人牙髓细胞内Smad2、3在转化生长因子β_1信号转导中的作用

The roles of Smad 2/3 in transforming growth factor-β_1 signaling in human dental pulp cells

目的 探讨人牙髓细胞内Smad 2、3在转化生长因子 β1 (transforminggrowthfactor β1 ,TGF β1 )信号转导过程中的作用。方法 原代培养人牙髓细胞 ,用激光共聚焦显微镜观察TGF β1 刺激初期牙髓细胞内Smad 2、3由胞质向胞核转位的现象 ,同时采用Westernblot方法检测刺激后期Smad 2、3蛋白表达的变化。结果 TGF β1 刺激 2h内 ,Smad 2、3在胞质中表达渐弱 ,在胞核内表达渐强 ,呈现由胞质向胞核逐步转位的趋势。Smad 2蛋白总量在TGF β1 刺激前后几乎无变化 ,而Smad 3在刺激后 2 4h表达量明显下降 ,48h后表达十分微弱。结论 Smad 2、3可能是人牙髓细胞内TGF β1 的信号转导分子。TGF β1 刺激初期Smad 2、3通过发生转位参与转导TGF β1 信号至核内 ,刺激后期Smad 3表达水平的下调可能与TGF β1

Objective To explore the roles of Smad 2/3 in transforming growth factor β 1(TGF β 1) signaling by human dental pulp cells Methods Laser scanning confocal microscope was used to observe translocation of Smad 2/3 from plasma into nucleus in cultured dental pulp cells at early stage of TGF β 1 treatment, and changes of Smad 2/3 protein expression at later stage were evaluated by Western blot analyses Results The expression of Smad 2/3 (fluorescence intensity)kept decreasing in cytoplasm but increasing in nucleus within 2 h after TGF β 1 treatment, forming a trend that Smad 2/3 translocated into nucleus from cytoplasma The total amount of Smad 2 protein remained unchanged before and after TGF β 1 treatment, but the expression level of Smad 3 decreased markedly after 24 h treatment and kept droping by 48 h Conclusions The results suggest that the Smad 2/3 may be the downstream signal transducers of TGF β 1 in human dental pulp cells and Smad 2/3 may mediate TGF β 1 signaling by translocation early in TGF β 1 treatment, while down regulation of Smad 3 expression by TGF β 1 at later stage is involved in negative modulation of TGF β 1 signaling