Research ArticleInflammation

The E3 ubiquitin ligase Itch inhibits p38α signaling and skin inflammation through the ubiquitylation of Tab1

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Sci. Signal.  24 Feb 2015:
Vol. 8, Issue 365, pp. ra22
DOI: 10.1126/scisignal.2005903

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Deficiency in the E3 ubiquitin ligase Itch causes a skin-scratching phenotype in mice. We found that there was increased phosphorylation and activation of the mitogen-activated protein kinase p38α in spontaneous and experimentally induced skin lesions of Itch-deficient (Itch−/−) mice. Itch bound directly to the TGF-β–activated kinase 1–binding protein 1 (Tab1) through a conserved PPXY motif and inhibited the activation of p38α. Knockdown of Tab1 by short hairpin RNA attenuated the prolonged p38α phosphorylation exhibited by Itch−/− cells. Similarly, reconstitution of Itch−/− cells with wild-type Itch, but not the ligase-deficient Itch-C830A mutant, inhibited the phosphorylation and activation of p38α. Compared to the skin of wild-type mice, the skin of Itch−/− mice contained increased amounts of the mRNAs of proinflammatory cytokines, including tumor necrosis factor (TNF), interleukin-6 (IL-6), IL-1β, IL-11, and IL-19. Inhibition of p38 or blocking the interaction between p38α and Tab1 with a cell-permeable peptide substantially attenuated skin inflammation in Itch−/− mice. These findings provide insight into how Itch-mediated regulatory mechanisms prevent chronic skin inflammation, which could be exploited therapeutically.

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