钙结合蛋白S100A6对Wnt／β-catenin信号途径的影响

Effects of Ca^2＋ -binding protein S100A6 on Wnt/β-catenin signaling pathway

目的研究钙结合蛋白S100A6对Wnt／β-catenin信号途径的影响及其机制。方法异丙基β-D-硫代半乳糖苷（IPTG）诱导表达、谷胱甘肽-琼脂糖球珠分离纯化融合蛋白GST-hS100A6；Westernblot和荧光素酶活性分析法检测S100A6对细胞内B—catenin水平和B—catenin／T细胞因子4（TCF4）活性的影响；GST-pulldown和Westernblot技术研究S100A6与该信号途径主要成员β-catenin、糖原合酶激酶-3β（GSK-3β）、Dvl和Axin之间的相互作用。结果S100A6可致MG63和HCT1 16细胞β—catenin水平升高，并可使HEK293细胞β—catenin／TCF4活性增强；S100A6与β—catenin、GSK-36和Dvl之间存在着直接的相互作用，而与Axin之间无相互作用。结论S100A6能够增强Wnt／β-catenin信号途径的活性，其机制可能涉及S100A6与该途径重要成员β—catenin、GSK-3β和Dvl之间存在着直接的相互作用有关。

Objective To analyze the effects of S100A6 on Wnt/β-catenin signaling pathway and its molecular mechanism. Methods The expression of GST-hS100A6 was induced with IPTG in Escherichia coli BL21, and the fusion protein was purified with glutathione-sepharose 4B beads. β-catenin level of human colon cancer cell line MG63 and human osteosarcoma cell line HCT1 16 ceils infected with AdS100A6 was measured by Western blot. Luciferase activity assay was applied to analyze the effect of S100A6 on the β-catenin/TCF4 activity. The interactions between S100A6 and β-catenin/GSK-3β/Dvl/Axin were detected by GST-pulldown/Western blot. Results The β-catenin level in AdS100A6-infected MG63 and HCT1 16 cells was significantly increased in comparison with that in the AdGFP control group （ P 〈 0.01 ）. The luciferase activity in human embryonic renal cell line 293 cells transfected with pTOP-Luc and followed by GST-hS100A6 treatment was increased by 20. 2-fold in comparison with that in the GST control group （P〈0.01）.The interaction between GST-hS100A6 and Axin was not found. Conclusion S100A6 upregulates the Wnt/β-catenin signaling pathway, and this may be attributed to the interaction between S100A6 and β-catenin/GSK-3 β/Dvl.