Zhang Yanquan, Wang Fang, Han Liang, Wu Yinyuan, Li Shan, Yang Xi, Wang Yinyin, Ren Fangli, Zhai Yonggong, Wang Dianjun, Jia Baoqing, Xia Yongjing, Chang Zhijie
State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Medicine, National Engineering Laboratory for Anti-tumor Therapeutics, Tsinghua University, Beijing, R.P. China.
Cell Physiol Biochem. 2011;27(5):503-12. doi: 10.1159/000329952. Epub 2011 Jun 15.
Wnt signaling is critical for many biological processes and is tightly regulated. In this study, we found that GABARAPL1 (GABA(A) receptor-associated protein like 1, GABARAPL1) interacts with Dvl2 by both yeast two-hybrid screening and immunoprecipitation experiments. Furthermore, we observed that p62 is required for the interaction of Dvl2 and GABARAPL1. Luciferase assays indicated that GABARAPL1 represses Wnt/β-catenin signaling stimulated by Wnt1, Dvl2 and β-catenin. We further demonstrated that GABARAPL1 mediates degradation of Dvl2 and the effect is blocked by addition of 3-MA, a specific inhibitor of autophagy. Finally, we provided evidence that over-expression of GABARAPL1 inhibits proliferation and tumor growth of MCF7 cells in vitro and in nude mice. Taken together, our results suggested that GABARAPL1 as a tumor repressor inhibits Wnt signaling via mediating Dvl2 degradation through the autophagy pathway.
Wnt信号通路对许多生物学过程至关重要且受到严格调控。在本研究中，我们通过酵母双杂交筛选和免疫沉淀实验发现GABARAPL1（γ-氨基丁酸A受体相关蛋白样1，GABARAPL1）与Dvl2相互作用。此外，我们观察到p62是Dvl2与GABARAPL1相互作用所必需的。荧光素酶检测表明，GABARAPL1抑制由Wnt1、Dvl2和β-连环蛋白刺激的Wnt/β-连环蛋白信号通路。我们进一步证明，GABARAPL1介导Dvl2的降解，且该效应可被自噬特异性抑制剂3-MA阻断。最后，我们提供证据表明，GABARAPL1的过表达在体外和裸鼠体内均抑制MCF7细胞的增殖和肿瘤生长。综上所述，我们的结果表明，作为肿瘤抑制因子的GABARAPL1通过自噬途径介导Dvl2降解来抑制Wnt信号通路。
