Fig. 1: The absence of BECLIN1, but not ATG7, leads to fatal loss of intestinal homeostasis.
a Intestinal epithelium-specific deletion of loxP-flanked Becn1 or Atg7 in adult mice is mediated by tamoxifen-inducible Cre recombinase from the villin 1 promoter. b Deletion of either BECLIN1 or ATG7 leads to defective autophagy as indicated by increased levels of total p62 and LC3, or increased LC3-I relative to LC3-II. Representative images of c abdominal necropsy and d intestinal tracts demonstrating the severe intestinal disruption seen only in the absence of BECLIN1 (upper: colon; lower: small intestine). e Intestinal lengths of mice at endpoint. f Body weight of mice over time normalized to day 0. g FFPE sections of mouse intestines, stained with H&E, reveal the extensive loss of the characteristic villus-crypt structures of the small intestines from Becn1ΔIEC mice. h Scoring of intestinal morphological integrity. i Loss of intestinal homeostasis in the absence of BECLIN but not ATG7 leads to increased mucosal and/or submucosal immune cell infiltration. j There was evidence of increased apoptosis, as determined by cleaved caspase-3 (CC3) and terminal doxynucleotidyl transferase dUTP nick-end labeling (TUNEL) staining, along the crypt-villus axis in Becn1ΔIEC mice only. k Loss of BECLIN1 results in loss of intestinal barrier integrity, leading to increased permeability to FITC-Dextran. For all data represented, except for the histology images, at least n = 6 biologically independent mice of each genotype were used. For the histology images, at least n = 4 biologically independent mice per genotype was used. Data represent n = 3 independent experiments unless otherwise indicated. Graphs show the mean ± S.E.M, except for the small intestinal lengths and body weight graphs, which show the mean ± S.D. Significance was determined by Welch’s unpaired t test. ns not significant (p > 0.05). Stom stomach, Duo duodenum, Jej jejunum, Ile ileum, Col colon, SI small intestine.
