Fig. 4.

Metformin and TUDCA inhibit GCDCA-induced UPR and cell death in primary hepatocytes. (A) C57BL/6 primary hepatocytes were pretreated with metformin (0.5 or 1 mM) for 1 h and then incubated with GCDCA (300 or 500 μM) for 6 h. Protein levels were measured by immunoblotting with antibodies against ATF4, CHOP, spliced XBP-1, Rip1, cleaved PARP-1, phospho-JNK, and α-tubulin. Asterisks indicate non-specific bands. (B, E) C57BL/6 primary hepatocytes were pretreated with metformin (0.5 mM) or TUDCA (200 μM) for 1 h and then incubated with GCDCA (300 μM) for 6 h. The CHOP mRNA levels were measured by performing qRT-PCR. Relative expression levels were normalized to GAPDH. Results are expressed as mean ± SD values and are representative of three independent experiments. **P < 0.01 vs. vehicle, ^##P < 0.01 vs. GCDCA. (C, F) The secreted amounts of CXCL10 in conditioned medium were determined by ELISA assay. Results are expressed as mean ± SE values and are representative of three independent experiments. *P < 0.05 vs. vehicle, ^#P < 0.05 vs. GCDCA. (D) C57BL/6 primary hepatocytes were pretreated with TUDCA (200 or 500 μM) for 1 h and then incubated with GCDCA (300 or 500 μM) for 6 h. Protein levels were measured by immunoblotting with antibodies against ATF4, CHOP, spliced XBP-1, Rip1, cleaved PARP-1, phospho-JNK, and α-tubulin. Asterisks indicate non-specific bands.