Fig. 7.

cAMP/PKA signaling regulates steroidogenesis in Y1 cells via EGFR signaling. A and B, Y1 mouse adrenal cells were pretreated with 0.01% DMSO, 20 μm AG1478, 20 μm U0126, or 20 μm H89 for 30 min before stimulation with 50 nm ACTH plus inhibitors or DMSO for 2 h. A and B, Progesterone levels in the medium were measured by RIA (A) and Erk activation examined by Western blot (B). C, Y1 cells were treated with medium alone (Mock), 50 nm ACTH, or 10 μm cpTOME (gift from Alan Smrcka, University of Rochester) (24) for 30 min. Erk activation was then examined by Western blot. D, Cells were pretreated with 0.01% DMSO, 20 μm U0126, 20 μm AG1478, or 20 μm H89 for 30 min before stimulation with 10 μm forskolin plus inhibitors or DMSO for 2 h. Progesterone content in medium was measured by RIA. All experiments were performed at least three times with similar results. For A and C, each point represents the mean ± sem (n = 3). *, P < 0.05 by Student's t test relative to ACTH alone. P- and T-Erk, Phosphorylated and total Erk.