title: Exclusion of synaptotagmin V at the phagocytic cup by Leishmania donovani lipophosphoglycan results in decreased promastigote internalization.
abstract: Regulators of membrane fusion play an important role in phagocytosis, as they regulate the focal delivery of endomembrane that is required for optimal internalization of large particles. During internalization of Leishmania promastigotes, the surface glycolipid lipophosphoglycan (LPG) is transferred to the macrophage membrane and modifies its fusogenic properties. In this study, we investigated the impact of LPG on the recruitment of the exocytosis regulator synaptotagmin V (Syt V) at the area of internalization and on the early steps of phagocytosis. Using Leishmania donovani LPG-defective mutants and LPG-coated particles, we established that LPG reduces the phagocytic capacity of macrophages and showed that it causes exclusion of Syt V from the nascent phagosome. Silencing of Syt V inhibited phagocytosis to the same extent as LPG, and these effects were not cumulative, consistent with a Syt V-dependent mechanism for the inhibition of phagocytosis by LPG. Previous work has revealed that LPG-mediated exclusion of Syt V from phagosomes prevents the recruitment of the vacuolar ATPase and acidification. Thus, whereas exclusion of Syt V from phagosomes in the process of formation may be beneficial for the creation of a hospitable intracellular niche, it reduces the phagocytic capacity of macrophages. We propose that the cost associated with a reduced internalization rate may be compensated by increased survival, and could lead to a greater overall parasite fitness.
authors.affiliation: INRS-Institut Armand-Frappier and Centre for Host-Parasite Interactions, Laval, QC H7V 1B7, Canada.
authors.forename: Adrien F
authors.initials: AF
authors.lastname: Vinet
authors.affiliation: INRS-Institut Armand-Frappier and Centre for Host-Parasite Interactions, Laval, QC H7V 1B7, Canada.
authors.forename: Silvana
authors.initials: S
authors.lastname: Jananji
authors.affiliation: Department of Biochemistry, University of Kentucky, Lexington, KY 40536, USA.
authors.forename: Salvatore J
authors.initials: SJ
authors.lastname: Turco
authors.affiliation: Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, Miyagi 980-8578, Japan.
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Fukuda
authors.affiliation: INRS-Institut Armand-Frappier and Centre for Host-Parasite Interactions, Laval, QC H7V 1B7, Canada.
authors.forename: Albert
authors.initials: A
authors.lastname: Descoteaux
mesh_terms: D000818:Animals; D002460:Cell Line; D005260:Female; D006028:Glycosphingolipids / Q000378:metabolism*; D007893:Leishmania donovani / Q000254:growth & development / Q000276:immunology / Q000502:physiology*; D008264:Macrophages / Q000276:immunology* / Q000469:parasitology; D051379:Mice; D008807:Mice, Inbred BALB C; D010587:Phagocytosis / Q000276:immunology*; D010588:Phagosomes / Q000276:immunology; D050857:Synaptotagmins / Q000378:metabolism*
chemical_list: D006028:Glycosphingolipids; C008290:lipophosphonoglycan; D050857:Synaptotagmins