Premium
Deletion of claudin‐7 affects the expression of WNK4 kinase in vivo and in vitro
Author(s) -
Tatum Rodney,
Ding Lei,
Jeansonne Beverly,
Chen YanHua
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.1039.28
Subject(s) - claudin , in vivo , biology , endocrinology , medicine , microbiology and biotechnology , tight junction , genetics
Mutations in WNK4 kinase have been linked to hypertension in pseudohypoaldosteronism type II (PHAII). Paracellular ion transport has been reported to be involved in this disease process. We reported previously that claudin‐7 is a substrate of WNK4 and that ser206 in the C‐terminus of claudin‐7 is a putative phosphorylation site for WNK4. In this study, we investigate whether claudin‐7 deletion affects WNK4 expression. By Western blotting analysis using our claudin‐7 knockout mouse (Cldn7−/−) model, we found that WNK4 expression was reduced in Cldn7−/− kidneys than in Cldn7+/+ kidneys. To avoid compensation and hormone effects that could occur in vivo, we isolated primary epithelial cells of collecting ducts (CD) from kidneys using Dolichos biflorus lectin‐coated Dynabeads. Immunofluorescent light microscopy showed that claudin‐7 signals were strongly localized at the cell‐cell junctions of Cldn7+/+ CD cells while they were completely absent in Cldn7−/− CD cells. WNK4 expression was decreased in Cldn7−/− CD cells compared to that of Cldn7+/+ CD cells while AQP2 expression was not changed. This suggests that the increased AQP2 expression observed in Cldn7−/− mice was likely due to the compensatory effects in vivo since Cldn7−/− mice suffered from the chronic dehydration. We conclude that WNK4 expression is reduced both in vivo and in vitro when claudin‐7 is deleted. This work is supported by NIH grant HL085752.