Control of NOD2 and Rip2‐dependent innate immune activation by GEF‐H1
- Additional Document Info
- View All
BACKGROUND: Genetic variants of nucleotide-binding oligomerization domain 2 (NOD2) lead to aberrant microbial recognition and can cause chronic inflammatory diseases in patients with Crohn's disease (CD). METHODS: We utilized gene-specific siRNA mediated knockdown and expression of guanine nucleotide exchange factor H1 (GEF-H1) in wildtype, Rip2-, and Nod2-deficient macrophages, HCT-116 and HEK 293 cells to determine the role of GEF-H1 in NOD2 and Rip2-mediated NF-κB-dependent induction of proinflammatory cytokine expression. Confocal microscopy was used to determine subcellular distribution of GEF-H1, Rip2, and NOD2. RESULTS: We identified GEF-H1 as an unexpected component of innate immune regulation during microbial pattern recognition by NOD2. Surprisingly, GEF-H1-mediated the activation of Rip2 during signaling by NOD2, but not in the presence of the 3020 insC variant of NOD2 associated with CD. GEF-H1 functioned downstream of NOD2 as part of Rip2-containing signaling complexes and was responsible for phosphorylation of Rip2 by Src tyrosine kinase. Rip2 variants lacking the tyrosine target of GEF-H1-mediated phosphorylation were unable to mediate NF-κB activation in Rip2-deficient macrophages and failed to transduce NOD2 signaling. GEF-H1 is required downstream of NOD2 as part of Rip2-containing signaling complexes for the activation of innate immune responses. CONCLUSIONS: GEF-H1 connects tyrosine kinase function to NOD-like receptor signaling and is fundamental to the regulation of microbial recognition by ubiquitous innate immune mechanisms mediated by Rip2 kinase.
author list (cited authors)
Zhao, Y., Alonso, C., Ballester, I., Song, J. H., Chang, S. Y., Guleng, B., ... Reinecker, H.