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Selective decrease in paracellular conductance of tight junctions: role of the first extracellular domain of claudin-5.

Huajie Wen·Debbie D Watry·M Cecilia G Marcondes·Howard S Fox
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Abstract

Claudin-5 is a protein component of many endothelial tight junctions, including those at the blood-brain barrier, a barrier that limits molecular exchanges between the central nervous system and the circulatory system. To test the contribution of claudin-5 to this barrier function of tight junctions, we expressed murine claudin-5 in Madin-Darby canine kidney II cells. The result was a fivefold increase in transepithelial resistance in claudin-5 transductants and a reduction in conductance of monovalent cations. However, the paracellular flux of neither neutral nor charged monosaccharides was significantly changed in claudin-5 transductants compared to controls. Therefore, expression of claudin-5 selectively decreased the permeability to ions. Additionally, site-directed mutations of particular amino acid residues in the first extracellular domain of claudin-5 altered the properties of the tight junctions formed in response to claudin-5 expression. In particular, the conserved cysteines were crucial: mutation of either cysteine abolishted the ability of claudin-5 to increase transepithelial resistance, and mutation of Cys(64) strikingly increased the paracellular flux of monosaccharides. These new insights into the functions of claudin-5 at the molecular level in tight junctions may account for some aspects of the blood-brain barrier's selective permeability.

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Amino Acid SequenceAnimalsCysteineMannitolMembrane ProteinsMiceMicroscopy, ConfocalMolecular Sequence DataMutationTight JunctionsJournal ArticleResearch Support, U.S. Gov't, P.H.S.

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Huajie Wen, Debbie D Watry, M Cecilia G Marcondes, Howard S Fox. 2004. Selective decrease in paracellular conductance of tight junctions: role of the first extracellular domain of claudin-5.. https://doi.org/10.1128/mcb.24.19.8408-8417.2004

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