Expression patterns of claudin family of tight-junction proteins in the mouse prostate.

Claudins are the transmembrane proteins forming the backbone of tight junctions, and consist of over 20 members of a gene family. Claudins are expressed in a tissue- and cell-type specific fashion, and changes in their abundance and/or distribution are proposed to play important roles in the pathophysiology of numerous disorders. In the prostate, claudin-1, -3, -4 and -7 transcripts are known to be expressed, but it is unknown regarding mRNA expression of other claudins or concerning expression and localization of claudin proteins in this organ. We herein show, by RT-PCR and Western blotting analyses, that not only these four claudins but also claudin-5, -8 and -10 are expressed in the normal mouse prostate. Claudin-3, -4, -5, -8 and -10 were primarily localized at the apicalmost sites of lateral membranes of luminal epithelial cells in the prostate gland, whereas claudin-1 and -7 were distributed along the basolateral membranes of the epithelium. These findings provide basic information for elucidating the significance of claudins in prostate diseases, including prostate cancers.