Basal level transcriptional regulation of the human angiotensin II type 1 receptor gene

The peptide hormone angiotensin II regulates a variety of physiological res ponses which are mediated by its interaction with high affinity G protein-c oupled receptors localized on the surface of target cells. To gain insights into the transcriptional regulation of the human angiotensin II type 1 rec eptor (hAT(1)R) gene, we have isolated 1 kb of the 5'-flanking sequence of this gene. Expression constructs containing various 5'-deletions of the hAT (1)R promoter region, fused upstream to the luciferase reporter gene, were transiently transfected into H295-R, HEC-1B and A549 cells. It was demonstr ated that a 145 bp sequence within the promoter region was required for bas al level expression of the hAT(1)R gene in all of the three cell lines inve stigated. Computer analysis indicated the existence of numerous putative tr anscription factor binding sites in this region. Further detailed deletion data suggested essential transcription factor binding sites between -98 and -79 bp. Electrophoretic mobility shift assays revealed that four protein-D NA complexes were formed within the -98 to -79 bp region of the hAT1R gene when incubated with H295-R cell nuclear extract. Site-directed mutagenesis experiments showed that a putative Spl binding site was critical for the ba sal level expression of the hAT(1)R gene. (C) 2000 Elsevier Science B.V. Al l rights reserved.