title: Exogenous expression of claudin-5 induces barrier properties in cultured rat brain capillary endothelial cells.
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 x 10(-3) and 11.6 x 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.
authors.affiliation: Department of Molecular Biopharmacy and Genetics, Graduate School of Pharmaceutical Sciences,Tohoku University, Aoba, Aramaki, Aoba-ku, Sendai, Japan.
authors.forename: Sumio
authors.initials: S
authors.lastname: Ohtsuki
authors.forename: Saori
authors.initials: S
authors.lastname: Sato
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Yamaguchi
authors.forename: Mayu
authors.initials: M
authors.lastname: Kamoi
authors.forename: Tomoko
authors.initials: T
authors.lastname: Asashima
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Terasaki
mesh_terms: D000818:Animals; D001812:Blood-Brain Barrier / Q000737:chemistry / Q000166:cytology / Q000378:metabolism*; D015153:Blotting, Western; D002199:Capillary Permeability; D002460:Cell Line; D062507:Claudin-5; D042783:Endothelial Cells / Q000737:chemistry / Q000378:metabolism*; D007150:Immunohistochemistry; D007444:Inulin / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D010750:Phosphoproteins / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019108:Tight Junctions / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D062826:Zonula Occludens-1 Protein
chemical_list: D062507:Claudin-5; C491510:Cldn5 protein, rat; D008565:Membrane Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; C569043:Tjp1 protein, mouse; C569044:Tjp1 protein, rat; D062826:Zonula Occludens-1 Protein; D007444:Inulin