ERβ通过抑制SOST表达补偿ERα部分功能促进对成骨细胞增殖分化

The regulation of ERβ to the proliferation and differentiation of MC3T3-E1 by inhibition of SOST signaling

目的观察ERα和ERβ调控前体成骨细胞增殖和分化中的相互作用及当ERα表达降低时,ERβ的激活能否通过抑制SOST信号传递补偿ERα部分功能调控成细胞增殖。方法利用RNA干扰技术,以小鼠前体成骨细胞株MC3T3-E1为对象,采用随机分层设计的对照研究,将细胞随机分层设计分组为4个组,根据研究需要再将相关组再进一步分为7个亚组,进行相关干预处理。检测各组细胞周期、MTT法绘制细胞生长曲线、检测SOST、OPG和Run X2等细胞因子的表达。应用SPSS16.0进行统计分析各组间差异,显著性差异定为P<0.05。结果 ERα表达正常,单独沉默ERβ的表达(D组),细胞增殖稍增加,但与空白对照组(F组)比较,没有显著性差异,P>0.05。同时沉默ERα和ERβ(E组),细胞增殖明显减少,SOST基因表达反而增强,但是OPG和Run X2的表达相对于空白对照组显著减弱,与空白对照组和B组比较,有显著性差异,P<0.05。沉默ERα表达而保持ERβ正常表达(B组),成骨细胞增殖能力明显减弱,SOST基因表达减弱,OPG和Run X2的表达相对于空白对照组明显减弱,和空白对照组比较差异有显著性P<0.05。相反,沉默ERα表达,但应用ERβ激动剂使ERβ过表达(A组),与B组和E组比较,细胞增殖能力反而明显增强,但是SOST基因表达显著降低,OPG和Run X2的表达反而升高,有显著性差异,P<0.05。在E组细胞的培养液中加入SOST抗体(G组),和E组比较,OPG和Run X2蛋白表达明显增强,两组间差异有显著性,P<0.05;这一结果与A组中应用ERβ激动剂有相似作用。结论 ERβ对ERα调控成骨细胞增殖过程中起着平衡作用,当ERα正常表达或活性增高时,ERβ抵抗ERα在骨形成中的刺激作用;当ERα活性减弱或丧失后,ERβ的激活补偿ERα刺激成骨细胞的增殖和分化,并且这一过程是通过ERβ抑制SOST表达而增强成骨细胞增殖相关细胞因子OPG和Run X2等而独立发挥作用。

Objective To investigate if ERβ activation may partly compensate the absence of ERα activity for regulation to the proliferation of osteoblastic cells by inhibiting SOST signaling.Me thods In the model of hierarchical design,the precursor osteoblast cell line MC3T3-E1 cells firstly were randomly divided into four groups,then the ERαRNAi group,ERβRNAi group and ERα-ERβRNAi group is further divided into 2 subgroups,respectively,total seven subgroups.Each group cells were cultured under the same conditions and the different treatments were used separately.the cell cycle,cell growth curve,and the cytokines SOST,OPG and Run X2 were detected,respectively.SPSS16.0 statistical software was used for statistical analysis of differences between groups,significant differences was set at P〈0.05.Re sults In the case of silence of ERβ expression but not ERα（ group D）,the cell proliferation was slightly increased,but compared with the control group（ group F）,no significant difference was found,P〈0.05.Meanwhile the ERα and ERβ expression were simultaneously silenced（ group E）,the cell proliferation was significantly reduced,and SOST gene expression has actually strengthened,but the expression of OPG and Run X2 r were significantly decreased compared with the control group and group B,there was significant difference,P〈0.05.If the expression of ERα was silenced while maintained ERβ normal expression（ group B）,the osteoblast proliferation was significantly decreased,and the gene expression of SOST,OPG and Run X2 were significantly decreased compared with the control group,the difference was significant P〈0.05.Instead,while the expression of ERα was silent,ERβ agonist was used for ERβ overexpression（ A group）,compared with group B and group E,the cells proliferation were significantly increased,and the expression of OPG and Run X2 were increased,but the SOST gene expression was significantly decreased,there is a significant difference,P〈0.05.However,if SOST antibody were added into the culture medium of cells in the group E（ G group）,the protein expression of OPG and Run X2 were significantly increased compared with group E,there is a significant difference,P〈0.05.and This result is similar to the group A,between the two groups was not significant,P〈0.05.Conclusion ERβ may play a subtle balance function for ERα inducing osteoblasts proliferation and differentiation.The resistance effect of ERβ to ERα was found when ERα activity was normal or increased.But the compensation for the absence of ERα activity by ERβ was found by the mild effect of down-regulation of SOST expression,compared with deletion of both ERs in the osteoblastic cells,and in turn regulates the proliferative context of osteoblasts and related cytokines genes expression,such as OPG and Run X2,in response to estradiol.