PKCη regulates occludin phosphorylation and epithelial tight junction integrity
- 6 January 2009
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 106 (1), 61-66
- https://doi.org/10.1073/pnas.0802741106
Abstract
PKCη is expressed predominantly in the epithelial tissues; however, its role in the regulation of epithelial tight junctions (TJs) is unknown. We present evidence that PKCη phosphorylates occludin on threonine residues (T403 and T404) and plays a crucial role in the assembly and/or maintenance of TJs in Caco-2 and MDCK cell monolayers. Inhibition of PKCη by specific pseudo substrate inhibitor or knockdown of PKCη by specific shRNA disrupts the junctional distribution of occludin and ZO-1 and compromises the epithelial barrier function. Expression of dominant negative, PKCηK394R disrupts the TJ and barrier function, whereas wild-type PKCη and constitutively active PKCηA161E enhance the TJ integrity. Inhibition and knockdown of PKCη or expression of PKCηK394R induce dephosphorylation of occludin on threonine residues, whereas active PKCη elevates occludin phosphorylation. PKCη directly interacts with the C-terminal domain of occludin and phosphorylates it on highly conserved T403 and T404. T403/404A mutations result in the loss of occludin's ability to localize at the TJs, whereas T403/404D mutations attenuates the PKCη inhibitor-mediated redistribution of occludin from the intercellular junctions. These results reveal an important mechanism of epithelial TJ regulation by PKCη.Keywords
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