Transcription of the Rat β1-Adrenergic Receptor Gene

Abstract

We have characterized the 5′ and 3′ ends of the rat β1-adrenergic receptor transcript using RNase protection assays and have used transient transfection analysis to identify regions of the β1-adrenergic gene 5′-flanking sequences which are important for expression. The transcript has multiple start sites, occurring primarily in two clusters at bases −250 and −280, relative to the first base of the initiation codon. Two potential polyadenylation signals at +2450 and +2732 are both functional, although the site at +2732 is preferred both in C6 glioma cells and in heart tissue. Characterization of the gene by transient transfection analysis has identified a region between bases −389 and −325 which is necessary for expression. The specific deletion of a potentially functional inverted CCAAT sequence within this region does not significantly alter activity. In addition to the region from −389 and −325, deletion of the bases between −1 and −159 and between −186 and −211 significantly alters expression. Both of these regions are downstream from the β1-adrenergic receptor gene start sites and may function either through regulation of transcription or through alteration of the transcript structure. We have characterized the 5′ and 3′ ends of the rat β1-adrenergic receptor transcript using RNase protection assays and have used transient transfection analysis to identify regions of the β1-adrenergic gene 5′-flanking sequences which are important for expression. The transcript has multiple start sites, occurring primarily in two clusters at bases −250 and −280, relative to the first base of the initiation codon. Two potential polyadenylation signals at +2450 and +2732 are both functional, although the site at +2732 is preferred both in C6 glioma cells and in heart tissue. Characterization of the gene by transient transfection analysis has identified a region between bases −389 and −325 which is necessary for expression. The specific deletion of a potentially functional inverted CCAAT sequence within this region does not significantly alter activity. In addition to the region from −389 and −325, deletion of the bases between −1 and −159 and between −186 and −211 significantly alters expression. Both of these regions are downstream from the β1-adrenergic receptor gene start sites and may function either through regulation of transcription or through alteration of the transcript structure.