Fig. 6.

Effect of c-fos or c-jun overexpression on hSERTp1 and hSERTp2 activities. A: expression of c-jun or c-fos. Cells were cotransfected with hSERT promoter constructs and mammalian expression vectors for c-fos or hemagglutinin (HA)-tagged c-jun along with the β-galactosidase vector. Cells were harvested after 24 h, and protein lysates were run on SDS-PAGE, followed by immunoblotting with anti-c-fos or anti-HA antibodies to examine the protein expression of c-fos and c-jun, respectively. β-Actin was used as an internal control. O/E, overexpressing. Data were obtained from 3 separate experiments. B: effect of c-fos overexpression on hSERTp1 and hSERTp2 activities. Caco-2 cells were transiently transfected with c-fos mammalian expression vector for 24 h along with promoter construct hSERTp1 or hSERTp2. Control cells were transfected with empty vector for c-fos (PCDN3.1) and hSERTp1 or hSERTp2. Promoter activity was measured by luciferase assay normalized to β-galactosidase to adjust for transfection efficiency. c-fos overexpression failed to alter the activity of hSERTp1 or hSERTp2 compared with respective controls. Data are % of respective controls represented as means ± SE of 5 individual experiments performed in triplicate. C: c-jun overexpression transactivates hSERTp2 activity. Caco-2 cells were transiently transfected with c-jun mammalian expression vector for 24 h along with promoter construct hSERTp1 or hSERTp2. Control cells were cotransfected with empty vector and hSERTp1 or hSERTp2. c-jun overexpression transactivated hSERTp2, with no effect on hSERTp1 compared with their respective controls. Data are represented as % of control represented as means ± SE of 3 individual experiments performed in triplicate. *P < 0.001 compared with control.