Fig. 6
Ex-4 promotes Ins2-encoding insulin via the Wnt/β-catenin pathway in the high-glucose-damaged HT22 cells. A–C HT22 cells under the control (CON) or high glucose (50 mM, HG) environment for 48 h, then part of the cells in the HG group were treated with exendin-4 (10 nM, HG + Ex-4) for 48 h. A Immunoblot and its gray density demonstrated the level of np-β-catenin to total β-catenin; β-actin was the internal control. n = 4. B Nuclear and cytoplasmic fractions were separated to describe the level of β-catenin by immunoblotting and its gray density. Histone H3 and β-actin as internal control, respectively. n = 4. C Represented immunofluorescence for β-catenin (red) and DAPI (blue). Scale bar = 100 μm. D–H HT22 cells were cultured in high glucose (50 mM, HG) environment for 48 h and then divided into four groups. The HG group was treated with saline, and the HG + Ex-4 group was treated with 10 nM Ex-4, the HG + Dkk1 group was treated with 100 ng/μl Dkk1, the HG + DKK1 + Ex-4 group was pretreated with 100 ng/μl Dkk1 for 2 h before Ex-4 was added, then kept for 48 h. D Immunoblot demonstrated the Wnt/β-catenin signalling activation by the level of np-β-catenin and total β-catenin. E Tau phosphorylated levels at specific sites and total tau were examined by Immunoblot. F The insulin signalling activation described by the total AKT, P-AKTS473, total GSK-3β, and P-GSK-3βS9 was examined through Immunoblot. n = 4. G mRNA levels of Ins2 were measured by RT-qPCR assay. n = 4. (H) Insulin in the culture supernatants was measured by an ELISA kit. n = 4. For D–G β-actin as the internal standard. Results are representative of three independent experiments. Data are presented as the mean ± SD. *P < 0.05, **P < 0.01, ***P < 0.001; N.S. no significant difference