Transcriptional regulation of the rat bradykinin B2 receptor gene: Identification of a silencer element

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Item Type:	Article
Title:	Transcriptional regulation of the rat bradykinin B2 receptor gene: Identification of a silencer element
Creators Name:	Baptista, H.A., Avellar, M.C.W., Araujo, R.C., Pesquero, J.L., Schanstra, J.P., Bascands, J.L., Esteve, J.P., Paiva, A.C.M., Bader, M. and Pesquero, J.B.
Abstract:	Kinins are involved in a variety of physiological and pathophysiological processes related to cardiovascular homeostasis, inflammation, blood flow, and nociception. Under physiological conditions, the bradykinin B2 (BKB2) receptor is constitutively expressed and mediates most of kinins' actions. However, the mechanisms regulating BKB2 receptor gene expression are still poorly understood. In this study, 4.6 kilobases of the 5′-flanking region from the rat BKB2 receptor gene were sequenced, and computer analysis revealed several sites for transcriptional factors. Nine promoter mutants were cloned in luciferase reporter gene vectors and transfected in NG108-15 cells and rat aorta vascular smooth muscle cells (VSMCs), showing several positive and negative regulatory elements. A classical silencer with 56 base pairs (bp) caused a decrease in reporter gene activity in NG108-15 cells and VSMCs and was able to inhibit the thymidine kinase promoter. Using electrophoretic mobility shift assay and surface plasmon resonance assay, protein-DNA interactions in the silencer region were determined and specific sets of protein-silencer complexes were detected in both cell types. More intense complexes were observed in the central 21 bp of the silencer and mutation in a putative SRE-1 site strongly impaired the protein-DNA binding. Down-regulation of the BKB2 receptor population in NG108-15 cells promoted by N6, 2′-O-dibutyryladenosine 3′:5′-cyclic monophosphate was paralleled by an increase in the amount of nuclear proteins bound to the silencer sequence showing an inverse relationship between protein-silencer complexes and the transcription of the BKB2 receptor gene. In summary, these data highlight the cell-specific regulation of the BKB2 receptor and the importance of a silencer element present in the regulatory region of the gene.
Keywords:	5 Flanking Region, Aorta, Base Sequence, Bradykinin B2 Receptor, Bradykinin Receptors, Cultured Tumor Cells, DNA, Gene Expression Regulation, Gene Silencing, Genetic Transcription, Molecular Sequence Data, Mutation, Promoter Regions, Transcriptional Silencer Elements, Transfection, Vascular Smooth Muscle, Animals, Mice, Rats
Source:	Molecular Pharmacology
ISSN:	0026-895X
Publisher:	American Chemical Society
Volume:	62
Number:	6
Page Range:	1344-1355
Date:	1 December 2002
Official Publication:	https://doi.org/10.1124/mol.62.6.1344
PubMed:	View item in PubMed

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