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Published on: August 26, 2016
Mechanisms associated with Acanthamoeba castellanii (T4) phagocytosis
Selwa Alsam1, James Sissons, Ricky Dudley
1School of Biological and Chemical Sciences, Birkbeck, University of London, London WC1E 7HX, UK.
Abstract:
Using fluorescein isothiocyanate (FITC)-labelled Escherichia coli, phagocytosis in Acanthamoeba is studied. This assay is based on the quenching effect of trypan blue on FITC-labelled E. coli. Only intracellular E. coli retain their fluorescence, which are easily discriminated from non-fluorescent adherent bacteria. Acanthamoeba uptake of E. coli is significantly reduced in the presence of genistein, a protein tyrosine kinase inhibitor. In contrast, sodium orthovanadate (protein tyrosine phosphatase inhibitor) increases bacterial uptake by Acanthamoeba. Treatment of Acanthamoeba with cytochalasin D (actin polymerization inhibitor) abolished the ability of Acanthamoeba to phagocytose E. coli suggesting that tyrosine kinase-mediated signaling may play a role in Acanthamoeba phagocytosis. In addition, we showed that phosphatidylinositol 3-kinase (PI3K) plays an important role in Acanthamoeba uptake of E. coli. Role of mannose-binding protein in Acanthamoeba phagocytosis is discussed further.
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