Entamoeba histolytica: FYVE-finger domains, phosphatidylinositol 3-phosphate biosensors, associate with phagosomes but not fluid filled endosomes

• Published in: Experimental parasitology 2006-04, Vol.112 (4), p.221-231
• Main Authors: Powell, R.R., Welter, B.H., Hwu, R., Bowersox, B., Attaway, C., Temesvari, L.A.
• Format: Article
• Language: English
• Subjects: Adhesion; Amoeba; Androstadienes - pharmacology; Animals; Biological and medical sciences; Biosensing Techniques - methods; Blotting, Western; Chromones - pharmacology; dimethylsulfoxide; DMSO; early endosome antigen 1; EEA1; EhPAK; Electrophoresis, Polyacrylamide Gel; Endocytosis; Endosomes - physiology; Entamoeba histolytica; Entamoeba histolytica - physiology; Enzyme Inhibitors - pharmacology; Erythrocytes - immunology; faciogenital dysplasia protein 1; FBS; fetal bovine serum; FGD1; Fundamental and applied biological sciences. Psychology; FYVE-finger domain; Gal/GalNAc; galactose/ N-acetylgalactosamine; GFP; glutathione- S-transferase; green fluorescent protein; GST; hepatocyte growth factor-regulated kinase substrate; hRBCs; Hrs; human red blood cells; Humans; IPTG; isopropyl-β- d-thiogalactopyranoside; Life cycle. Host-agent relationship. Pathogenesis; LY 294002; Morpholines - pharmacology; p21-activated serine/threonine protein kinase; PBS; Phagocytosis; Phagocytosis - drug effects; Phagocytosis - physiology; Phagosomes - physiology; phosphate buffered saline; Phosphatidylinositol 3-kinase; Phosphatidylinositol 3-Kinases - antagonists & inhibitors; Phosphatidylinositol 3-Kinases - physiology; Phosphatidylinositol 3-phosphate; phosphatidylinositol bisphosphate; Phosphatidylinositol Phosphates - physiology; phosphatidylinositol triphosphate; PI 3-kinase; PI3P; Pinocytosis; PIP 2; PIP 3; plekstrin homology; Protozoa; Rho guanine nucleotide exchange factor; RhoGEF; Silver Staining; tetramethylrhodamine isothiocyanate; TRITC; Wortmannin
• ISSN: 0014-4894; 1090-2449
• DOI: 10.1016/j.exppara.2005.11.013

Endocytosis is an important virulence function for Entamoeba histolytica, the causative agent of amoebic dysentery. Although a number of E. histolytica proteins that regulate this process have been identified, less is known about the role of lipids. In other systems, phosphatidylinositol 3-phosphate (PI3P), a product of phosphatidylinositol 3-kinase (PI 3-kinase), has been shown to be required for endocytosis. FYVE-finger domains are protein motifs that bind specifically to PI3P. Using a PI3P biosensor consisting of glutathione- S-transferase (GST) fused to two tandem FYVE-finger domains, we have localized PI3P to phagosomes but not fluid-phase pinosomes in E. histolytica, suggesting a role for PI3P in phagocytosis. Treatment of cells with PI 3-kinase inhibitors impaired GST-2×FYVE-phagosome association supporting the authenticity of the biosensor staining. However, treatment with PI 3-kinase inhibitors did not inhibit E. histolytica-particle interaction, indicating that PI3P is not required for the initial step, but is required for subsequent steps of phagocytosis.