Claudin-21 Has a Paracellular Channel Role at Tight Junctions

Abstract
Claudin protein family members, of which there are at least 27 in humans and mice, polymerize to form tight junctions (TJs) between epithelial cells, in a tissue- and developmental stage-specific manner. Claudins have a paracellular barrier function. In addition, certain claudins function as paracellular channels for small ions and/or solutes by forming selective pores at the TJs, although the specific claudins involved and their functional mechanisms are still in question. Here we show for the first time that claudin-21, which is more highly expressed in the embryonic than the postnatal stages, acts as a paracellular channel for small cations, such as Na+, similar to the typical channel-type claudins claudin-2 and -15. Claudin-21 also allows the paracellular passage of larger solutes. Our findings suggest that claudin-21-based TJs allow the passage of small and larger solutes by both paracellular channel-based and some additional mechanisms. © 2016, American Society for Microbiology. All Rights Reserved.

Citation
Tanaka H, Yamamoto Y, Kashihara H, Yamazaki Y, Tani K, et al. (2016) Claudin-21 Has a Paracellular Channel Role at Tight Junctions. Mol Cell Biol 36: 954–964. Available: http://dx.doi.org/10.1128/mcb.00758-15.

Acknowledgements
Ministry of Education, Culture, Sports, Science, and Technology (MEXT) provided funding to Sachiko Tsukita under grant number 24247037. Ministry of Education, Culture, Sports, Science, and Technology (MEXT) provided funding to Yoshinori Fujiyoshi under grant number 22227004. Ministry of Education, Culture, Sports, Science, and Technology (MEXT) provided funding to Kazutoshi Tani under grant number 26440024. Ministry of Education, Culture, Sports, Science, and Technology (MEXT) provided funding to Kosei Takeuchi. Core Research for Evolutional Science and Technology, Japan Science and Technology Agency (CREST, JST) provided funding to Sachiko Tsukita.

Publisher
American Society for Microbiology

Journal
Molecular and Cellular Biology

DOI
10.1128/mcb.00758-15

PubMed ID
26729464

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