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© The Rockefeller University Press,
0021-9525/1999//185 $5.00
The Journal of Cell Biology, Volume 147, Number 1,
, 1999 185-194
Original Article |
Endothelial Claudin
: Claudin-5/Tmvcf Constitutes Tight Junction Strands in Endothelial Cells
b Department of Dermatology, Faculty of Medicine, Kyoto University, Kyoto 606-8501, Japan
c Laboratory of Cell Biology, KAN Research Institute Inc., Kyoto Research Park, Kyoto 600-8317, Japan
d Department of Molecular Cell Biology, Institute of DNA Medicine, The Jikei University School of Medicine, Tokyo 105-8461, Japan
Department of Cell Biology, Kyoto University Faculty of Medicine, Konoe-Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.81-75-753-466081-75-753-4372
htsukita{at}mfour.med.kyoto-u.ac.jp
Tight junctions (TJs) in endothelial cells are thought to determine vascular permeability. Recently, claudin-1 to -15 were identified as major components of TJ strands. Among these, claudin-5 (also called transmembrane protein deleted in velo-cardio-facial syndrome [TMVCF]) was expressed ubiquitously, even in organs lacking epithelial tissues, suggesting the possible involvement of this claudin species in endothelial TJs. We then obtained a claudin-6–specific polyclonal antibody and a polyclonal antibody that recognized both claudin-5/TMVCF and claudin-6. In the brain and lung, immunofluorescence microscopy with these polyclonal antibodies showed that claudin-5/TMVCF was exclusively concentrated at cell–cell borders of endothelial cells of all segments of blood vessels, but not at those of epithelial cells. Immunoreplica electron microscopy revealed that claudin-5/TMVCF was a component of TJ strands. In contrast, in the kidney, the claudin-5/TMVCF signal was restricted to endothelial cells of arteries, but was undetectable in those of veins and capillaries. In addition, in all other tissues we examined, claudin-5/TMVCF was specifically detected in endothelial cells of some segments of blood vessels, but not in epithelial cells. Furthermore, when claudin-5/TMVCF cDNA was introduced into mouse L fibroblasts, TJ strands were reconstituted that resembled those in endothelial cells in vivo, i.e., the extracellular face–associated TJs. These findings indicated that claudin-5/TMVCF is an endothelial cell–specific component of TJ strands.
Key Words: claudin occludin endothelium tight junction blood vessels
© 1999 The Rockefeller University Press
1.used in this paper: aa, amino acid(s); BBB, blood–brain barrier; E-face, extracellular face; GST, glutathione S-transferase; pAb, polyclonal antibody; PECAM, platelet endothelial cell adhesion molecule; P-face, protoplasmic face; TJ, tight junction; TMVCF, transmembrane protein deleted in velo-cardio-facial syndrome; VE-cadherin, vascular endothelial–cadherin
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