A Crohn's Disease Variant in Atg16l1 Enhances Its Degradation by Caspase 3

Nature. 2014 Feb 27;506(7489):456-62. doi: 10.1038/nature13044. Epub 2014 Feb 19.

Abstract

Crohn's disease is a debilitating inflammatory bowel disease (IBD) that can involve the entire digestive tract. A single-nucleotide polymorphism (SNP) encoding a missense variant in the autophagy gene ATG16L1 (rs2241880, Thr300Ala) is strongly associated with the incidence of Crohn's disease. Numerous studies have demonstrated the effect of ATG16L1 deletion or deficiency; however, the molecular consequences of the Thr300Ala (T300A) variant remains unknown. Here we show that amino acids 296-299 constitute a caspase cleavage motif in ATG16L1 and that the T300A variant (T316A in mice) significantly increases ATG16L1 sensitization to caspase-3-mediated processing. We observed that death-receptor activation or starvation-induced metabolic stress in human and murine macrophages increased degradation of the T300A or T316A variants of ATG16L1, respectively, resulting in diminished autophagy. Knock-in mice harbouring the T316A variant showed defective clearance of the ileal pathogen Yersinia enterocolitica and an elevated inflammatory cytokine response. In turn, deletion of the caspase-3-encoding gene, Casp3, or elimination of the caspase cleavage site by site-directed mutagenesis rescued starvation-induced autophagy and pathogen clearance, respectively. These findings demonstrate that caspase 3 activation in the presence of a common risk allele leads to accelerated degradation of ATG16L1, placing cellular stress, apoptotic stimuli and impaired autophagy in a unified pathway that predisposes to Crohn's disease.

MeSH terms

  • Amino Acid Motifs
  • Animals
  • Autophagy / genetics
  • Autophagy-Related Proteins
  • Carrier Proteins / chemistry
  • Carrier Proteins / genetics*
  • Carrier Proteins / metabolism*
  • Caspase 3 / deficiency
  • Caspase 3 / genetics
  • Caspase 3 / metabolism*
  • Cell Line
  • Cells, Cultured
  • Crohn Disease / genetics*
  • Crohn Disease / pathology
  • Cytokines / immunology
  • Enzyme Activation
  • Female
  • Food Deprivation
  • Humans
  • Macrophages / immunology
  • Macrophages / metabolism
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Mutagenesis, Site-Directed
  • Polymorphism, Single Nucleotide / genetics*
  • Proteolysis*
  • Stress, Physiological
  • Yersinia enterocolitica / immunology

Substances

  • ATG16L1 protein, human
  • Autophagy-Related Proteins
  • Carrier Proteins
  • Cytokines
  • CASP3 protein, human
  • Caspase 3