C-JUN ACTIVATION OF THE DYNCRE3 SITE IN THE PRODYNORPHIN PROMOTER

The DYNCRE3 site in the prodynorphin promoter is similar to both the A P-I and cAMP-responsive element (CRE) consensus sequences. Because c-J un is known to bind to both AP-1 and CRE sequences, we evaluated the p otential role of this transcription factor at the DYNCRE3 site using t ransient transfection and gel mobility shift analyses. In PC12 cells, co-transfections of a chloramphenicol acetyl transferase (CAT) reporte r gene containing the DYNCRE3 site and a c-Jun expression vector resul ted in transcriptional activity 9-fold greater than control. Co-transf ections with a mutant c-Jun protein lacking the transactivation domain resulted in a concentration-dependent decrease in transcriptional act ivity. Gel mobility shift analysis demonstrated the formation of a mul ti-component protein-DNA complex between an oligonucleotide centered o n the DYNCRE3 site and nuclear extract from untreated and forskolin-st imulated PC12 cells. The upper band of this complex could be completel y supershifted with the addition of a c-Jun specific antibody. These c onvergent data suggest that c-Jun is involved in transcriptional activ ation through the DYNCRE3 site.