The Influence of Neddylation on the Mucosal Inflammatory Response

Abstract

Recent work has revealed a central role for neddylation (the conjugation of a Nedd8 protein to Cullin‐proteins) in the induction of the NF‐κB pathway (via Cullin‐1) and stabilization of hypoxia‐inducible factor (HIF, via Cullin‐2) during inflammatory responses. Our recent work indicated that pharmacological stabilization of HIF with the neddylation inhibitor MLN4924 significantly abrogated colitis endpoints in mice. In the present studies, we addressed the contribution of Cullin‐1 neddylation and NF‐kB signaling to mucosal inflammatory responses in vitro and in vivo. Initial in vitro studies using T84 intestinal epithelial cells revealed that MLN4924 prominently induces the deneddylation of Cullin‐1. Parallel western blot analysis and luciferase reporter assays revealed MLN4924 as a potent inhibitor of intestinal epithelial NF‐kB. In vivo administration of MLN4924 (3mg/kg/day) in a TNBS colitis model significantly increased disease severity. Indeed, MLN4924 resulted in increased weight loss and colon shortening as well as increased mortality early in the inflammatory response (day 2). Histologic analysis of the colon revealed that neddylation inhibition results in increased tissue damage and significantly increased mucosal apoptosis as determined by TUNEL staining, particularly within the epithelium. These studies reveal that Cullin‐1 neddylation, and most particularly NF‐κB signaling, is protective during mucosal inflammatory responses. We conclude that Cullin neddylation fine‐tunes the mucosal inflammatory response in vitro and in vivo.