FOXP1 promotes osteoblast differentiation via regulation of TGF-?/ALK-5 pathway

Osteoblast differentiation plays a crucial role in the development of skeleton. The purpose of this study was to investigate the role of FOXP1 in osteoblast differentiation. Expressions of FOXP1, ALP, OSX, and OCN were upregulated in MC3T3-E1 cells during osteoblast differentiation. Downregulation of FOXP1 inhibited the expressions of ALP, OSX, and OCN. ALP activity was reduced by inhibition of FOXP1. Osteoblast mineralization was suppressed by knockdown of FOXP1. The knockdown of FOXP1 also downregulated the expressions of TGF-??, ALK-5, and Smad4 and inhibited the phosphorylation of Smad2/3. Repression of ALK-5 attenuated the effects of FOXP1 on MC3T3-E1 cells during osteoblast differentiation. In summary, data of this study demonstrated that upregulation of FOXP1 enhanced osteoblast differentiation through enhancing activation of TGF-??/ALK-5 pathway.