from osteoblasts.And then the activity of Cbfa1 was detected by ELISA.The amounts of Cbfa1 protein were detected by Western blot.Results Calvarial osteoblasts were obtained successfully and were used in this study after indentified by alkaline phosphatase and mineralized nodus staining.Cbfa1 expression and the activity in osteoblasts were up-regulated by both icariin and estradiol (P<0.05).The effects were partly inhibited by addition of U0126or SB203580 (P<0.05).Conclusions Either icarrin or estradiol can stimulate the proliferation and maturation of cultured osteoblasts in vitro via up-regulating the activity and expression of Cbfal.The MAPK signal pathway inhibitor seems to partly decrease Cbfa1 activity.It suggests that MAPK pathway may be involved in the transduction of icariin's impact on proliferation and mineralization of osteoblasts. Key words: Icariin; Flavones; Osteoblasts; Core binding factor-α1 ; Mitogen-activated protein kinase