title: A Crohn's disease variant in Atg16l1 enhances its degradation by caspase 3.
abstract: Crohn's disease is a debilitating inflammatory bowel disease (IBD) that can involve the entire digestive tract. A single-nucleotide polymorphism (SNP) encoding a missense variant in the autophagy gene ATG16L1 (rs2241880, Thr300Ala) is strongly associated with the incidence of Crohn's disease. Numerous studies have demonstrated the effect of ATG16L1 deletion or deficiency; however, the molecular consequences of the Thr300Ala (T300A) variant remains unknown. Here we show that amino acids 296-299 constitute a caspase cleavage motif in ATG16L1 and that the T300A variant (T316A in mice) significantly increases ATG16L1 sensitization to caspase-3-mediated processing. We observed that death-receptor activation or starvation-induced metabolic stress in human and murine macrophages increased degradation of the T300A or T316A variants of ATG16L1, respectively, resulting in diminished autophagy. Knock-in mice harbouring the T316A variant showed defective clearance of the ileal pathogen Yersinia enterocolitica and an elevated inflammatory cytokine response. In turn, deletion of the caspase-3-encoding gene, Casp3, or elimination of the caspase cleavage site by site-directed mutagenesis rescued starvation-induced autophagy and pathogen clearance, respectively. These findings demonstrate that caspase 3 activation in the presence of a common risk allele leads to accelerated degradation of ATG16L1, placing cellular stress, apoptotic stimuli and impaired autophagy in a unified pathway that predisposes to Crohn's disease.
authors.affiliation: Department of Immunology, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, USA.
authors.forename: Aditya
authors.initials: A
authors.lastname: Murthy
authors.affiliation: Department of Immunology, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, USA.
authors.forename: Yun
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Immunology, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, USA.
authors.forename: Ivan
authors.initials: I
authors.lastname: Peng
authors.affiliation: Department of Pathology, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, USA.
authors.forename: Mike
authors.initials: M
authors.lastname: Reichelt
authors.affiliation: Department of Pathology, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, USA.
authors.forename: Anand Kumar
authors.initials: AK
authors.lastname: Katakam
authors.affiliation: Department of Immunology, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, USA.
authors.forename: Rajkumar
authors.initials: R
authors.lastname: Noubade
authors.affiliation: Department of Molecular Biology, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, USA.
authors.forename: Merone
authors.initials: M
authors.lastname: Roose-Girma
authors.affiliation: Department of Immunology, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, USA.
authors.forename: Jason
authors.initials: J
authors.lastname: DeVoss
authors.affiliation: Department of Pathology, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, USA.
authors.forename: Lauri
authors.initials: L
authors.lastname: Diehl
authors.affiliation: ITGR Human Genetics, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, USA.
authors.forename: Robert R
authors.initials: RR
authors.lastname: Graham
authors.affiliation: Department of Immunology, Genentech, Inc., 1 DNA Way, South San Francisco, California 94080, USA.
authors.forename: Menno
authors.initials: M
authors.lastname: van Lookeren Campagne
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D001343:Autophagy / Q000235:genetics; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D053148:Caspase 3 / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D002478:Cells, Cultured; D003424:Crohn Disease / Q000235:genetics* / Q000473:pathology; D016207:Cytokines / Q000276:immunology; D004789:Enzyme Activation; D005260:Female; D005508:Food Deprivation; D006801:Humans; D008264:Macrophages / Q000276:immunology / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D016297:Mutagenesis, Site-Directed; D020641:Polymorphism, Single Nucleotide / Q000235:genetics*; D059748:Proteolysis; D013312:Stress, Physiological; D015008:Yersinia enterocolitica / Q000276:immunology
chemical_list: C518959:ATG16L1 protein, human; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins; D016207:Cytokines; C505407:CASP3 protein, human; D053148:Caspase 3