title: Non-apoptotic role of BID in inflammation and innate immunity.
abstract: Innate immunity is a fundamental defence response that depends on evolutionarily conserved pattern recognition receptors for sensing infections or danger signals. Nucleotide-binding and oligomerization domain (NOD) proteins are cytosolic pattern-recognition receptors of paramount importance in the intestine, and their dysregulation is associated with inflammatory bowel disease. They sense peptidoglycans from commensal microorganisms and pathogens and coordinate signalling events that culminate in the induction of inflammation and anti-microbial responses. However, the signalling mechanisms involved in this process are not fully understood. Here, using genome-wide RNA interference, we identify candidate genes that modulate the NOD1 inflammatory response in intestinal epithelial cells. Our results reveal a significant crosstalk between innate immunity and apoptosis and identify BID, a BCL2 family protein, as a critical component of the inflammatory response. Colonocytes depleted of BID or macrophages from Bid(-/-) mice are markedly defective in cytokine production in response to NOD activation. Furthermore, Bid(-/-) mice are unresponsive to local or systemic exposure to NOD agonists or their protective effect in experimental colitis. Mechanistically, BID interacts with NOD1, NOD2 and the IκB kinase (IKK) complex, impacting NF-κB and extracellular signal-regulated kinase (ERK) signalling. Our results define a novel role of BID in inflammation and immunity independent of its apoptotic function, furthering the mounting evidence of evolutionary conservation between the mechanisms of apoptosis and immunity.
authors.affiliation: Department of Medicine, McGill University, Montreal, Quebec H3G 0B1, Canada.
authors.forename: Garabet
authors.initials: G
authors.lastname: Yeretssian
authors.forename: Ricardo G
authors.initials: RG
authors.lastname: Correa
authors.forename: Karine
authors.initials: K
authors.lastname: Doiron
authors.forename: Patrick
authors.initials: P
authors.lastname: Fitzgerald
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Dillon
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Green
authors.forename: John C
authors.initials: JC
authors.lastname: Reed
authors.forename: Maya
authors.initials: M
authors.lastname: Saleh
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000276:immunology; D051023:BH3 Interacting Domain Death Agonist Protein / Q000235:genetics / Q000276:immunology*; D003092:Colitis / Q000235:genetics / Q000276:immunology; D004847:Epithelial Cells / Q000276:immunology*; D057809:HEK293 Cells; D019073:HT29 Cells; D006801:Humans; D051550:I-kappa B Kinase / Q000276:immunology; D007113:Immunity, Innate / Q000235:genetics*; D007249:Inflammation / Q000235:genetics*; D007413:Intestinal Mucosa / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D053474:Nod1 Signaling Adaptor Protein / Q000276:immunology; D053473:Nod2 Signaling Adaptor Protein / Q000276:immunology; D034622:RNA Interference; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology
chemical_list: D051023:BH3 Interacting Domain Death Agonist Protein; D053474:Nod1 Signaling Adaptor Protein; C507873:Nod1 protein, mouse; D053473:Nod2 Signaling Adaptor Protein; C495945:Nod2 protein, mouse; D051550:I-kappa B Kinase