FIG 6.

SHBs elevates cAMP levels by regulating AC. (A) cAMP levels in the liver of LSL-SHBs and LSL-SHBs/Alb-Cre mice fasted for 16 h (n = 6 to 7 mice/group). (B to E) Effect of AC inhibitor SQ22536 or PDE inhibitor IBMX on cAMP levels (B), glucose production (C), gluconeogenic gene expression (D), CREB phosphorylation, and PKA activity (E) in Ad-SHBs-infected mouse primary hepatocytes and in Huh7-SHBs cells. Cells were treated with SQ22536 (500 μM) or IBMX (500 μM) for 1 h and then with glucagon (100 nM) stimulation or FSK (10 μM) for 15 min (B), 6 h (C), 2 h (D) and 30 min (E). (F) Huh7 cells were transfected with pcDNA 3.1-SHBs-Flag for 48 h, and then co-IP assays were performed to determine the interaction between SHBs and PKA subunits. The immunoprecipitated complexes with anti-Flag antibody were subjected to immunoblotting with PKA Cα, PKA RIα/β, PKA RIIα, or PKA RIIβ antibody. The glycosylated (gp) and nonglycosylated (p) forms of SHBs were indicated. Arrowhead points to phospho-CREB. Data are presented as means ± SEM. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ns, no significant difference.