Project description:Susceptibility to Crohn's disease, a complex inflammatory disease involving the small intestine, is controlled by over 30 loci. One Crohn's disease risk allele is in ATG16L1, a gene homologous to the essential yeast autophagy gene ATG16 (ref. 2). It is not known how ATG16L1 or autophagy contributes to intestinal biology or Crohn's disease pathogenesis. To address these questions, we generated and characterized mice that are hypomorphic for ATG16L1 protein expression, and validated conclusions on the basis of studies in these mice by analysing intestinal tissues that we collected from Crohn's disease patients carrying the Crohn's disease risk allele of ATG16L1. Here we show that ATG16L1 is a bona fide autophagy protein. Within the ileal epithelium, both ATG16L1 and a second essential autophagy protein ATG5 are selectively important for the biology of the Paneth cell, a specialized epithelial cell that functions in part by secretion of granule contents containing antimicrobial peptides and other proteins that alter the intestinal environment. ATG16L1- and ATG5-deficient Paneth cells exhibited notable abnormalities in the granule exocytosis pathway. In addition, transcriptional analysis revealed an unexpected gain of function specific to ATG16L1-deficient Paneth cells including increased expression of genes involved in peroxisome proliferator-activated receptor (PPAR) signalling and lipid metabolism, of acute phase reactants and of two adipocytokines, leptin and adiponectin, known to directly influence intestinal injury responses. Importantly, Crohn's disease patients homozygous for the ATG16L1 Crohn's disease risk allele displayed Paneth cell granule abnormalities similar to those observed in autophagy-protein-deficient mice and expressed increased levels of leptin protein. Thus, ATG16L1, and probably the process of autophagy, have a role within the intestinal epithelium of mice and Crohn's disease patients by selective effects on the cell biology and specialized regulatory properties of Paneth cells. Experiment Overall Design: 4 Samples: 2 replicates of Atg16-hypomorph Paneth cells and 2 replicates of Wildtype Paneth cells.

Project description:Crohn’s disease (CD) is associated with multiple Paneth cell dysfunctions such as altered antimicrobial secretion that relies on autophagy - an essential process controlling the turnover of cellular components. Genome-wide association studies have linked CD to mutations in the ATG16l1 gene, encoding an important component of the autophagy machinery. Patients carrying the ATG16l1 CD risk allele have Paneth cell abnormalities, as reproduced in Atg16l1-deficient mouse models. However, the direct effect of the ATG16L1-deficiency and autophagy-impairment in Paneth cells has not been analysed in detail. To investigate this, we generated a mouse model lacking ATG16L1 specifically in intestinal epithelial cells (Atg16l1△IEC) making these cells impaired in autophagy. Using a 3D small intestinal organoid culture model, which we enriched for Paneth cells and compared the proteomic profiles of organoids derived from the wild-type (WT) and the Atg16l1△IEC mice. We used an integrated computational approach combining protein-protein interaction networks, list of proteins potentially targeted by autophagy and functional information on the proteins with altered protein levels to identify the mechanistic link between autophagy-impairment and disrupted cellular process. 198 (70%) of the 284 altered proteins were more abundant in autophagy-impaired organoids than WT organoids that could be due to a reduced protein turnover. Combining the proteomic dataset with the potential target proteins of selective autophagy proteins revealed that 116 (41%) of the differentially abundant proteins could rely on autophagy-mediated turnover. Taken together, our results suggest that proteins with increased levels in autophagy-impaired background require an autophagy-mediated turnover mechanism, and that their altered levels in CD could affect key cellular processes. Consequently, we pointed out the importance of autophagy in controlling the turnover of proteins relevant in key Paneth cell functions such as exocytosis, apoptosis and DNA damage repair. Our study unravels autophagy-dependent cellular processes of Paneth cells that not directly relies on the autophagy process, rather than a selective protein turnover mechanism. The identified proteins and processes open new avenues for targeted, cell type-specific therapeutic interventions in CD.

Project description:Susceptibility to Crohn's disease, a complex inflammatory disease involving the small intestine, is controlled by over 30 loci. One Crohn's disease risk allele is in ATG16L1, a gene homologous to the essential yeast autophagy gene ATG16 (ref. 2). It is not known how ATG16L1 or autophagy contributes to intestinal biology or Crohn's disease pathogenesis. To address these questions, we generated and characterized mice that are hypomorphic for ATG16L1 protein expression, and validated conclusions on the basis of studies in these mice by analysing intestinal tissues that we collected from Crohn's disease patients carrying the Crohn's disease risk allele of ATG16L1. Here we show that ATG16L1 is a bona fide autophagy protein. Within the ileal epithelium, both ATG16L1 and a second essential autophagy protein ATG5 are selectively important for the biology of the Paneth cell, a specialized epithelial cell that functions in part by secretion of granule contents containing antimicrobial peptides and other proteins that alter the intestinal environment. ATG16L1- and ATG5-deficient Paneth cells exhibited notable abnormalities in the granule exocytosis pathway. In addition, transcriptional analysis revealed an unexpected gain of function specific to ATG16L1-deficient Paneth cells including increased expression of genes involved in peroxisome proliferator-activated receptor (PPAR) signalling and lipid metabolism, of acute phase reactants and of two adipocytokines, leptin and adiponectin, known to directly influence intestinal injury responses. Importantly, Crohn's disease patients homozygous for the ATG16L1 Crohn's disease risk allele displayed Paneth cell granule abnormalities similar to those observed in autophagy-protein-deficient mice and expressed increased levels of leptin protein. Thus, ATG16L1, and probably the process of autophagy, have a role within the intestinal epithelium of mice and Crohn's disease patients by selective effects on the cell biology and specialized regulatory properties of Paneth cells.

Dataset Information

Distinct tissue-specific roles for the disease-associated autophagy genes ATG16L2 and ATG16L1

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