Phosphatidylinositol-phosphates mediate cytoskeletal reorganization during phagocytosis via a unique modular protein consisting of RhoGEF/DH and FYVE domains in the parasitic protozoon Entamoeba histolytica

Cell Microbiol. 2009 Oct;11(10):1471-91. doi: 10.1111/j.1462-5822.2009.01341.x. Epub 2009 Jun 3.

Abstract

To understand the roles of phosphoinositides [PtdIns] in phagocytosis of parasitic eukaryotes, we examined the interaction of phosphatidylinositol-3-phosphate [PtdIns(3)P] and putative PtdIns-P-binding proteins during phagocytosis in the enteric protozoan parasite Entamoeba histolytica. It was previously shown that phagocytosis in E. histolytica is indispensable for virulence and is inhibited by PtdIns 3-kinase inhibitors. We demonstrated by time-lapse live imaging that during the initiation of phagocytosis, the PtdIns(3)P biomarker GFP-Hrs-FYVE, was translocated to the phagocytic cup, phagosome, and to tunnel-like structures connecting the plasma membrane and phagosomes. E. histolytica possesses 12 FYVE domain-containing proteins (EhFP1-12), 11 of which also contain the RhoGEF/DH domain. Among them EhFP4 was shown to be recruited to the tunnel-like structures and to the proximal region of the phagosome. We further demonstrated that EhFP4 physically interacted with 4 of 10 predominant Rho/Rac small GTPases. Phosphoinositide binding assay showed that EhFP4 unexpectedly bound to PtdIns(4)P via the carboxyl-terminal domain and that the FYVE domain modulates the binding specificity of EhFP4 to PtdIns-P. Expression of the FYVE domain from EhFP4 inhibited phagocytosis while enhancement was observed when mammalian Hrs-FYVE domain was expressed. Altogether, we demonstrated that PtdIns(3)P, PtdIns(4)P and EhFP4 coordinately regulate phagocytosis and phagosome maturation in this parasitic eukaryote.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Membrane / chemistry
  • Cytoskeletal Proteins / metabolism*
  • Entamoeba histolytica / physiology*
  • Guanine Nucleotide Exchange Factors / metabolism*
  • Microscopy, Video
  • Phagocytosis*
  • Phagosomes / chemistry
  • Phosphatidylinositol Phosphates / metabolism*
  • Protein Interaction Mapping
  • Protein Structure, Tertiary
  • Protozoan Proteins / metabolism*
  • Rho Guanine Nucleotide Exchange Factors

Substances

  • Cytoskeletal Proteins
  • Guanine Nucleotide Exchange Factors
  • Phosphatidylinositol Phosphates
  • Protozoan Proteins
  • Rho Guanine Nucleotide Exchange Factors