Molecular Characterization of LC3-associated Phagocytosis Reveals Distinct Roles for Rubicon, NOX2 and Autophagy Proteins

Nat Cell Biol. 2015 Jul;17(7):893-906. doi: 10.1038/ncb3192. Epub 2015 Jun 22.

Abstract

LC3-associated phagocytosis (LAP) is a process wherein elements of autophagy conjugate LC3 to phagosomal membranes. We characterize the molecular requirements for LAP, and identify Rubicon as being required for LAP but not autophagy. Rubicon is recruited to LAPosomes and is required for the activity of a Class III PI(3)K complex containing UVRAG but lacking ATG14 and Ambra1. This allows for the sustained localization of PtdIns(3)P, which is critical for recruitment of downstream autophagic proteins and stabilization of the NOX2 complex to produce reactive oxygen species. Both PtdIns(3)P and reactive oxygen species are required for conjugation of LC3 to LAPosomes and subsequent association with LAMP1(+) lysosomes. LAP is induced by engulfment of Aspergillus fumigatus, a fungal pathogen that commonly afflicts immunocompromised hosts, and is required for its optimal clearance in vivo. Therefore, we have identified molecules that distinguish LAP from canonical autophagy, thereby elucidating the importance of LAP in response to A. fumigatus infection.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aspergillus fumigatus / physiology
  • Autophagy*
  • Autophagy-Related Proteins
  • Cell Line
  • Class III Phosphatidylinositol 3-Kinases / metabolism
  • Female
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Host-Pathogen Interactions
  • Immunoblotting
  • Intracellular Signaling Peptides and Proteins / genetics
  • Intracellular Signaling Peptides and Proteins / metabolism*
  • Macrophages / metabolism
  • Macrophages / microbiology
  • Male
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism*
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mice, Transgenic
  • Microscopy, Confocal
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism*
  • NADPH Oxidase 2
  • NADPH Oxidases / genetics
  • NADPH Oxidases / metabolism*
  • Phagocytosis*
  • Phagosomes / metabolism
  • Phagosomes / microbiology
  • Phosphatidylinositol Phosphates / metabolism
  • RNA Interference
  • Reactive Oxygen Species / metabolism
  • Tumor Suppressor Proteins / genetics
  • Tumor Suppressor Proteins / metabolism
  • Vesicular Transport Proteins / genetics
  • Vesicular Transport Proteins / metabolism

Substances

  • Atg14 protein, mouse
  • Autophagy-Related Proteins
  • Intracellular Signaling Peptides and Proteins
  • MAP1LC3 protein, mouse
  • Membrane Glycoproteins
  • Microtubule-Associated Proteins
  • Phosphatidylinositol Phosphates
  • Reactive Oxygen Species
  • Tumor Suppressor Proteins
  • UVRAG protein, mouse
  • Vesicular Transport Proteins
  • rubicon protein, mouse
  • Green Fluorescent Proteins
  • Cybb protein, mouse
  • NADPH Oxidase 2
  • NADPH Oxidases
  • Class III Phosphatidylinositol 3-Kinases