Multiphasic dynamics of phosphatidylinositol 4-phosphate during phagocytosis

Mol Biol Cell. 2017 Jan 1;28(1):128-140. doi: 10.1091/mbc.E16-06-0451. Epub 2016 Nov 9.

Abstract

We analyzed the distribution, fate, and functional role of phosphatidylinositol 4-phosphate (PtdIns4P) during phagosome formation and maturation. To this end, we used genetically encoded probes consisting of the PtdIns4P-binding domain of the bacterial effector SidM. PtdIns4P was found to undergo complex, multiphasic changes during phagocytosis. The phosphoinositide, which is present in the plasmalemma before engagement of the target particle, is transiently enriched in the phagosomal cup. Soon after the phagosome seals, PtdIns4P levels drop precipitously due to the hydrolytic activity of Sac2 and phospholipase C, becoming undetectable for ∼10 min. PtdIns4P disappearance coincides with the emergence of phagosomal PtdIns3P. Conversely, the disappearance of PtdIns3P that signals the transition from early to late phagosomes is accompanied by resurgence of PtdIns4P, which is associated with the recruitment of phosphatidylinositol 4-kinase 2A. The reacquisition of PtdIns4P can be prevented by silencing expression of the kinase and can be counteracted by recruitment of a 4-phosphatase with a heterodimerization system. Using these approaches, we found that the secondary accumulation of PtdIns4P is required for proper phagosomal acidification. Defective acidification may be caused by impaired recruitment of Rab7 effectors, including RILP, which were shown earlier to displace phagosomes toward perinuclear lysosomes. Our results show multimodal dynamics of PtdIns4P during phagocytosis and suggest that the phosphoinositide plays important roles during the maturation of the phagosome.

Publication types

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

MeSH terms

  • 1-Phosphatidylinositol 4-Kinase / metabolism
  • Animals
  • Endosomes / metabolism
  • Lysosomes / metabolism
  • Macrophages / metabolism
  • Mice
  • Minor Histocompatibility Antigens / metabolism
  • Phagocytosis / physiology
  • Phagosomes / metabolism*
  • Phagosomes / physiology
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphatidylinositol Phosphates / genetics
  • Phosphatidylinositol Phosphates / metabolism*
  • Phosphatidylinositol Phosphates / physiology*
  • Phosphotransferases (Alcohol Group Acceptor) / metabolism
  • RAW 264.7 Cells
  • rab GTP-Binding Proteins / metabolism

Substances

  • Minor Histocompatibility Antigens
  • Phosphatidylinositol Phosphates
  • phosphatidylinositol 3-phosphate
  • phosphatidylinositol 4-phosphate
  • Phosphatidylinositol 3-Kinases
  • Phosphotransferases (Alcohol Group Acceptor)
  • 1-Phosphatidylinositol 4-Kinase
  • PI4KIIIalpha protein, human
  • phosphatidylinositol phosphate 4-kinase
  • rab GTP-Binding Proteins