雷奈酸锶通过TGF-β_1/Smad通路促进骨髓间充质干细胞向成骨细胞分化

Strontium ranelate promotes osteogenic differentiation of rat bone mesenchymal stem cells through TGF-β_1/Smad signaling pathway

目的:研究转化生长因子β1(TGF-β1)/Smad通路在雷奈酸锶(strontium ranelate,Sr)促进大鼠骨髓间充质干细胞(BMSCs)向成骨细胞分化中的作用。方法:在大鼠BMSCs向成骨细胞的诱导分化过程中,用Sr处理细胞,用Western blotting法检测磷酸化Smad2(phosphorylated Smad2,p-Smad2)和Runx2的表达。用TGF-β1特异性阻断剂SB431542或Smad2小干扰RNA(Smad2-siRNA)预处理BMSCs后加入Sr,再观察p-Smad2和Runx2表达的改变。应用试剂盒检测碱性磷酸酶(alkaline phosphatase,ALP)活性及钙结节水平。结果:在大鼠BMSCs向成骨细胞的诱导分化过程中,Sr可增加p-Smad2和Runx2的表达,Sr浓度为1 mmol/L、作用1 h时,p-Smad2表达最多;Sr浓度为1 mmol/L、作用5 d时,Runx2表达最多;用SB431542或Smad2-siRNA预处理BMSCs后再加入Sr,不仅可以抑制p-Smad2和Runx2的表达,且ALP活性与钙结节数量也受到明显的抑制。结论:Sr可通过TGF-β1/Smad通路促进大鼠BMSCs向成骨细胞分化。

AIM： To study the roles of transforming growth factor β1 （TGF-β1）/Smad signaling pathway in strontium ranelate （Sr）-induced osteogenic differentiation of rat bone marrow mesenchymal stem cells （BMSCs）. METH- ODS： In the process of osteogenic differentiation of rat BMSCs, the expression of phosphorylated Smad2 （p-Smad2） and Runx2 was detected by Western blotting after the cells were treated with Sr. BMSCs were pretreated with SB431542, a se- lective inhibitor of TGF-β, or Smad2 small interfering RNA （Smad2-siRNA）, followed by Sr treatment, and then the ex- pression of p-Smad2 and Runx2 was observed. At the same time, the activity of alkaline phosphatase （ALP） and the level of calcium nodules were detected to determine the osteogenic differentiation of BMSCs. RESULTS： The expression levels of p-Smad2 and Runx2 were enhanced under the action of Sr in the process of osteogenic differentiation of rat BMSCs. The expression of p-Smad2 reached to maximum when BMSCs were treated with Sr at concentration of 1 mmol/L for 1 h. The expression of Runx2 reached to maximum when BMSCs were treated with Sr at concentration of 1 mmol/L for 5 d. The pre- treatment with SB431542 or Smad2-siRNA inhibited not only the expression of p-Smad2 and Runx2, but also the activity of ALP and the level of calcium nodules. CONCLUSION： Sr promotes the osteogenic differentiation of rat BMSCs through the TGF-β1/Smad signaling pathway.