Regulation of claudin/zonula occludens-1 complexes by hetero-claudin interactions

Barbara Schlingmann,Christopher T Capaldo,K Sabrina Lynn,Christian E Overgaard,Samuel A Molina,Michael Koval,Leslie A Mitchell,David M Guidot,Alexa L Mattheyses,Stevenclaude Dorsainvil White

doi:10.1038/ncomms12276

Barbara Schlingmann, Christopher T Capaldo + Show 8 more

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https://doi.org/10.1038/ncomms12276

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Abstract

Claudins are tetraspan transmembrane tight-junction proteins that regulate epithelial barriers. In the distal airspaces of the lung, alveolar epithelial tight junctions are crucial to regulate airspace fluid. Chronic alcohol abuse weakens alveolar tight junctions, priming the lung for acute respiratory distress syndrome, a frequently lethal condition caused by airspace flooding. Here we demonstrate that in response to alcohol, increased claudin-5 paradoxically accompanies an increase in paracellular leak and rearrangement of alveolar tight junctions. Claudin-5 is necessary and sufficient to diminish alveolar epithelial barrier function by impairing the ability of claudin-18 to interact with a scaffold protein, zonula occludens 1 (ZO-1), demonstrating that one claudin affects the ability of another claudin to interact with the tight-junction scaffold. Critically, a claudin-5 peptide mimetic reverses the deleterious effects of alcohol on alveolar barrier function. Thus, claudin controlled claudin-scaffold protein interactions are a novel target to regulate tight-junction permeability.

Highlights

Claudins are tetraspan transmembrane tight-junction proteins that regulate epithelial barriers
Using several complementary approaches, including super-resolution microscopy and the proximity ligation assay (PLA), we find that claudin-5 interacted with claudin-18, and that this decreases the ability of claudin-18 to productively interact with zonula occludens 1 (ZO-1)
As claudins are central to the regulation of tight-junction permeability[7,8,9], claudin protein composition of control- and alcohol-exposed alveolar epithelial cell (AEC) cultured on Transwell-permeable supports was examined by immunoblotting

Summary

Introduction

Claudins are tetraspan transmembrane tight-junction proteins that regulate epithelial barriers. Claudin-5 is necessary and sufficient to diminish alveolar epithelial barrier function by impairing the ability of claudin-18 to interact with a scaffold protein, zonula occludens 1 (ZO-1), demonstrating that one claudin affects the ability of another claudin to interact with the tight-junction scaffold. AECs from alcohol-fed animals have significant changes in tight-junction protein expression that are associated with a decrease in epithelial barrier function. Among these changes is an increase in claudin-5 expression. The appearance of tight-junction spikes correlates with increased paracellular leak between AECs. Using several complementary approaches, including super-resolution microscopy and the proximity ligation assay (PLA), we find that claudin-5 interacted with claudin-18, and that this decreases the ability of claudin-18 to productively interact with zonula occludens 1 (ZO-1). This mechanism is targetable using a claudin-5 mimetic peptide, suggesting a potential therapeutic approach to promote alveolar barrier function

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