Figure 5
Glucagon inhibits hepatic lipid synthesis via the mediation of CREBH and Insig-2 signaling.
(A,B) HepG2 cells (1 × 106) were cultured without FBS for 12 hours and then untreated or treated with 2 ng/ml glucagon for 24 hours. Cells were then harvested for total RNA and whole cell lysate preparation. (A) Protein mass of CREBH-F, CREBH-N, Insig-1 and Insig-2 were determined by immunoblot analysis (lanes were run on the same gel but noncontiguous, full images are shown in Supplementary Fig. 6). (B) Relative mRNA levels of Insig-2a by qRT-PCR in the glucagon treated HepG2 cells. (C) Four groups of WT or CREBH-KO (KO) mice were untreated or treated with glucagon (30 μg/kg) for 4 hours as detailed in the Methods. Total RNA was extracted from liver tissues and used to determine the mRNA expression of Insig-1 and Insig-2a by qRT-PCR. For animal studies, results are shown as mean ± SEM. n = 5–6/group. For in vitro studies, results are shown as means ± SD for two experiments that were performed in triplicate. *P < 0.05 versus controls.
