Transforming growth factor β induces bone marrow mesenchymal stem cell migration via noncanonical signals and N‐cadherin

Abstract

Transforming growth factor‐beta (TGF‐β) induces the migration and mobilization of bone marrow‐derived mesenchymal stem cells (BM‐MSCs) to maintain bone homeostasis during bone remodeling and facilitate the repair of peripheral tissues. Although many studies have reported the mechanisms through which TGF‐β mediates the migration of various types of cells, including cancer cells, the intrinsic cellular mechanisms underlying cellular migration, and mobilization of BM‐MSCs mediated by TGF‐β are unclear. In this study, we showed that TGF‐β activated noncanonical signaling molecules, such as Akt, extracellular signal‐regulated kinase 1/2 (ERK1/2), focal adhesion kinase (FAK), and p38, via TGF‐β type I receptor in human BM‐MSCs and murine BM‐MSC‐like ST2 cells. Inhibition of Rac1 by NSC23766 and Src by PP2 resulted in impaired TGF‐β‐mediated migration. These results suggested that the Smad‐independent, noncanonical signals activated by TGF‐β were necessary for migration. We also showed that N‐cadherin‐dependent intercellular interactions were required for TGF‐β‐mediated migration using functional inhibition of N‐cadherin with EDTA treatment and a neutralizing antibody (GC‐4 antibody) or siRNA‐mediated knockdown of N‐cadherin. However, N‐cadherin knockdown did not affect the global activation of noncanonical signals in response to TGF‐β. Therefore, these results suggested that the migration of BM‐MSCs in response to TGF‐β was mediated through N‐cadherin and noncanonical TGF‐β signals.