Involvement of Rac1 in the micro/nano-topography sensing and osteogenic differentiation in bone marrow mesenchymal stem cells

Abstract

The cell responses to different topographies have been observed for decades while the related mechanisms are still blurring. In the present study, we aim to test whether the Rac1, a member of Rho GTPases family that plays a crucial role in actin cytoskeleton dynamics, is involved in the micro/nano-topography (MNT) sensing and cell differentiation in rat bone marrow mesenchymal stem cells (rBMMSCs). Firstly, we found that the cell morphology was distinct on different topographies and the actin arrangement was significantly different, suggesting that the actin cytoskeleton was influenced by MNT. In the next, we found that the Rac1 expression was significantly improved on MNT surface and the actin cytoskeleton was severely impaired after Rac1 silencing. Then the osteogenic differentiation was performed to figure out whether the Rac1 was involved in cell differentiation that regulated by MNT surface. It was notable that the MNT could promote osteogenic differentiation, which was significantly inhibited after Rac1 silencing. Further analysis indicated that the ERK1/2 and p38, members of mitogen-activated protein kinase (MAPK) pathway, were regulated by Rac1. In conclusion, the Rac1 is involved in MNT sensing and may play a crucial role in cell differentiation regulation through the MAPK pathway.