QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

Vol. 15, Issue 10, 4347-4355, October 2004

This Article Full Text Full Text (PDF) All Versions of this Article: E04-03-0203v1 15/10/4347    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Thomas, B. E. Articles by Thekkumkara, T. J. Search for Related Content PubMed PubMed Citation Articles by Thomas, B. E. Articles by Thekkumkara, T. J.

Glucose Mediates Transcriptional Repression of the Human Angiotensin Type-1 Receptor Gene: Role for a Novel Cis-acting Element

Department of Pharmaceutical Sciences, Texas Tech University Health Sciences Center, Amarillo, TX 79106

Submitted March 11, 2004; Revised June 26, 2004; Accepted July 7, 2004
Monitoring Editor: Suzanne Pfeffer

Human angiotensin type 1 receptor (hAT1R) gene is regulated by hormones, second messengers, and both pathophysiological and developmental states. The focus of the present study was to determine the role of glucose in the trans-repression of hAT1R gene transcription and to identify the functional cis-acting response element(s). Serial deletions of the hAT1R promoter region indicated that an area between –1717 and –1543 base pairs upstream of the 5' end of the cDNA sequence has a glucose responsive regulatory element (GluRE) to down-regulate the gene expression. Further analysis revealed a putative 29-bp (5'-AACTGATTTTTGTATATTGATCTTGTATT-3') repressor element located between –1582 and -1610 bp was necessary for transcriptional repression. Removal of this region from promoter construct abolished repression of the hAT1R gene transcription in human proximal tubule epithelial cells (hPTECs). Using mobility shift assays, we demonstrated DNA binding activity to the labeled repressor element in hPTEC nuclear extracts. Additional studies demonstrated increased DNA binding activity to the labeled repressor element in nuclear extracts treated with high glucose (25 mM). Southwestern analysis identified two GluRE binding proteins of 34 and 36 kDa in glucose-treated extracts. Glucose-induced activity of the repressor trans-acting factor(s) reached a maximum at 4 h, which correlated with decreased transcriptional activity of the hAT1R gene, suggesting that glucose can down-regulate the transcription of the hAT1R gene through the repressor element. Furthermore, insertion of the glucose response element into heterologous SV40 promoter (SV40) chloramphenicol acetyl transferase (CAT) vector showed orientation/distance-independent repression of SV40 promoter-mediated CAT activity in hPTECs. Our results show that the glucose response factor(s) acts as trans-acting factor(s) binding to the cis-acting repressor element in the hAT1R promoter, which may participate in the control of basal transcription as well as glucose-mediated transcriptional inhibition of the hAT1R gene.

Abbreviations used: AngII, angiotensin II; CAT, chloramphenicol acetyl transferase; ChoRE, carbohydrate response element; COUP-TFII, chicken ovalbumin upstream promoter-transcription factor II; GIRE, glucose-induced response element; hAT1R, human angiotensin type 1 receptor; hPTEC, human proximal tubule epithelial cell; GluRE, glucose response element; NRE, negative regulatory element; USF, upstream stimulatory factor.

^* Corresponding author. E-mail address: thomas.thekkumkara{at}ttuhsc.edu.

This article has been cited by other articles:

				T. S. Elton and M. M. Martin Angiotensin II Type 1 Receptor Gene Regulation: Transcriptional and Posttranscriptional Mechanisms Hypertension, May 1, 2007; 49(5): 953 - 961. [Full Text] [PDF]

				T. Samikkannu, J. J. Thomas, G. J. Bhat, V. Wittman, and T. J. Thekkumkara Acute effect of high glucose on long-term cell growth: a role for transient glucose increase in proximal tubule cell injury Am J Physiol Renal Physiol, July 1, 2006; 291(1): F162 - F175. [Abstract] [Full Text] [PDF]