Figure 1. E1A12 represses the AR-mediated transactivation.

(A) E1A12 inhibits, but Ad5 E1A (E1A5) activates, AR NTD-mediated transactivation. The luciferase reporter containing five tandem Gal4-binding sites was cotransfected with the indicated constructs or the combinations thereof into Saos-2 cells. Luciferase activity was measured 24 h after transfection. Shown are the average values of relative reporter activity from three independent transfections along with the standard error of the mean (SEM). Lower panel: the expression of transfected constructs was detected with Western blotting. (B) The large isoforms of E1A from Ad3 (E1A3), Ad9 (E1A9), Ad40 (E1A40) and Ad4 (E1A4) also suppress the AR NTD. Luciferase reporter assays were done as in (A). Western blotting data of the transfected cells are shown in the lower panel. The Ad5 and Ad12 E1As were detected with an antiserum raised against Ad12 E1A, whereas the E1As from other Ad species were detected with an anti-GFP antibody. (C) The domain structure of E1A12. The conserved regions (CR1-CR4) along with sequences that bind to cellular proteins are depicted. The numbers refer to the positions of amino acid residues. The mutant constructs of E1A12 with specific point mutations or deletions that were used for reporter assays are also shown. (D and E) Effects of E1A12 mutations on AR NTD-mediated transcription. The reporter assays were done as in (A). Western blotting data of the transfected constructs are also shown.