中文摘要：

目的探讨Smad7在Sox9增强BMP2成软骨效应中的作用和机制。方法将小鼠骨髓间充质干细胞（C3H10T1/2）作为种子细胞,重组腺病毒Ad-BMP2和/或Ad-Sox9感染细胞,Ad-GFP感染细胞为对照。采用Real-time PCR、免疫细胞化学和Western blot分别检测感染后各组Smad7 mRNA表达水平和蛋白表达水平。采用Real-time PCR检测与Smad7相关因子MMP13与OPN mRNA的表达。结果 BMP2＋Sox9组感染细胞7、11 d时,Smad7 mRNA和蛋白表达水平均明显低于BMP2组（P〈0.05）;免疫细胞化学染色结果显示,BMP2＋Sox9组Smad7染色明显弱于BMP2组;同时BMP2＋Sox9组中与软骨最终成熟因子OPN与MMP13的表达均低于BMP2组（P〈0.05）。结论在BMP2诱导间充质干细胞成软骨分化中,高表达的Smad7可被Sox9抑制,并抑制Smad7相关因子MMP13与OPN表达,从而解除了Smad7对BMP2成软骨的抑制作用,阻止了软骨细胞最终成熟骨化,有利于保持软骨发育与正常状态。

英文摘要：

Objective To determine the role of Smad7 （mothers against decapentaplegic homolog 7） in bone morphogengetic protein 2 （BMP2）-induced chondrogenic differentiation which was potentiated by Sox9 （sex determing region Y-related high mobility group-box gene 9） and investigate the underlying mechanism. Methods Mouse bone marrow mesenchymal stem cell line C3H10T1/2 was transfected with recombinant adenovirnses Ad-GFP （as control ）, Ad-BMP2, Ad-Sox9 and Ad-BMP2 ＋ Ad-Sox9 respectively. The expression of Smad7 at mRNA and protein levels was measured by real-time PCR, immunocytochemical staining and Western blot analysis. Real-time PCR and Western blot analysis was also used to detect the expression of Smad7 related factors MMP13 and osteopontin （OPN）. Results When the C3H10T1/2 ceils were transfected with recombinant adenoviruses Ad-BMP2 ＋ Ad-Sox9 for 7 and 11 d, the mRNA and protein expression of Smad7 was significantly lower than in the cells transfected by Ad-BMP2 （P 〈 0. 05 ）, and similar results were also found by immunocytochemical staining. What＇ s more, the over-expression of Sox9 also effectively reduced the expression of MMP13 and OPN at mRNA and protein levels than the Ad-BMP2- transfected cells （P 〈 0. 05 ）. Conclusion In the BMP2-induced chondrogenic differentiation of mouse mesenchymal stem cells, the over-expression of Smad7 is suppressed by Sox9, so is the expression of Smad7 related factors, MMP13 and OPN. Thus, the inhibitory effect of Smad7 on chondrogenic differentiation is relieved, which prevent the maturation of ehondrocyts and then keep the normal status of chondrocyts in development.