Atg14 protects the intestinal epithelium from TNF-triggered villus atrophy.

ABSTRACT

Regulation of intestinal epithelial turnover is a key component of villus maintenance in the intestine. The balance of cell turnover can be perturbed by various extrinsic factors including the cytokine TNF, a cell signaling protein that mediates both proliferative and cytotoxic outcomes. Under conditions of infection and damage, defects in autophagy are associated with TNF-mediated cell death and tissue damage in the intestinal epithelium. However, a direct role of autophagy within the context of enterocyte cell death during homeostasis is lacking. Here, we generated mice lacking ATG14 (autophagy related 14) within the intestinal epithelium [Atg14f/f Vil1-Cre (VC)+]. These mice developed spontaneous villus loss and intestinal epithelial cell death within the small intestine. Based on marker studies, the increased cell death in these mice was due to apoptosis. Atg14f/f VC+ intestinal epithelial cells demonstrated sensitivity to TNF-triggered apoptosis. Correspondingly, both TNF blocking antibody and genetic deletion of Tnfrsf1a/Tnfr1 rescued villus loss and cell death phenotype in Atg14f/f VC+ mice. Lastly, we identified a similar pattern of spontaneous villus atrophy and cell death when Rb1cc1/Fip200 was conditionally deleted from the intestinal epithelium (Rb1cc1f/f VC+). Overall, these findings are consistent with the hypothesis that factors that control entry into the autophagy pathway are also required during homeostasis to prevent TNF triggered death in the intestine. Abbreviations ANOVA analysis of variance; Atg14 autophagy related 14; Atg16l1 autophagy related 16-like 1 (S. cerevisiae); Atg5 autophagy related 5; cCASP3 cleaved CASP3/caspase-3; cCASP8 cleaved CASP8/caspase-8; CHX cycloheximide; EdU 5-ethynyl-2´-deoxyuridine thymidine; f/f flox/flox; H&E hematoxylin and eosin; MTT 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; Nec-1 necrostatin-1; Rb1cc1/Fip200 RB1-inducible coiled-coil 1; Ripk1 receptor (TNFRSF)-interacting serine-threonine kinase 1; Ripk3 receptor (TNFRSF)-interacting serine-threonine kinase 3; Tnfrsf1a/Tnfr1 tumor necrosis factor receptor superfamily, member 1a; Tnf/ Tnfsf1a tumor necrosis factor; VC Vil1/villin 1-Cre.