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目的探讨富含半胱氨酸的酸性分泌蛋白(SPARC)是否与盘状结构域受体2(DDR2)竞争性结合胶原蛋白,并观察SPARC对DDR2磷酸化水平的影响。方法采用转染小干扰RNA的方法下调人前列腺癌细胞PC-3中DDR2的表达,观察对该细胞中SPARC mRNA表达水平的影响。在HEK293T细胞中同时过表达SPARC和DDR2,在有无胶原蛋白刺激的情况下,通过免疫沉淀及Western blot法检测DDR2磷酸化水平的变化。结果下调DDR2会引起SPARC mRNA和蛋白表达水平显著下降;而SPARC能够抑制胶原蛋白刺激的DDR2磷酸化。结论 SPARC很可能通过竞争性结合胶原蛋白来抑制DDR2的活化。
Objective To investigate whether cysteine-rich acidic secreted protein (SPARC) competes with collagen 2 in DDR2 and observe the effects of SPARC on DDR2 phosphorylation. Methods The expression of DDR2 in human prostate cancer cell line PC-3 was down-regulated by siRNA. The expression of SPARC mRNA in this cell line was observed. SPARC and DDR2 were overexpressed in HEK293T cells, and the changes of DDR2 phosphorylation were detected by immunoprecipitation and Western blot in the presence or absence of collagen stimulation. Results The downregulation of DDR2 caused a significant decrease of SPARC mRNA and protein expression, whereas SPARC inhibited collagen-stimulated DDR2 phosphorylation. Conclusion SPARC is likely to inhibit DDR2 activation by competitively binding collagen.