The activation of Wnt signaling facilitates autophagy by modulating GSK-3-AMPK axis in atherosclerosis

Background Endothelial dysfunction induced by oxidized low-density lipoprotein (ox-LDL) is implicated in the pathogenesis of atherosclerosis (AS). Activated autophagy was reported to improve endothelial functions and alleviate AS development. AMPK is a key protein in the regulation of autophagy, which can be modulated by Wnt signaling pathway. Objective Our study was designed to explore whether the canonical Wnt activator Wnt3a promotes autophagy in AS through in vitro and in vivo assays. Results Human umbilical vein endothelial cells (HUVECs) were first treated with ox-LDL at 50 mu g/mL for 24 h and then transfected with Wnt3a-overexpressed plasmid pcDNA3.1/Wnt3a. At 48 h after transfection, HUVECs were treated with 100 mu M 3-MA. To investigate the effects of GSK-3 beta inhibition on the activation of AMPK, HUVECs were treated with 10 mu M TWS119. Cell viability was detected via Trypan blue staining. Wnt3a expression, autophagy markers, GSK-3 beta inhibition and AMPK activation were examined by western blotting. To induce animal model of AS, male apolipoprotein E deficient (ApoE(-/-)) mice were fed with high-fat diet. pcDNA3.1/Wnt3a was injected into ApoE(-/-) mice after high-fat diet induction. Oil Red O staining was performed to examine lipid and plaque deposition in atherosclerotic lesions. In this study, ox-LDL treatment decreased HUVEC viability and downregulated Wnt3a expression. Wnt3a overexpression promoted autophagy, induced GSK-3 beta phosphorylation at Ser9, and AMPK phosphorylation at Thr172 in ox-LDL-stimulated HUVECs. Overexpressing Wnt3a ameliorated lipid accumulation in aortic plaque of ApoE(-/-) mice. Furthermore, Wnt3a overexpression also activated autophagy, and induced GSK-3 beta and AMPK phosphorylation in ApoE(-/-) mice. Conclusion Wnt3a activates AMPK through inhibiting GSK-3 beta, thereby facilitating autophagy in AS.