FIG. 4.
(A) hPGC-1 enhances responses to steroids in a receptor-selective manner. Expression plasmids for ER, AR, MR, or GR were cotransfected into COS7 cells with control (hatched bars), hPGC-1 (black bars), or SRC-1e (gray bars) expression vectors and the following luciferase reporters: pERE-TK-luc for ER, pMMTVDLO (MMTV) for AR and GR, and pTAT3Luc (TAT3) for MR and GR. Cells were treated with 50 nM estradiol (ER), aldosterone (MR), or corticosterone (GR) or 100 nM dihydroxytestosterone (AR) for 24 h and assayed for luciferase activity. Results are expressed as fold enhancement by the coactivator in the presence of hormone; i.e., activity in the presence of hormone and absence of coactivator was set equal to 1 for all receptors. (B) hPGC-1 is not a general activator of transcription. COS7 cells were transfected with expression and reporter plasmids for either the two NF-κB subunits p50 and p60 (left panel) or the chimeric activator Gal4-VP16 (right panel) and assayed for luciferase activity. LU, luciferase units. Error bars show standard deviations.