The Atg16l1 gene: characterization of wild type, knock-in, and knock-out phenotypes in rats

Abstract

ATG16L1 is a ubiquitous autophagy gene responsible, in part, for formation of the double-membrane bound autophagosome that delivers unwanted cellular debris and intracellular pathogens to the lysosome for degradation. A single, nonsynonymous adenine to guanine polymorphism resulting in a threonine to alanine amino acid substitution (T300A) directly preceded by a caspase cleavage site (DxxD) causes an increased susceptibility to Crohn's disease (CD) in humans. The mechanism behind this increased susceptibility is still being elucidated, however, the amino acid change caused by this point mutation results in increased ATG16L1 protein sensitivity to caspase 3-mediated cleavage. In order to generate novel rat strains carrying genetic alterations in the rat Atg16l1 gene, we first characterized the wild type rat gene. We identified four alternative splice variants with tissue-specific expression. Using CRISPR-Cas9 genome editing technology, we developed a knock-in rat model for the human ATG16L1 T300A CD risk polymorphism as well as a knock-out rat model to evaluate the role of Atg16l1 in autophagy as well as its potential effect on CD susceptibility. These are the first reported rat strains with alterations of the Atg16l1 gene. Consistent with studies of the effects of human ATG16L1 polymorphisms, models exhibit morphological abnormalities in both Paneth and goblet cells, but do not develop spontaneous intestinal permeability or inflammatory bowel disease. Analysis of the gut microbiota does not show inherent differences in bacterial composition between wild type and genetically modified animals. These Atg16l1 strains are valuable new animal models for the study of both autophagy and CD susceptibility.

The relationship between extreme inter-individual variation in macrophage gene expression and genetic susceptibility to inflammatory bowel disease

“…Widely-expressed. Neighbouring INPP5D (SHIP1) gene high in monocytes, down-regulated by CSF1 Chesney et al ( 2021 ), Fernandes et al ( 2018 ) SLC39A8 Zinc transporter (ZIP8) Monocyte/macrophage specific. Highly-inducible by LPS Note adjacent NFKB1 , also inducible by LPS.…”

Research progress on the relationship between Paneth cells-susceptibility genes, intestinal microecology and inflammatory bowel disease

“…However, an anti-TL1A antibody could block TL1A function, reverse colonic fibrosis, and reduce existing colonic inflammation. Therefore, overexpression of TL1A can aggravate proximal intestinal inflammation and fibrous stenosis and promote disease progression[ 131 ].…”

Genetic and Epigenetic Etiology of Inflammatory Bowel Disease: An Update

“…Epigenetics deals with the study of mechanisms that affect hereditary changes in phenotype, regardless of the DNA sequence [ 54 ]. It probably plays a role in the pathogenesis of IBD, as certain environmental factors can influence the risk of developing IBD through epigenetic modifications, such as DNA methylation, post-translational modifications of histones, and the expression of noncoding RNAs [ 159 ].…”

“…ATG16L1 mice show morphological abnormalities in Paneth and cup cells, but do not develop intestinal autophagy or inflammatory bowel disease [ 54 ].…”