Proinflammatory cytokine-induced Tight Junction remodeling through dynamic self-assembly of claudins

Tight Junctions (TJs) are dynamic, mutiprotein intercellular adhesive contacts that provide a vital barrier function in epithelial tissues. TJs are remodeled during physiologic development and pathologic mucosal inflammation, and differential expression of the claudin family of TJ proteins determines epithelial barrier properties. However, the molecular mechanisms involved in TJ remodeling are incompletely understood. Using acGFP-claudin 4 as a bio-sensor of TJ remodeling, we observed increased claudin 4 Fluorescence Recovery after Photobleaching (FRAP) dynamics in response to inflammatory cytokines. Interferon gamma (IFN- and Tumor Necrosis Factor alpha (TNF– increased the proportion of mobile claudin 4 in the TJ. Upregulation of claudin 4 protein rescued these mobility defects and cytokine-induced barrier compromise. Furthermore, claudins 2 and 4 have reciprocal effects on epithelial barrier function, exhibit differential FRAP dynamics, and compete for residency within the TJ. These findings establish a model of TJs as self-assembling systems that undergo remodeling in response to proinflammatory cytokines through a mechanism of heterotypic claudin binding incompatibility.