Sonic Hedgehog Signaling Molecules Expression in TGF-β1-Induced Chondrogenic Differentiation of Rat Mesenchymal Stem Cells In Vitro

Sonic Hedgehog (SHH) is involved in the induction of early artilaginous differentiation of mesenchymal cells in the limb and in the spine. Transforming growth factor beta 1 (TGF-β1) promotes chondrogenic differentiation of bone marrow mesenchymal stem cells (MSCs), while the signaling pathway by which TGF-β1 affects chondrogenic differentiation remains obscure. This study aimed to investigate expression of SHH- signaling molecules SHH and GLI1 during TGF-β1-induced chondrogenic differentiation of rat MSCs in vitro. TGF-β1 promoted chondrogenic differentiation of MSCs at 10 ng/ml from 7 to 21 days, demonstrated by enhancing cartilage markers collagen type II expression during chondrogenic differentiation. Expressions of Shh and Gli1, were tested by RT-PCR and western blot analysis during chondrogenic differentiation. Expressions of Shh and Gli1 were decreased compared to the control on both mRNA and protein level during TGF-β1-induced chondrogenic differentiation of MSCs from 7 to 21 days. Altogether, these data demonstrate that inactivation of SHH-GLI1 pathway during TGF-β1-induced chondrogenic differentiation of MSCs in vitro. These findings provide new data for the mechanistic link between TGF-β1-induced chondrogenic differentiation and Hedgehog signaling pathway.