Control of NOD2 and Rip2-dependent innate immune activation by GEF-H1.
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Zhao Y, Alonso C, Ballester I, Song JH, Chang SY, Guleng B, Arihiro S, Murray PJ, Xavier R, Kobayashi KS, Reinecker HC
Control of NOD2 and Rip2-dependent innate immune activation by GEF-H1.
Inflamm Bowel Dis. 2012 Apr;18(4):603-12. doi: 10.1002/ibd.21851. Epub 2011 Sep 1.
- PubMed ID
- 21887730 [ View in PubMed]
- Abstract
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-kappaB-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-kappaB 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.