Role of ERK/NFκB in vanadium (IV) oxide mediated osteoblast differentiation in C3H10t1/2 cells

Abstract

Vanadium (V) compounds are reported to have insulin mimicking action, which render them to show excellent osteogenic activity. In the current study we investigated the effect of various vanadium compounds on osteoblast differentiation of mouse mesenchymal stem cells, C3H10t1/2 cells, and analyzed the underlying mechanism of vanadium for this action. Our data showed that treatment of C3H10t1/2 cells with V (IV) oxide complex (at 7-25 μM concentrations) induced osteoblast differentiation maximally as compared to V2O5. On the other hand, ammonium vanadate was found to dampen the osteoblast differentiation process. Based on this data, V (IV) oxide was investigated further to analyze its probable mode of action as an osteoblastic agent. The key factors implicated in osteoblast differentiation i.e., NFκB, ERK ½, AP1 and CRE were examined in response to V (IV) oxide exposure. Exposure to V (IV) oxide caused 2- and 5-folds induction of luciferase activities in cells transfected with SRE-luc and NFκB-luc reporter vectors respectively (p < 0.05). Further, exposure to V (IV) oxide enhanced the phosphorylation of ERK ½, IκB and NFκBp65 proteins. In addition, RT-PCR analysis, alizarin red staining and immunoblot analysis showed that inhibition of osteoblast differentiation in presence of PD98059 and parthenolide (inhibitors of ERK and NFκB pathways respectively) was rescued in presence of V (IV) oxide. These results suggest that V (IV) oxide up regulates osteoblast differentiation through ERK and NFκB pathways and hence could be utilized as an agent for bone formation after further analysis and validation.