Exophagy of annexin A2 via RAB11, RAB8A and RAB27A in IFN-γ-stimulated lung epithelial cells

Sci Rep. 2017 Jul 18;7(1):5676. doi: 10.1038/s41598-017-06076-4.

Abstract

Annexin A2 (ANXA2), a phospholipid-binding protein, has multiple biological functions depending on its cellular localization. We previously demonstrated that IFN-γ-triggered ANXA2 secretion is associated with exosomal release. Here, we show that IFN-γ-induced autophagy is essential for the extracellular secretion of ANXA2 in lung epithelial cells. We observed colocalization of ANXA2-containing autophagosomes with multivesicular bodies (MVBs) after IFN-γ stimulation, followed by exosomal release. IFN-γ-induced exophagic release of ANXA2 could not be observed in ATG5-silenced or mutant RAB11-expressing cells. Furthermore, knockdown of RAB8A and RAB27A, but not RAB27B, reduced IFN-γ-triggered ANXA2 secretion. Surface translocation of ANXA2 enhanced efferocytosis by epithelial cells, and inhibition of different exophagic steps, including autophagosome formation, fusion of autophagosomes with MVBs, and fusion of amphisomes with plasma membrane, reduced ANXA2-mediated efferocytosis. Our data reveal a novel route of IFN-γ-induced exophagy of ANXA2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • A549 Cells
  • Annexin A2 / metabolism*
  • Autophagy / physiology*
  • Epithelial Cells / drug effects
  • HEK293 Cells
  • Humans
  • Interferon-gamma / pharmacology*
  • Jurkat Cells
  • Lung / drug effects*
  • Multivesicular Bodies
  • Phagocytosis
  • rab GTP-Binding Proteins / metabolism
  • rab27 GTP-Binding Proteins / metabolism

Substances

  • Annexin A2
  • rab27 GTP-Binding Proteins
  • Interferon-gamma
  • rab11 protein
  • RAB27A protein, human
  • RAB8A protein, human
  • rab GTP-Binding Proteins