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A coding polymorphism of human ATG16L1 (rs2241880; T300A) increases the risk of Crohn's disease and it has been shown to enhance susceptibility of ATG16L1 to caspase cleavage. Here we show that T300A also alters the ability of the C-terminal WD40-repeat domain of ATG16L1 to interact with an amino acid motif that recognizes this region. Such alteration impairs the unconventional autophagic activity of TMEM59, a transmembrane protein that contains the WD40 domain-binding motif, and disrupts its normal intracellular trafficking and its ability to engage ATG16L1 in response to bacterial infection. TMEM59-induced autophagy is blunted in cells expressing the fragments generated by caspase processing of the ATG16L1-T300A risk allele, whereas canonical autophagy remains unaffected. These results suggest that the T300A polymorphism alters the function of motif-containing molecules that engage ATG16L1 through the WD40 domain, either by influencing this interaction under non-stressful conditions or by inhibiting their downstream autophagic signalling after caspase-mediated cleavage. ; This work was funded by grants from the Ministerio de Ciencia e Innovación (Ref. SAF2011-23714) and the Ministerio de Economía y Competitividad (Ref. SAF2014-53320-R) of the Spanish Government, the Broad Medical Research Program at Crohn's and Colitis Foundation of America (CCFA; Ref. IBD-0369), the Junta de Castilla y León local government (Department of Education (Refs. CSI001A10-2, FIC016U14) and Department of Health (Ref. SAN11-FXP)) and the Fundación Solorzano (Refs. FS/1-2009 and FS/18-2014). R.J.X. is funded by the NIH (grants R01DK097485, P30DK043351 and U19AI109725) and the Helmsley Trust. Additional funding comes from the FEDER programme of the European Union. E.B.R. and I.S.G. are graduate students funded by predoctoral fellowships from the FPU programme (Ministerio de Educación, MEC, Spanish Government) and the Fundación Moraza, respectively. ; Peer Reviewed

To access publisher's full text version of this article, please click on the hyperlink in Additional Links field or click on the hyperlink at the top of the page marked Files. This article is open access. ; Protein-truncating variants protective against human disease provide in vivo validation of therapeutic targets. Here we used targeted sequencing to conduct a search for protein-truncating variants conferring protection against inflammatory bowel disease exploiting knowledge of common variants associated with the same disease. Through replication genotyping and imputation we found that a predicted protein-truncating variant (rs36095412, p.R179X, genotyped in 11,148 ulcerative colitis patients and 295,446 controls, MAF=up to 0.78%) in RNF186, a single-exon ring finger E3 ligase with strong colonic expression, protects against ulcerative colitis (overall P=6.89 × 10(-7), odds ratio=0.30). We further demonstrate that the truncated protein exhibits reduced expression and altered subcellular localization, suggesting the protective mechanism may reside in the loss of an interaction or function via mislocalization and/or loss of an essential transmembrane domain. ; National Institute of Diabetes and Digestive and Kidney Disease (NIDDK) DK064869 DK062432 National Human Genome Research Institute (NHGRI) DK064869 DK043351 HG005923 Crohns and Colitis Foundation 3765 Leona M. & Harry B. Helmsley Charitable Trust 2015PG-IBD001 Amgen 2013583217 CCFA 3765 Cedars-Sinai F. Widjaja Foundation, info:eu-repo/grantAgreement/EC/FP7/305479, European Union DK062413 AI067068 U54DE023789-01 Leona M. and Harry B. Helmsley Charitable Trust Crohn's and Colitis Foundation of America NIH DK062431 U01 DK062429 U01 DK062422 R01 DK092235 U01 DK062420 Medical Research Council, UK MR/J00314X/1 Wellcome Trust WT091310 098051 Inflammatory Bowel Disease Genetic Research Chair at the University of Pittsburgh PO1DK046763