1. PKC[eta] regulates occludin phosphorylation and epithelial tight junction integrity
- Author
-
Suzuki, Takuya, Elias, Bertha C., Seth, Ankur, Shen, Le, Turner, Jerrold R., Giorgianni, Francesco, Desiderio, Dominic, Guntaka, Ramareddy, and Rao, Radhakrishna
- Subjects
Protein kinases -- Properties ,Epithelium -- Properties ,Cell junctions -- Properties ,Phosphorylation -- Research ,Cellular control mechanisms -- Research ,Science and technology - Abstract
[PKC.sub.[eta]] is expressed predominantly in the epithelial tissues; however, its role in the regulation of epithelial tight junctions (TJs) is unknown. We present evidence that [PKC.sub.[eta]] 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 [PKC.sub.[eta]] by specific pseudo substrate inhibitor or knockdown of [PKC.sub.[eta]] by specific shRNA disrupts the junctional distribution of occludin and ZO-1 and compromises the epithelial barrier function. Expression of dominant negative, [PKC.sub.[eta]K394R] disrupts the TJ and barrier function, whereas wild-type [PKC.sub.[eta]] and constitutively active [PKC.sub.[eta]A161E] enhance the TJ integrity. Inhibition and knockdown of [PKC.sub.[eta]] or expression of [PKC.sub.[eta]K394R] induce dephosphorylation of occludin on threonine residues, whereas active PKC[eta] elevates occludin phosphorylation. [PKC.sub.[eta]] 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 [PKC.sub.[eta]] inhibitor-mediated redistribution of occludin from the intercellular junctions. These results reveal an important mechanism of epithelial TJ regulation by [PKC.sub.[eta]]. differentiation | epithelium | protein kinase
- Published
- 2009