Active JNK2 downregulated β-catenin expression, inhibited its transcriptional activity and reduced GSK3β phosphorylation.

<p>(A) Active JNK2 suppressed β-catenin expression and GSK3β phosphorylation in HEK293T cells. HEK293T cells were transfected with pcDNA3-HA-β-catenin together with pcDNA3-Flag-MKK7-JNK1 or pcDNA3-Flag-MKK7-JNK2. Forty-eight hours after transfection, cells were harvested for immunoblotting analysis to detect the alterations of HA-β-catenin, p-JNK, p-c-Jun, phospho-Ser⁹ GSK3β, and GSK3β. β-actin served as loading control. (B) Active JNK2 reduced GSK3β phosphorylation and downregulated β-catenin expression in human lung cancer cell line A549. A549 cells were co-transfected with pcDNA3-HA-β-catenin and pcDNA3-Flag-MKK7-JNK2. Forty-eight hours after transfection, cells were harvested for immunoblotting analysis to detect the alterations of β-catenin, p-JNK, and phospho-Ser⁹ GSK3β. β-actin served as loading control. (C) Active JNK inhibited β-catenin-mediated transcriptional activity of TCF. HEK293T cells were co-transfected with pcDNA3-Flag-MKK7-JNK1 or pcDNA3-Flag-MKK7-JNK2, pcDNA3-HA-β-catenin, TOPFLASH (TOP) or FOPFLASH (FOP), and Renilla. 48 h after transfection, cells were harvested for luciferase activity assay. Each bar represents the mean ± standard deviation (SD) for triplicated samples.