RNA interference-mediated knockdown of Smad1 inhibits receptor activator of nuclear factor κB ligand expression induced by BMP-2 in primary osteoblasts.

Objective: BMP-2 induces osteoblast differentiation and activates osteoclast formation. Here, we investigated the role of Smad1, a molecule that signals downstream of BMP-2, in mediating the effects of BMP-2 on osteoclast differentiation induced by 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) in osteoblasts.

Design: The effects of 1,25(OH)2D3 and BMP-2 in osteoclasts were examined using polymerase chain reaction and Western blotting to measure changes in target gene and protein expression.