Identification of a glucocorticoid repressor domain in the rat beta 1-adrenergic receptor gene.
The expression of the gene encoding the rat beta 1-adrenergic receptor is suppressed by glucocorticoids (Kiely et al., 1994). Within the 3.2-kb 5'-flanking region of the promoter, two potential glucocorticoid response elements (GREs) at -950 and -2791 relative to the translational ATG were identified. Characterization of the glucocorticoid-responsive sequences in the 5'-flanking region of the beta 1-adrenergic receptor gene was explored in rat C6 glioma cells and human HepG2 hepatoma cells using transient expression of beta 1-adrenergic receptor-luciferase fusion genes. The ability of glucocorticoids to suppress luciferase expression was not altered when the most 5'-localized GRE was deleted. Deleting the potential GRE at -950, in contrast, abolished glucocorticoid-induced suppression of the beta 1-adrenergic receptor-luciferase gene transcription. A 25-bp element containing the GRE sequence between nucleotides -950 and -926 confers glucocorticoid-dependent inhibition of transcription to a neutral promoter. Gel mobility shift assays with the alpha-subunit of the human glucocorticoid receptor (hGR alpha) expressed in reticulocyte lysates demonstrated specific binding to the 25-bp sequence harboring the putative GRE. We report an inhibitory GRE in the promoter of the rat beta 1-adrenergic receptor gene that is conserved among the rat, human, and mouse genes.
Bahouth
S W
SW
Department of Pharmacology, College of Medicine, University of Tennessee Memphis 38163, USA.
Park
E A
EA
Beauchamp
M
M
Cui
X
X
Malbon
C C
CC
D000818:Animals; D006528:Carcinoma, Hepatocellular; D003907:Dexamethasone / Q000494:pharmacology; D005796:Genes / Q000187:drug effects; D005910:Glioma; D005938:Glucocorticoids / Q000235:genetics* / Q000494:pharmacology*; D006801:Humans; D011401:Promoter Regions, Genetic / Q000187:drug effects; D051381:Rats; D018342:Receptors, Adrenergic, beta-1 / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D012045:Regulatory Sequences, Nucleic Acid / Q000187:drug effects; D014407:Tumor Cells, Cultured
D005938:Glucocorticoids; D018342:Receptors, Adrenergic, beta-1; D003907:Dexamethasone