Activation of Wnt/beta-catenin pathway causes insulin resistance and increases lipogenesis in HepG2 cells via regulation of endoplasmic reticulum stress.

BACKGROUND: Wnt/beta-catenin signaling is involved in glucose and lipid metabolism, but the mechanism is not clear yet. AIM: The objective is to study mechanisms of Wnt/beta-catenin signaling on regulating hepatocytes metabolism. METHODS: Real-time qPCR, Western blot, and Oil-red O staining methods were used. RESULTS: The Wnt/beta-catenin signaling was activated in hepatocytes by CP21R7, and the level of phosphorylated IRS-1 (Ser307) and TRB3 were significantly increased, while the levels of phosphorylated IRS-1 (Tyr612) and phosphorylated Akt were decreased. Moreover, the expression of FGF21, FAS, SCD1, PPARgamma and ADRP was significantly increased. The expression of ATF4, ATF5, eIF2alpha, GRP78, CHOP and phosphorylated level of PERK were also increased. The expression of FGF21 and TRB3 was significantly down-regulated, and the lipid droplets were notably reduced after the ER stress was inhibited by TUDCA. The expression of FGF21 was significantly decreased when the IRE1 pathway of the UPR was inhibited by STF-083010. CONCLUSIONS: Activation of Wnt/beta-catenin signaling pathway could cause insulin resistance and lipogenesis in hepatocytes via regulation of the IRE1 pathway of the ER stress and UPR, providing new targets for the treatment of metabolic disorders.