PAK1 modulates a PPARγ/NF-κB cascade in intestinal inflammation

Dammann, K; Khare, V; Lang, M; Claudel, T; Harpain, F; Granofszky, N; Evstatiev, R; Williams, J M; Pritchard, D M; Watson, A; Gasche, C

Abstract

P21-activated kinases (PAKs) are multifunctional effectors of Rho GTPases with both kinase and scaffolding activity. Here, we investigated the effects of inflammation on PAK1 signaling and its role in colitis-driven carcinogenesis. PAK1 and p-PAK1 (Thr423) were assessed by immunohistochemistry, immunofluorescence, and Western blot. C57BL6/J wildtype mice were treated with a single intraperitoneal TNFα injection. Small intestinal organoids from these mice and from PAK1-KO mice were cultured with TNFα. NF-κB and PPARγ were analyzed upon PAK1 overexpression and silencing for transcriptional/translational regulation. PAK1 expression and activation was increased on the luminal intestinal epithelial surface in inflammatory bowel disease and colitis-associated cancer. PAK1 was phosphorylated upon treatment with IFNγ, IL-1β, and TNFα. In vivo, mice administered with TNFα showed increased p-PAK1 in intestinal villi, which was associated with nuclear p65 and NF-κB activation. p65 nuclear translocation downstream of TNFα was strongly inhibited in PAK1-KO small intestinal organoids. PAK1 overexpression induced a PAK1–p65 interaction as visualized by co-immunoprecipitation, nuclear translocation, and increased NF-κB transactivation, all of which were impeded by kinase-dead PAK1. Moreover, PAK1 overexpression downregulated PPARγ and mesalamine recovered PPARγ through PAK1 inhibition. On the other hand PAK1 silencing inhibited NF-κB, which was recovered using BADGE, a PPARγ antagonist. Altogether these data demonstrate that PAK1 overexpression and activation in inflammation and colitis-associated cancer promote NF-κB activity via suppression of PPARγ in intestinal epithelial cells.

Citation

Dammann, K., Khare, V., Lang, M., Claudel, T., Harpain, F., Granofszky, N., …Gasche, C. (2015). PAK1 modulates a PPARγ/NF-κB cascade in intestinal inflammation. Biochimica et Biophysica Acta (BBA) - Molecular Cell Research, 1853(10A), 2349-2360. https://doi.org/10.1016/j.bbamcr.2015.05.031

• Journal Article Type: Article
• Acceptance Date: May 28, 2015
• Publication Date: May 31, 2015
• Deposit Date: Sep 6, 2018
• Publicly Available Date: Sep 6, 2018
• Journal: Biochimica et Biophysica Acta (BBA) - Molecular Cell Research
• Print ISSN: 0167-4889
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 1853
• Issue: 10A
• Pages: 2349-2360
• DOI: https://doi.org/10.1016/j.bbamcr.2015.05.031
• Public URL: https://rvc-repository.worktribe.com/output/1400675