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The expression of Smad2 and Smad3 and the influence of exogenous transforming growth factorβ 1 (TGFβ 1) on them in rat bone marrow-derived mesenchymal stem cells (MSCs) cultured in vitro were investigated. The effects of different concentrations of TGFβ 1 on cell proliferation and ALP activity were detected by MTT and PNPP in MSCs respectively. The expression of Smad2 and Smad3 and the influence of exogenous TGFβ 1 on them were also examined by immunocytochemistry and Western blot assays. The exogenous TGFβ 1 induced a dose-dependent decrease in cell proliferation and a dose-dependent increase in ALP activity, which plateaued at 5 ng/ml. Smad2 and Smad3 proteins were detected only in the cytoplasm in the absence of TGFβ 1 and TGFβ 1 could stimulate the translocation of them from the cytoplasm to the nucleus. The total amount of Smad2 protein remained unchanged before and after TGFβ 1 treatment (P>0.05). The expression levels of Smad3 remained unchanged after 3 h and 6 h treatment (P>0.05), but decreased markedly after 24 h treatment (P<0.05). It was concluded that TGFβ 1 is a latent osteoinductive factor involved in osteoblastic differentiation. Both Samd2 and Smad3 mediate TGFβ 1 signaling as downstream mediators in MSCs. The biological output of TGFβ 1 triggering the osteoblastic differentiation could be entirely determined by Smad3 in MSCs.
The expression of Smad2 and Smad3 and the influence of exogenous transforming growth factor β 1 (TGFβ 1) on them in rat bone marrow-derived mesenchymal stem cells (MSCs) cultured in vitro were. The effects of different concentrations of TGFβ 1 on cell proliferation and the expression of Smad3 and the influence of exogenous TGFβ 1 on them were also examined by immunocytochemistry and Western blot assays. The exogenous TGFβ 1 induced a dose-dependent decrease in cell proliferation and a dose-dependent increase in ALP activity, which plateaued at 5 ng / ml. Smad2 and Smad3 proteins were detected in the cytoplasm in the absence of TGFβ1 and TGFβ1 could stimulate the translocation of them from the cytoplasm to the nucleus . The total amount of Smad2 protein remained unchanged before and after TGFβ 1 treatment (P> 0.05). The expression levels of Smad3 remained unchanged a It was concluded that TGFβ 1 is a latent osteoinductive factor involved in osteoblastic differentiation. Both Samd2 and Smad3 mediate TGFβ 1 signaling (P <0.05), but decreased markedly after 24 h treatment as the downstream mediators in MSCs. The biological output of TGFβ 1 triggering the osteoblastic differentiation could be determined by Smad3 in MSCs.