The Genomic Organization and Functional Analysis of the Promoter for the Human Angiotensin II Type 1 Receptor

We have cloned and characterized several human angiotensin II type 1 receptor (hAT1R) cDNAs by utilizing the 5'-RACE procedure. Sequence analysis demonstrated that human AT1 receptors are encoded by at least four distinct mRNA transcripts sharing an identical open reading frame, but differing in their organization of 5'-untranslated sequences. Therefore, even though multiple alternatively spliced forms of hAT1R mRNA are transcribed, they are all translated into identical receptors since the entire open reading frame of this receptor is harbored on a single exon. None of these exons coding for 5'-untranslated sequence is expressed in a tissue specific manner. By comparing the 5'-RACE cDNA clones with our hAT1R genomic clones, the organization of the hAT1R gene was determined. The human AT1 gene is comprised of at least four exons and spans at least 60 kb. Several putative promoter regions were characterized by utilizing primer extension and luciferase reporter gene constructs transfected into human adrenal cells. These results indicate that we have cloned a functional promoter for the hAT1R gene. Furthermore, this promoter harbors an adrenal specific response element.