Claudin-16 and claudin-19 interact and form a cation-selective tight junction complex
Jianghui Hou, … , Siegfried Waldegger, Daniel A. Goodenough
Jianghui Hou, … , Siegfried Waldegger, Daniel A. Goodenough
Published January 10, 2008
Citation Information: J Clin Invest. 2008;118(2):619-628. https://doi.org/10.1172/JCI33970.
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Research Article Nephrology

Claudin-16 and claudin-19 interact and form a cation-selective tight junction complex

Abstract

Tight junctions (TJs) play a key role in mediating paracellular ion reabsorption in the kidney. Familial hypomagnesemia with hypercalciuria and nephrocalcinosis (FHHNC) is an inherited disorder caused by mutations in the genes encoding the TJ proteins claudin-16 (CLDN16) and CLDN19; however, the mechanisms underlying the roles of these claudins in mediating paracellular ion reabsorption in the kidney are not understood. Here we showed that in pig kidney epithelial cells, CLDN19 functioned as a Cl– blocker, whereas CLDN16 functioned as a Na+ channel. Mutant forms of CLDN19 that are associated with FHHNC were unable to block Cl– permeation. Coexpression of CLDN16 and CLDN19 generated cation selectivity of the TJ in a synergistic manner, and CLDN16 and CLDN19 were observed to interact using several criteria. In addition, disruption of this interaction by introduction of FHHNC-causing mutant forms of either CLDN16 or CLDN19 abolished their synergistic effect. Our data show that CLDN16 interacts with CLDN19 and that their association confers a TJ with cation selectivity, suggesting a mechanism for the role of mutant forms of CLDN16 and CLDN19 in the development of FHHNC.

Authors

Jianghui Hou, Aparna Renigunta, Martin Konrad, Antonio S. Gomes, Eveline E. Schneeberger, David L. Paul, Siegfried Waldegger, Daniel A. Goodenough

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Figure 3

Cotrafficking and coimmunoprecipitation between CLDN16 and CLDN19 in unpolarized epithelial cells.

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Cotrafficking and coimmunoprecipitation between CLDN16 and CLDN19 in unp...
(A) Confocal images showing subcellular localization of CLDN19, CLDN16, and CLDN16-R149L mutant in LLC-PK1 cells. CLDN19 localized to the plasma membrane (arrow) and the endosomes and lysosomes (arrowheads), CLDN16 localized to the plasma membrane (red arrows); and CLDN16-R149L was confined to the ER. In the middle panel, the white arrow denotes a site of cell-cell interaction. (B) Coexpression of CLDN16 with CLDN19 in LLC-PK1 cells altered the subcellular localization of CLDN16. Notably, CLDN16 was recruited to the endosomes and lysosomes (arrowhead), where colocalization with CLDN19 occurred. CLDN16 and CLDN19 colocalization was also found at the cell-cell interaction (arrow). (C) The confinement of CLDN16-R149L mutant to the ER was not affected by CLDN19 coexpression. No colocalization was found between CLDN16-R149L and CLDN19. (D) Coimmunoprecipitation of CLDN16 and CLDN19 cotransfected in HEK293 cells. Input lane shows 10% of input amount. Antibodies used for coimmunoprecipitation are shown above the lanes; antibody for blot visualization is shown at left. Scale bars: 10 μm.