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Salvatore J. Turco - One of the best experts on this subject based on the ideXlab platform.

  • The Leishmania donovani Lipophosphoglycan excludes the vesicular protonATPase from phagosomes by impairing the recruitment of synaptotagmin V
    2016
    Co-Authors: Adrien F. Vinet, Mitsunori Fukuda, Salvatore J. Turco, Albert Descoteaux
    Abstract:

    We recently showed that the exocytosis regulator Synaptotagmin (Syt) V is recruited to the nascent phagosome and remains associated throughout the maturation process. In this study, we investigated the possibility that Syt V plays a role in regulating interactions between the phagosome and the endocytic organelles. Silencing of Syt V by RNA interference revealed that Syt V contributes to phagolysosome biogenesis by regulating the acquisition of cathepsin D and the vesicular proton-ATPase. In contrast, recruitment of cathepsin B, the early endosomal marker EEA1 and the lysosomal marker LAMP1 to phagosomes was normal in the absence of Syt V. As Leishmania donovani promastigotes inhibit phagosome maturation, we investigated their potential impact on the phagosomal association of Syt V. This inhibition of phagolysosome biogenesis is mediated by the virulence glycolipid Lipophosphoglycan, a polymer of the repeating Galb1,4Mana1-PO4 units attached to the promastigote surface via an unusual glycosylphosphatidylinositol anchor. Our results showed that insertion of Lipophosphoglycan into ganglioside GM1-containing microdomains excluded or caused dissociation of Syt V from phagosome membranes. As a consequence, L. donovani promatigotes established infection in a phagosome from which the vesicular proton-ATPase was excluded and which failed to acidify. Collectively, these results reveal a novel function for Syt V in phagolysosome biogenesis and provide novel insight into the mechanism of vesicular proton-ATPase recruitment to maturing phagosomes. We also provide novel findings into the mechanism of Leishmania pathogenesis, whereby targetin

  • Structural comparison of Lipophosphoglycan from Leishmania turanica and L. major, two species transmitted by Phlebotomus papatasi
    Parasitology international, 2014
    Co-Authors: Petr Volf, Salvatore J. Turco, Paula Monalisa Nogueira, Jitka Myskova, Rodrigo P. Soares
    Abstract:

    The Lipophosphoglycan (LPG) of Leishmania major has a major role in the attachment to Phlebotomus papatasi midgut. Here, we investigated the comparative structural features of LPG of L. turanica, another species transmitted by P. papatasi. The mAb WIC 79.3, specific for terminal Gal(β1,3) side-chains, strongly reacted with L. turanica LPG. In contrast, L. turanica LPG was not recognized by arabinose-specific mAb 3F12. In conclusion, LPGs from L. major and L. turanica are similar, with the latter being less arabinosylated than L. major's. The high galactose content in L. turanica LPG is consistent with its predicted recognition by P. papatasi lectin PpGalec.

  • the leishmania donovani Lipophosphoglycan excludes the vesicular proton atpase from phagosomes by impairing the recruitment of synaptotagmin v
    PLOS Pathogens, 2009
    Co-Authors: Adrien F. Vinet, Mitsunori Fukuda, Salvatore J. Turco, Albert Descoteaux
    Abstract:

