A Genome-Wide siRNA Screen Reveals Positive and Negative Regulators of the NOD2 and NF-
B Signaling Pathways
Neil Warner1*,
Aaron Burberry1*,
Luigi Franchi1,
Yun-Gi Kim1,
Christine McDonald2,
Maureen A. Sartor3,4, and
Gabriel Núñez1,3
1 Department of Pathology, University of Michigan, Ann Arbor, MI 48109, USA.
2 Department of Pathobiology, Lerner Research Institute, The Cleveland Clinic, Cleveland, OH 44195, USA.
3 Comprehensive Cancer Center, University of Michigan, Ann Arbor, MI 48109, USA.
4 Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI 48109, USA.
* These authors contributed equally to this work.
Abstract:
The cytoplasmic receptor NOD2 (nucleotide-binding oligomerization domain 2) senses peptidoglycan fragments and triggers host defense pathways, including activation of nuclear factor 
B (NF-B) signaling, which lead to inflammatory immune responses. Dysregulation of NOD2 signaling is associated with inflammatory diseases, such as Crohn’s disease and Blau syndrome. We used a genome-wide small interfering RNA screen to identify regulators of the NOD2 signaling pathway. Several genes associated with Crohn’s disease risk were identified in the screen. A comparison of candidates from this screen with other "omics" data sets revealed interconnected networks of genes implicated in NF-B signaling, thus supporting a role for NOD2 and NF-B pathways in the pathogenesis of Crohn’s disease. Many of these regulators were validated in secondary assays, such as measurement of interleukin-8 secretion, which is partially dependent on NF-B. Knockdown of putative regulators in human embryonic kidney 293 cells followed by stimulation with tumor necrosis factor–α revealed that most of the genes identified were general regulators of NF-B signaling. Overall, the genes identified here provide a resource to facilitate the elucidation of the molecular mechanisms that regulate NOD2- and NF-B–mediated inflammation.
To whom correspondence should be addressed. E-mail: bclx{at}umich.edu
