SOX-18 controls endothelial-specific claudin-5 gene expression and barrier function

• Published in: American journal of physiology. Heart and circulatory physiology Vol. 294; no. 2; pp. H891 - H900
• Main Authors: Fontijn, Ruud D, Volger, Oscar L, Fledderus, Joost O, Reijerkerk, Arie, de Vries, Helga E, Horrevoets, Anton J. G
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.02.2008
• Subjects: Binding sites; Blotting, Western; Cells; Cells, Cultured; Claudin-5; Electrophoresis, Polyacrylamide Gel; Endothelial Cells - physiology; Endothelium, Vascular - metabolism; Fluorescent Antibody Technique; Gene expression; Gene Expression - physiology; Genes; Genes, Reporter - genetics; High Mobility Group Proteins - genetics; High Mobility Group Proteins - physiology; Humans; Lentivirus - genetics; Membrane Proteins - genetics; Mutation; Nucleic Acid Hybridization; Oligonucleotide Array Sequence Analysis; Promoter Regions, Genetic - genetics; Reverse Transcriptase Polymerase Chain Reaction; RNA - biosynthesis; RNA - genetics; SOXF Transcription Factors; Transcription Factors - genetics; Transcription Factors - physiology; Transcription, Genetic; Umbilical Veins - cytology; Umbilical Veins - physiology
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.01248.2007

1 Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, Amsterdam, the Netherlands; and 2 Department of Molecular Cell Biology and Immunology, VU University Medical Center, Amsterdam, The Netherlands Submitted 29 October 2007 ; accepted in final form 5 December 2007 Members of the claudin family constitute tight junction strands and are major determinants in specificity and selectivity of paracellular barriers. Transcriptional control of claudin gene expression is essential to establish individual claudin expression patterns and barrier properties. Using full genome expression profiling, we now identify sex-determining region Y-box (SOX)-18, a member of the SOX family of high-mobility group box transcription factors, as one of the most differentially induced genes during establishment of the endothelial barrier. We show that overexpression of SOX-18 and a dominant-negative mutant thereof, as well as SOX-18 silencing, greatly affect levels of claudin-5 (CLDN5). The relevance of an evolutionary conserved SOX-binding site in the CLDN5 promoter is shown using sequential promoter deletions, as well as point mutations. Furthermore, SOX-18 silencing abrogates endothelial barrier function, as measured by electric cell-substrate impedance sensing. Thus an obligatory role for SOX-18 in the regulation of CLDN5 gene expression in an endothelial-specific and cell density-dependent manner is established, as well as a crucial, nonredundant role for specifically SOX-18 in the formation of the endothelial barrier. endothelium; claudin; promoter; sox Address for reprint requests and other correspondence: A. J. G. Horrevoets, Dept. of Medical Biochemistry, Academic Medical Center K1-114, Meibergdreef 15, 1105 AZ Amsterdam, The Netherlands (e-mail: a.j.horrevoets{at}amc.uva.nl )