    We recently showed that the exocytosis regulator Synaptotagmin (Syt) V is recruited to the nascent phagosome and remains associated throughout the maturation process. In this study, we investigated the possibility that Syt V plays a role in regulating interactions between the phagosome and the endocytic organelles. Silencing of Syt V by RNA interference revealed that Syt V contributes to phagolysosome biogenesis by regulating the acquisition of cathepsin D and the vesicular proton-ATPase. In contrast, recruitment of cathepsin B, the early endosomal marker EEA1 and the lysosomal marker LAMP1 to phagosomes was normal in the absence of Syt V. As Leishmania donovani promastigotes inhibit phagosome maturation, we investigated their potential impact on the phagosomal association of Syt V. This inhibition of phagolysosome biogenesis is mediated by the virulence glycolipid Lipophosphoglycan, a polymer of the repeating Galβ1,4Manα1-PO4 units attached to the promastigote surface via an unusual glycosylphosphatidylinositol anchor. Our results showed that insertion of Lipophosphoglycan into ganglioside GM1-containing microdomains excluded or caused dissociation of Syt V from phagosome membranes. As a consequence, L. donovani promatigotes established infection in a phagosome from which the vesicular proton-ATPase was excluded and which failed to acidify. Collectively, these results reveal a novel function for Syt V in phagolysosome biogenesis and provide novel insight into the mechanism of vesicular proton-ATPase recruitment to maturing phagosomes. We also provide novel findings into the mechanism of Leishmania pathogenesis, whereby targeting of Syt V is part of the strategy used by L. donovani promastigotes to prevent phagosome acidification.

  • The Leishmania donovani Lipophosphoglycan Excludes the Vesicular Proton-ATPase from Phagosomes by Impairing the Recruitment of Synaptotagmin V
    PLoS pathogens, 2009
    Co-Authors: Adrien F. Vinet, Mitsunori Fukuda, Salvatore J. Turco, Albert Descoteaux
    Abstract:

    We recently showed that the exocytosis regulator Synaptotagmin (Syt) V is recruited to the nascent phagosome and remains associated throughout the maturation process. In this study, we investigated the possibility that Syt V plays a role in regulating interactions between the phagosome and the endocytic organelles. Silencing of Syt V by RNA interference revealed that Syt V contributes to phagolysosome biogenesis by regulating the acquisition of cathepsin D and the vesicular proton-ATPase. In contrast, recruitment of cathepsin B, the early endosomal marker EEA1 and the lysosomal marker LAMP1 to phagosomes was normal in the absence of Syt V. As Leishmania donovani promastigotes inhibit phagosome maturation, we investigated their potential impact on the phagosomal association of Syt V. This inhibition of phagolysosome biogenesis is mediated by the virulence glycolipid Lipophosphoglycan, a polymer of the repeating Galbeta1,4Manalpha1-PO(4) units attached to the promastigote surface via an unusual glycosylphosphatidylinositol anchor. Our results showed that insertion of Lipophosphoglycan into ganglioside GM1-containing microdomains excluded or caused dissociation of Syt V from phagosome membranes. As a consequence, L. donovani promatigotes established infection in a phagosome from which the vesicular proton-ATPase was excluded and which failed to acidify. Collectively, these results reveal a novel function for Syt V in phagolysosome biogenesis and provide novel insight into the mechanism of vesicular proton-ATPase recruitment to maturing phagosomes. We also provide novel findings into the mechanism of Leishmania pathogenesis, whereby targeting of Syt V is part of the strategy used by L. donovani promastigotes to prevent phagosome acidification.

  • Quantitation of Leishmania Lipophosphoglycan repeat units by capillary electrophoresis.
    Biochimica et biophysica acta, 2005
    Co-Authors: Tamara Barron, Salvatore J. Turco
    Abstract:

    The glycosylphosphatidylinositol (GPI)-anchored Lipophosphoglycan (LPG) of Leishmania is the dominant cell surface glycoconjugate of these pathogenic parasites. LPG is structurally characterized by a series of phosphoglycan repeat units. Determining the number of repeat units per LPG molecule has proven difficult using current technologies, such as mass spectrometry. As an alternative method to quantitate the number of repeat units in LPG, a procedure based on capillary electrophoretic analysis of the proportion of mannose to 2,5-anhydromannose (derived from the nonacetylated glucosamine of the GPI anchor of LPG) was developed. The CE-based technique is sensitive and relatively rapid compared to GC-MS-based protocols. Its application was demonstrated in quantitating the number of LPG repeat units from several species of Leishmania as well as from two life-cycle stages of these organisms.

Albert Descoteaux - One of the best experts on this subject based on the ideXlab platform.

