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Abstract: FR-PO538

Exposure of Junctional Claudin-3 Epitopes in the Thick Ascending Limb of Cldn19-Deficient Mice

Session Information

Category: Fluid, Electrolytes, and Acid-Base Disorders

  • 1101 Fluid, Electrolyte, and Acid-Base Disorders: Basic

Authors

  • Dimke, Henrik, Syddansk Universitet, Odense, Syddanmark, Denmark
  • Houillier, Pascal, Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université Paris Cité, Paris, Paris, France
  • Prot-Bertoye, Caroline, Centre de Recherche des Cordeliers, INSERM, Sorbonne Université, Université Paris Cité, Paris, Paris, France
Background

The kidney plays a vital role in maintaining mineral balance. The reabsorption of calcium and magnesium in the renal thick ascending limb (TAL) is facilitated by CLDN16 and CLDN19 and mutations in either gene results in severe calcium and magnesium loss. Cldn3 is also expressed in TAL RNAseq databases, however some but not all studies localize the CLDN3 protein to the TAL. In our hands, using 3 distinct antibodies, we have been unable to detect CLDN3 expression in the TAL.

Methods

The pattern of expression of CLDN3 was evaluated using 3 distinct CLDN3 antibodies: 1. Anti-CLDN3 antibody (HPA014361 Sigma-Aldrich), 2. Anti-CLDN3 antibody (STJ23159, St John’s Laboratory), and 3. Anti-CLDN3 Antibody (34-1700, Invitrogen), all produced in rabbit. Using these antibodies, we investigated the localization of CLDN3 in the kidneys of both wild-type and Cldn19 deficient mice on 2 um paraffin sections.

Results

All antibodies showed immunoreactivity towards epitopes situated in the tight junctions of the renal tubular cells. In addition, the Sigma antibody labeled epitopes in the intercalated cells and the Invitrogen labelled epitopes in the perinuclear region of epithelial cells. With respect to the tight junction, CLDN3 was expressed in portions of the proximal tubule as well as distal nephron cells but was absent from the TAL in wild-type animals using all three antibodies. In contrast, in Cldn19 deficient animals, immunoreactivity was also found in the TAL in a mosaic pattern.

Conclusion

These findings suggest that CLDN3 localizes to the TAL where it may play a direct role in determining the permeability. Why immunoreactivity in the TAL is only seen in Cldn19 deficient animals remains to be elucidated. The findings could suggest that CLDN19 shields the epitope towards which CLDN3 binds in fixed tissue.

Funding

  • Private Foundation Support