ERK信号分子介导周期机械拉伸诱导的骨髓间充质干细胞增殖

Proliferation of bone marrow mesenchymal stem cells induced by cyclic mechanical stretch mediated with ERK signal molecules

目的研究周期机械拉伸加载对大鼠骨髓间充质干细胞增殖的影响及其相关力信号转导分子。方法应用周期机械拉伸加载装置研究不同参数的周期机械拉伸加载对大鼠骨髓间充质干细胞生长的影响。RT-PCR法检测c-fos mRNA表达的变化,Western blotting分析细胞外信号调节激酶(ERK1/2)磷酸化水平及c-fos蛋白表达的变化。结果适宜的机械拉伸加载可以明显促进大鼠骨髓间充质干细胞增殖,在频率1 Hz、形变量10%、拉伸15 min且静止6 h的条件下可以使细胞数量增加到对照组的1.4倍,c-fos mRNA和蛋白的表达显著增加。Western blotting检测证实,周期性机械拉伸加载明显促进ERK1/2磷酸化,却不影响ERK1/2总蛋白(t-ERK1/2)的表达水平。抑制剂PD98059显著抑制了机械拉伸对细胞增殖的促进作用,同时抑制拉伸诱导的ERK1/2磷酸化及c-fos基因和蛋白的表达水平。结论 ERK1/2信号分子的活化在周期性机械拉伸加载调控大鼠骨髓间充质干细胞增殖的过程中起着重要作用,且该通路可能通过转录因子的调节促进rBMSCs的增殖。

Objective To investigate effects of the cyclic stretch on rat bone marrow mesenchymal stem cells（rBMSCs） proliferation and the related signal molecules.Methods The cyclic mechanical stretching apparatus was used to study the effects of the cyclic stretch on the growth of rBMSCs with different parameters.The expression of c-fos was measured by RT-PCR at mRNA level and the levels of phosphorylated extracellular signal-regulated kinase 1/2（p-ERK1/2）,total ERK1/2（t-ERK1/2） and c-fos proteins were detected by Western blotting.Results The proliferation of rBMSCs could be stimulated by the cyclic stretch,and the number of cells was increased to 1.4 times compared with that of the control group at 1 Hz,10% strain for 15 min and then being static for 6 h.Moreover,the expressions of c-fos mRNA and protein levels were increased significantly after the stimulation of the stretch.On the other hand,it was found that the cyclic stretch could remarkably enhance the phosphorylation of ERK1/2,but did not influence the level of t-ERK1/2.After treated with PD98059,the proliferation of rBMSCs stimulated by the cyclic stretch was inhibited prominently in a dose-dependent manner and the expressions of p-ERK1/2,as well as c-fos at gene and protein levels were sharply down-regulated.Conclusions ERK1/2 signal molecules play an important role in regulating the cyclic stretch on the proliferation of rBMSCs and transcription factors may take part in the regulations during this progress.