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

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.
Mesh Terms:
Amino Acid Sequence, Animals, Autophagy, Carrier Proteins, Conserved Sequence, HEK293 Cells, Host-Pathogen Interactions, Humans, Intracellular Membranes, Membrane Proteins, Mice, Microtubule-Associated Proteins, Molecular Sequence Data, Phagocytosis, Phagosomes, Phosphatidylinositol Phosphates, Protein Binding, Protein Interaction Domains and Motifs, Protein Isoforms, Protein Processing, Post-Translational, Protein Transport, Salmonella typhimurium, Small Ubiquitin-Related Modifier Proteins
Mol. Cell
Date: Jul. 17, 2014
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