Functional role of a novel cis-acting element (GAGA box) in human type-1 angiotensin II receptor gene transcription

in Journal of Molecular Endocrinology

GH/growth factors have been shown to increase angiotensin type 1 receptor expression. In the present study we determined the cis-acting regulatory region controlling GH-induced transcription of the human type-1 angiotensin receptor (hAT(1)). In human proximal tubule cells transfected with a chloramphenicol acetyl transferase (CAT) reporter plasmid under the control of the hAT(1) promoter, GH induced CAT activity. Serial deletions of the hAT(1) promoter region indicated that an area between -314 bp and -70 bp upstream of the 5'-end of the cDNA sequence was essential for this activation to occur. Although sequence analysis identified putative multiple nuclear protein binding sites in this region, we determined that a 12 bp sequence (5'-GAGAGGGAGGAG-3', GAGA box) located between -161 bp and -149 bp was important for GH-mediated activation. Using mobility shift assays we demonstrated increased DNA binding activity to the labeled GAGA box in nuclear extracts treated with GH, suggesting this sequence is a GH response element. Southwestern analysis identified an 18 kDa GAGA box-binding protein (GAGA-BP). GH-induced activity of the GAGA-BP occurred within 2.5 min and reached a maximum at 5 min. Activation did not require de novo protein synthesis. Removal of the GAGA box abolished GH-induced transcription as well as basal transcription of the hAT(1) gene. Additional studies demonstrated that epidermal growth factor, platelet-derived growth factor and insulin activate the GAGA-BP, suggesting these growth factors can also regulate the transcription of the hAT(1) gene through the GAGA box. Our data show that the GAGA-BP acts as a trans-acting factor binding to the cis-acting regulatory element in the hAT(1) promoter, which is necessary for the basal and growth factor(s)-mediated transcriptional activation of the hAT(1) gene.

If the inline PDF is not rendering correctly, you can download the PDF file here.


      Society for Endocrinology

Related Articles

Article Information


All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 454 277 18
PDF Downloads 93 79 6



Google Scholar