Functional analysis of the 5' flanking sequence in the ovine beta 1-adrenergic receptor gene.

Functional data for the promoter of the beta 1-adrenergic receptor (beta 1AR) gene are lacking. We previously cloned the ovine beta 1AR gene and mapped the transcription start sites. We now report data on ovine beta 1AR gene expression obtained by transient transfection. Progressive deletion of upstream 5' flanking region moderately increased transcription activity in three cell lines compared to the full-length promoter. Deletion of sequences between -1530 and -953 produced the greatest increase in transcriptional activity. This region encompassed a putative GRE and an AP1 site. Deletion of the transcription start sites eliminated nearly all of the activity. Dexamethasone significantly increased activity of each of the promoter constructs tested in C6 glioma cells and an embryonic myocardial cell line, W1 cells. T3 alone had no effect and cotreatment with T3 did not augment the effects of dexamethasone. We conclude, basal transcription activity is repressed by a mechanism which operates through element(s) in the proximal promoter. Glucocorticoids increase transcription through mechanism(s) within the same region. We speculate that this region in the ovine beta 1AR promoter may be responsible for its unique transcription regulation.