Wnt／β-连环蛋白信号通路参与调节糖皮质激素诱导的阿尔茨海默病样病变

Wnt/β-catenin pathway regulating glucocorticoids-mediated Alzheimer＇ s disease-like pathological changes

目的探讨Wnt／β-连环蛋白（catenin）信号通路在糖皮质激素（glucocoaicoids，GC）诱导的阿尔茨海默病样病变中的信号调节机制。方法地塞米松（dexamethasone，DEX）分别处理转染人tau441的人胚肾293细胞（HEK293／tau）和野生型的人胚肾293细胞（HEK293／wt），采用细胞计数试剂盒（CCK-8）法检测DEX对细胞活力的影响，Westernblot研究两组细胞tau蛋白磷酸化（p-T205，Tau-1）、β—catenin、P—β-catenin、B细胞淋巴瘤／白血病-2蛋白（Bcl-2）及其上游激酶糖原合成激酶-3B（GSK-3B）、ps9-GSK-3p水平的变化，并加用GSK-3β的抑制剂氯化锂（LiCl），观察其对相关蛋白相应的逆转作用。结果CCK-8细胞活力检测结果显示，1μmol／LDEX处理细胞48h，HEK293／wt组细胞活力（存活率）下降到95．5％±3．2％，HEK293／tau组下降到77．8％±4．4％，两者差异有统计学意义（t=6．60，P〈0．05）；Westernblot结果显示，1μmol／LDEX处理两组细胞48h，使得HEK293／tau细胞ps9-GSK3β、Tau—1、β-catenin、Bcl-2水平分别下降到对照组的47．8％±10．4％、53．9％±11．7％、50．9％±7．6％、48．4％±6．5％，差异均有统计学意义（t=7．01、3．86、7．09、7．30，均P〈0．05），而P—T205、P—β—catenin相对磷酸化水平分别增加到对照组的180．5％±22．2％、201．3％±27．6％，差异均有统计学意义（t=5．51、5．27，均P〈0．05）；LiCl可以相应逆转上述改变。结论在人tau存在的前提下，GC通过抑制Wnt／β-catenin信号转导通路，促进了HEK293／tau细胞的阿尔茨海默病样病变。

Objective To investigate the role of Wnt/β-catenin pathway in the glucocorticoids （GC）-mediated Alzheimer＇ s disease-like pathological changes in vitro. Methods Human embryonic kidney 293 （HEK293/wt） cells stably transfected with the longest human tau （tau441 ,HEK293/tau） and wild-type HEK293 cells were employed to study the role of GC. Cell viabilities of the two cell lines were examined by cell counting kit-8 （CCK-8）. Levels of phosphorylated tau （p-T205） and dephosphorylated tau （ Tau-1 ）, β-catenin, phosphorylated β-catenin （p-β-catenin）, glycogen synthase kinase-3β （ GSK-3β）, phosphorylated GSK-3β at Ser9 （ps9-GSK-3β） and Bcl-2 were determined by Western blotting. Results Treatment with 1 Ixmol/L GC for 48 h decreased the viability of HEK293/wt and HEK293/tau cells to 95. 5% ± 3.2% and 77. 8% ± 4.4% （t = 6. 60, P 〈 0. 05）. Moreover, GC treatment decreased the levels ofps9-GSK3β, Tau-1, β-catenin and Bcl-2 to 47.8%±10.4%, 53.9% ±11.7%, 50.9% ±7.6%, 48.4%± 6. 5% of control groups （ t = 7.01,3.86,7.09,7.30, all P 〈 0.05 ）, and increased the relative levels of pT205, p-β-eatenin to 180. 5% ± 22. 2% , 201.3% ± 27.6% of control groups （ t = 5.51,5.27, both P 〈 0. 05 ） only in HEK293/tau cells. Finally, LiC1 efficiently prevented the above effects of GC in HEK293/tau cells. Conclusion GC may trigger Alzheimer＇ s disease-like pathological changes by inhibiting the Wnt/β-catenin pathway and these pathological processes seem to specifically depend on the presence of human tau.