Fig. 4.

BAP31-deletion in hepatocytes promotes SREBP signaling activation and increases the response to fasting/refeeding treatment. A: Immunoblot analysis of SREBP1C precursor and nuclear form in WT and MT mice fed the SD or HFD for 96 days. *P < 0.05, MT compared with WT mice fed SD. ^$P < 0.05, MT compared with WT mice fed HFD. B, C: Immunoblot analysis of SREBP1C precursor and nuclear form in HepG2 cell lines with stable knockdown of the BAP31 gene or with overexpression of the BAP31 gene. D: Immunoblot analysis of INSIG1 in WT and MT mice fed the SD. Statistical differences were determined by a two-tailed Student’s t-test. *P < 0.05, MT compared with WT mice fed SD. E: Liver lysates (SD and HFD mouse livers) were subjected to immunoprecipitation assay with polyclonal anti-BAP31 antibody. Immunoprecipitated proteins were probed by immunoblot with anti-SREBP1, anti-INSIG1, anti-SCAP, and anti-BAP31 antibodies. F: Male WT and MT mice were fasted 24 h and then refed the SD for 1 h or 6 h, respectively. Hepatic TGs, FFA, and Chol were extracted and quantified spectrophotometrically (n = 6 per group). G: Total RNA was extracted from the livers of WT and MT mice fasted 24 h followed by refeeding the SD for 6 h. The relative mRNA levels were determined by real-time PCR and normalized with 18S rRNA levels (n = 6 per group). *P < 0.05, MT compared with WT mice refed for 6 h. H: Immunoblot analysis of BAP31 in mice fed the SD or HFD for 96 days. GAPDH and lamin B1 were used as a loading control. Statistical differences were determined by a two-tailed Student’s t-test. *P < 0.05, mice fed HFD compared with SD.