title: Cellular inhibitors of apoptosis cIAP1 and cIAP2 are required for innate immunity signaling by the pattern recognition receptors NOD1 and NOD2.
abstract: Cellular inhibitor of apoptosis proteins (cIAPs) block apoptosis, but their physiological functions are still under investigation. Here, we report that cIAP1 and cIAP2 are E3 ubiquitin ligases that are required for receptor-interacting protein 2 (RIP2) ubiquitination and for nucleotide-binding and oligomerization (NOD) signaling. Macrophages derived from Birc2(-/-) or Birc3(-/-) mice, or colonocytes depleted of cIAP1 or cIAP2 by RNAi, were defective in NOD signaling and displayed sharp attenuation of cytokine and chemokine production. This blunted response was observed in vivo when Birc2(-/-) and Birc3(-/-) mice were challenged with NOD agonists. Defects in NOD2 signaling are associated with Crohn's disease, and muramyl dipeptide (MDP) activation of NOD2 signaling protects mice from experimental colitis. Here, we show that administration of MDP protected wild-type but not Ripk2(-/-) or Birc3(-/-) mice from colitis, confirming the role of the cIAPs in NOD2 signaling in vivo. This discovery provides therapeutic opportunities in the treatment of NOD-dependent immunologic and inflammatory diseases.
authors.affiliation: Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.
authors.forename: Mathieu J M
authors.initials: MJ
authors.lastname: Bertrand
authors.forename: Karine
authors.initials: K
authors.lastname: Doiron
authors.forename: Katherine
authors.initials: K
authors.lastname: Labbé
authors.forename: Robert G
authors.initials: RG
authors.lastname: Korneluk
authors.forename: Philip A
authors.initials: PA
authors.lastname: Barker
authors.forename: Maya
authors.initials: M
authors.lastname: Saleh
mesh_terms: D000119:Acetylmuramyl-Alanyl-Isoglutamine / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000276:immunology; D000075747:Baculoviral IAP Repeat-Containing 3 Protein; D003092:Colitis / Q000201:enzymology / Q000276:immunology / Q000473:pathology; D016207:Cytokines / Q000276:immunology / Q000378:metabolism; D007113:Immunity, Innate; D051034:Inhibitor of Apoptosis Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D053474:Nod1 Signaling Adaptor Protein / Q000819:agonists / Q000276:immunology / Q000378:metabolism*; D053473:Nod2 Signaling Adaptor Protein / Q000819:agonists / Q000276:immunology / Q000378:metabolism*; D053475:Receptor-Interacting Protein Serine-Threonine Kinase 2; D053422:Receptor-Interacting Protein Serine-Threonine Kinases / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D051192:Receptors, Pattern Recognition / Q000819:agonists / Q000276:immunology / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000276:immunology; D044767:Ubiquitin-Protein Ligases; D054875:Ubiquitination / Q000276:immunology
chemical_list: D016207:Cytokines; D051034:Inhibitor of Apoptosis Proteins; D053474:Nod1 Signaling Adaptor Protein; D053473:Nod2 Signaling Adaptor Protein; D051192:Receptors, Pattern Recognition; D000119:Acetylmuramyl-Alanyl-Isoglutamine; D000075747:Baculoviral IAP Repeat-Containing 3 Protein; C494834:Birc2 protein, mouse; C494835:Birc3 protein, mouse; D044767:Ubiquitin-Protein Ligases; D053475:Receptor-Interacting Protein Serine-Threonine Kinase 2; D053422:Receptor-Interacting Protein Serine-Threonine Kinases; C506255:Ripk2 protein, mouse