title: Kinesin 5B is necessary for delivery of membrane and receptors during FcγR-mediated phagocytosis.
abstract: FcγR-mediated phagocytosis is a cellular event that is evolutionary conserved to digest IgG-opsonized pathogens. Pseudopod formation during phagocytosis is a limiting step in managing the uptake of particles, and in this paper, we show that the conventional kinesin is involved in both receptor and membrane delivery to the phagocytic cup. Expression of a mutant kinesin isoform (GFP dominant negative mutant of kinesin H chain [EGFP-Kif5B-DN]) in RAW264.7 cells significantly reduced binding of IgG-sheep RBCs when macrophages were faced with multiple encounters with opsonized particles. Scanning electron microscopy analysis of EGFP-Kif5B-DN-expressing cells challenged with two rounds of IgG-sheep RBCs showed sparse, extremely thin pseudopods. We saw disrupted Rab11 trafficking to the phagocytic cup in EGFP-Kif5B-DN-transfected cells. Our particle overload assays also implicated phagosome membrane recycling in pseudopod formation. We observed reduced phagosome fission and trafficking in mutant kinesin-expressing cells, as well as reduced cell surface expression of FcγRs and Mac-1 receptors. In conclusion, anterograde trafficking via kinesin is essential for both receptor recycling from the phagosome and delivery of Rab11-containing membrane stores to effect broad and functional pseudopods during FcγR-mediated phagocytosis.
authors.affiliation: Department of Biological Sciences, University of Toronto Scarborough, Toronto, Ontario, M1C 1A4 Canada.
authors.forename: Kristen E
authors.initials: KE
authors.lastname: Silver
authors.forename: Rene E
authors.initials: RE
authors.lastname: Harrison
mesh_terms: D000818:Animals; D002460:Cell Line; D016764:Cell Polarity / Q000235:genetics / Q000276:immunology; D015536:Down-Regulation / Q000235:genetics / Q000276:immunology; D005089:Exocytosis / Q000235:genetics / Q000276:immunology; D007425:Intracellular Membranes / Q000201:enzymology* / Q000276:immunology* / Q000648:ultrastructure; D016547:Kinesins / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D051379:Mice; D010587:Phagocytosis / Q000235:genetics / Q000276:immunology*; D010588:Phagosomes / Q000201:enzymology / Q000276:immunology / Q000648:ultrastructure; D011485:Protein Binding / Q000235:genetics / Q000276:immunology; D021381:Protein Transport / Q000235:genetics / Q000276:immunology; D011554:Pseudopodia / Q000201:enzymology / Q000276:immunology / Q000648:ultrastructure; D017452:Receptors, IgG / Q000378:metabolism* / Q000502:physiology / Q000648:ultrastructure; D050600:SNARE Proteins / Q000378:metabolism* / Q000648:ultrastructure; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D014162:Transfection; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D000099193:rab11 GTP-Binding Proteins
chemical_list: D016547:Kinesins; D017452:Receptors, IgG; D050600:SNARE Proteins; D020691:rab GTP-Binding Proteins; D000099193:rab11 GTP-Binding Proteins; C475469:Kif5b protein, mouse