Glucocorticoids regulate the human occludin gene through a single imperfect palindromic glucocorticoid response element
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BioMed Central
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Meeting abstract
Glucocorticoids regulate the human occludin gene through a single imperfect palindromic glucocorticoid response element M Burek*1, N Harke2, J Leers3, S Kietz4, D Drenckhahn2 and C Förster1 Address: 1University of Wuerzburg, Department of Anaesthesiology, Zentrum of Operative Medicine, Germany, 2University of Wuerzburg, Institute of Anatomy and Cell Biology, Würzburg, Germany, 3University of Giessen, Institute of Genetics, Giessen, Germany and 4University of Goettingen, Institute of Pediatrics, Göttingen, Germany * Corresponding author
from 12th Joint Meeting of the Signal Transduction Society (STS). Signal Transduction: Receptors, Mediators and Genes Weimar, Germany. 29–31 October 2008 Published: 26 February 2009 Cell Communication and Signaling 2009, 7(Suppl 1):A96
doi:10.1186/1478-811X-7-S1-A96
12th Joint Meeting of the Signal Transduction Society (STS). Signal Transduction: Receptors, Mediators and Genes
Frank Entschladen, Karlheinz Friedrich, Ralf Hass and Ottmar Janssen Meeting abstracts – A single PDF containing all abstracts in this Supplement is available here.This abstract is available from: http://www.biosignaling.com/content/7/S1/A96 © 2009 Burek et al; licensee BioMed Central Ltd.
The 65 kDa protein occludin is an essential element of the blood-brain barrier. This integral membrane protein represents an important part of the tight junctions, which seal and protect the blood brain barrier against paracellular diffusion of solutes to the brain parenchyme and are therefore responsible for the high resistance and low permeability between cerebral capillary endothelial cells. However, the molecular basis for the regulation of occludin gene expression is only incompletely understood. In former projects we showed that treatment of a brain microvascular cell line, cEND, with glucocorticoids resulted in increased occludin expression in cell-cell-contacts Induction of occludin expression by glucocorticoids was shown to be dependent on the glucocorticoid receptor. This study aims to identify the underlying molecular mechanism of gene expression and to identify potential glucocorticoid receptor binding sites within the occludin promoter, the glucocorticoid response elements (GRE). We identified one candidate GRE within the distal part of the occludin promoter that differs from the consensus GRE by the presence of a 4-basepair instead of a 3-basepair spacer between two highly degenerate halfsites (5'ACATGTGTTTACAAAT-3'). Chromatin immunoprecipitation assay and site-directed mutagenesis confirmed binding of the glucocorticoid receptor to this site. We synthesized plasmid containing four copies of this GRE in the vector pGL-3 basic. After stimulation of the cells with hydrocortisone we could observe up to 8-fold increased activity in luciferase reporter assay. The need for glucocorticoid receptor dimerization to induce gene expression
was further confirmed by transfection studies using wild type and glucocorticoid receptor dimerization-deficient expressio
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