FGF-2 signaling induces downregulation of TAZ protein in osteoblastic MC3T3-E1 cells.

Transcriptional coactivator with PDZ-binding motif (TAZ) protein is a coactivator of Runx2 and corepressor of PPARgamma. It also induces differentiation of mesenchymal cells into osteoblasts. In this study, we found that FGF-2, which inhibits bone mineralization and stimulates cell proliferation, reduced the TAZ protein expression level in osteoblast-like cells, MC3T3-E1. This reduction was recovered by removing FGF-2 from the culture medium, which also restored the osteoblastic features of MC3T3-E1 cells. Furthermore, FGF-2-induced reduction of TAZ is blocked by a SAPK/JNK-specific inhibitor. These findings suggest that the expression of TAZ protein is involved in osteoblast proliferation and differentiation. This may help elucidate the discrepancies in the effect of FGF-2 and contribute to the understanding of FGF/FGFR-associated craniosynostosis syndrome etiology and treatment.