Predicted expansion of the claudin multigene family

TLDR

Claudins are essential membrane proteins of tight junctions that form the paracellular permselective barrier and are encoded by a multi‑gene family of 24 members in mouse and human. Using a comprehensive search combined with phylogenetic analyses, we identified three novel claudins (claudin‑25, ‑26, and ‑27). Quantitative RT‑PCR showed tissue‑ and/or developmental stage‑dependent expression of the novel claudins, and immunofluorescence revealed that claudin‑25 and ‑26 localize to tight junctions in MDCK and Eph cells, expanding the claudin family to at least 27 members.

Abstract

Claudins (Cldn) are essential membrane proteins of tight junctions (TJs), which form the paracellular permselective barrier. They are produced by a multi-gene family of 24 reported members in mouse and human. Based on a comprehensive search combined with phylogenetic analyses, we identified three novel claudins (claudin-25, -26, and -27). Quantitative RT-PCR revealed that the three novel claudins were expressed in a tissue- and/or developmental stage-dependent manner. Claudins-25 and -26, but not claudin-27, were immunofluorescently localized to TJs when exogenously expressed in cultured MDCK and Eph epithelial cell lines. These findings expand the claudin family to include at least 27 members.