WIPI2 links LC3 conjugation with PI3P, autophagosome formation, and pathogen clearance by recruiting Atg12-5-16L1

Mol Cell. 2014 Jul 17;55(2):238-52. doi: 10.1016/j.molcel.2014.05.021. Epub 2014 Jun 19.

Abstract

Mammalian cell homeostasis during starvation depends on initiation of autophagy by endoplasmic reticulum-localized phosphatidylinositol 3-phosphate (PtdIns(3)P) synthesis. Formation of double-membrane autophagosomes that engulf cytosolic components requires the LC3-conjugating Atg12-5-16L1 complex. The molecular mechanisms of Atg12-5-16L1 recruitment and significance of PtdIns(3)P synthesis at autophagosome formation sites are unknown. By identifying interacting partners of WIPIs, WD-repeat PtdIns(3)P effector proteins, we found that Atg16L1 directly binds WIPI2b. Mutation experiments and ectopic localization of WIPI2b to plasma membrane show that WIPI2b is a PtdIns(3)P effector upstream of Atg16L1 and is required for LC3 conjugation and starvation-induced autophagy through recruitment of the Atg12-5-16L1 complex. Atg16L1 mutants, which do not bind WIPI2b but bind FIP200, cannot rescue starvation-induced autophagy in Atg16L1-deficient MEFs. WIPI2b is also required for autophagic clearance of pathogenic bacteria. WIPI2b binds the membrane surrounding Salmonella and recruits the Atg12-5-16L1 complex, initiating LC3 conjugation, autophagosomal membrane formation, and engulfment of Salmonella.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Autophagy
  • Autophagy-Related Protein 12
  • Autophagy-Related Protein 5
  • Autophagy-Related Proteins
  • Carrier Proteins / chemistry
  • Carrier Proteins / metabolism
  • Carrier Proteins / physiology*
  • Conserved Sequence
  • HEK293 Cells
  • Host-Pathogen Interactions
  • Humans
  • Intracellular Membranes / metabolism
  • Membrane Proteins / physiology*
  • Mice
  • Microtubule-Associated Proteins / metabolism*
  • Molecular Sequence Data
  • Phagocytosis
  • Phagosomes / metabolism*
  • Phagosomes / microbiology
  • Phosphate-Binding Proteins
  • Phosphatidylinositol Phosphates / metabolism*
  • Protein Binding
  • Protein Interaction Domains and Motifs
  • Protein Isoforms / physiology
  • Protein Processing, Post-Translational
  • Protein Transport
  • Salmonella typhimurium / physiology*
  • Small Ubiquitin-Related Modifier Proteins / metabolism

Substances

  • ATG12 protein, human
  • ATG16L1 protein, human
  • ATG5 protein, human
  • Autophagy-Related Protein 12
  • Autophagy-Related Protein 5
  • Autophagy-Related Proteins
  • Carrier Proteins
  • Membrane Proteins
  • Microtubule-Associated Proteins
  • Phosphate-Binding Proteins
  • Phosphatidylinositol Phosphates
  • Protein Isoforms
  • Small Ubiquitin-Related Modifier Proteins
  • WIPI-2 protein, human
  • light chain 3, human
  • phosphatidylinositol 3-phosphate