Exogenous expression of claudin-5 induces barrier properties in cultured rat brain capillary endothelial cells

✍ Scribed by Sumio Ohtsuki; Saori Sato; Hirofumi Yamaguchi; Mayu Kamoi; Tomoko Asashima; Tetsuya Terasaki

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 235 KB
• Volume: 210
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/jcp.20823

✦ Synopsis

Abstract

Claudins are thought to be major components of tight junctions (TJs), and claudin‐5 and ‐12 are localized at TJs of the blood‐brain barrier (BBB). Claudin‐5‐deficient mice exhibit size‐selective (<800 Da) opening of the BBB. The purpose of this study was to clarify the expression levels of claudin‐5 and ‐12 in rat brain capillary endothelial cells, and to examine the ability of claudin‐5 to form TJs in cultured rat brain capillary endothelial cells (TR‐BBB). Expression of claudin‐5 mRNA in rat brain capillary fraction was 751‐fold greater than that of claudin‐12. The level of claudin‐5 mRNA in the rat brain capillary fraction (per total mRNA) was 35.6‐fold greater than that in whole brain, while the level of claudin‐12 mRNA was only 13.9% of that in whole brain, suggesting that expression of claudin‐12 mRNA is not restricted to brain capillaries. Transfection of TR‐BBB cells with the claudin‐5 gene afforded TR‐BBB/CLD5 cells, which showed no change in expression of claudin‐12 or ZO‐1, while the expressed claudin‐5 was detected at the cell–cell boundaries. The permeability surface product of [^14^C]inulin at a TR‐BBB/CLD5 cell monolayer was significantly smaller (P < 0.01) than that for the parental TR‐BBB cells, and the values of the permeability coefficient (Pe) were 1.14 × 10^−3^ and 11.6 × 10^−3^ cm/min, respectively. These results indicate that claudin‐5, but not claudin‐12, is predominantly expressed in brain capillaries, and plays a key role in the appearance of barrier properties of brain capillary endothelial cells. J. Cell. Physiol. 210: 81–86, 2007. © 2006 Wiley‐Liss, Inc.