  • The host cell secretory pathway mediates the export of Leishmania virulence factors out of the parasitophorous vacuole
    PLoS Pathogens, 2019
    Co-Authors: Guillermo Arango Duque, Mitsunori Fukuda, Armando Jardim, Etienne Gagnon, Albert Descoteaux
    Abstract:

    To colonize phagocytes, Leishmania subverts microbicidal processes through components of its surface coat that include Lipophosphoglycan and the GP63 metalloprotease. How these virulence glycoconjugates are shed, exit the parasitophorous vacuole (PV), and traffic within host cells is poorly understood. Here, we show that Lipophosphoglycan and GP63 are released from the parasite surface following phagocytosis and redistribute to the endoplasmic reticulum (ER) of macrophages. Pharmacological disruption of the trafficking between the ER and the Golgi hindered the exit of these molecules from the PV and dampened the cleavage of host proteins by GP63. Silencing by RNA interference of the soluble N-ethylmaleimide-sensitive-factor attachment protein receptors Sec22b and syntaxin-5, which regulate ER-Golgi trafficking, identified these host proteins as components of the machinery that mediates the spreading of Leishmania effectors within host cells. Our findings unveil a mechanism whereby a vacuolar pathogen takes advantage of the host cell's secretory pathway to promote egress of virulence factors beyond the PV.

  • Leishmania donovani Induces Autophagy in Human Blood–Derived Neutrophils
    Journal of Immunology, 2019
    Co-Authors: Durgesh Manohar Pitale, Albert Descoteaux, Neelaram Sahadev Gendalur, Chandrima Shaha
    Abstract:

    Neutrophils, the essential components of the innate immune system, are recruited in large numbers to the pathogen site of entry. Several pathogens induce neutrophil autophagy; however, function of autophagic events during Leishmania parasite infection remain unknown. In this article, we report a finding that is new, to our knowledge, of how Leishmania-induced human polymorphonuclear neutrophil (hPMN) autophagy regulates the silent mode of parasite transfer to macrophages by influencing the engulfment of infected cells. Leishmania infection induced a time-dependent autophagy increase responsive to block by 3-methyladenine but sensitive to ULK1/2 inhibition only after 3 h. This suggested the prevalence of canonical autophagy during later hours, ULK1/2 inhibition being able to block only canonical autophagy. Interaction of Rubicon and Beclin-1 at 1 h postinfection affirmed the prevalence of noncanonical autophagy during early infection. There was a reduction in macrophage uptake of parasite-exposed hPMNs treated with 3-methyladenine or ULK1/2 inhibitor, suggesting the involvement of both noncanonical and canonical autophagy in neutrophil engulfment. Autophagy inducer rapamycin augmented neutrophil engulfment by macrophages. Redistribution of hPMN surface CD47 encouraged neutrophil uptake. Activation of ERK, phosphoinositide 3-kinase, and NADPH oxidase-mediated reactive oxygen species generation were induced after parasite binding. The lpg1-knockout parasites expressing defective Lipophosphoglycan did not induce autophagy, indicating that Lipophosphoglycan is necessary for interaction with the neutrophils. Autophagy induction was TLR2/4 independent because the receptor blockade did not interfere with infection-induced autophagy. In summary, the engulfment of neutrophils by the macrophages was influenced by the escalation of hPMN autophagy, which is an important event during Leishmania infection.

  • The Leishmania donovani Lipophosphoglycan excludes the vesicular protonATPase from phagosomes by impairing the recruitment of synaptotagmin V
    2016
    Co-Authors: Adrien F. Vinet, Mitsunori Fukuda, Salvatore J. Turco, Albert Descoteaux
    Abstract:

    We recently showed that the exocytosis regulator Synaptotagmin (Syt) V is recruited to the nascent phagosome and remains associated throughout the maturation process. In this study, we investigated the possibility that Syt V plays a role in regulating interactions between the phagosome and the endocytic organelles. Silencing of Syt V by RNA interference revealed that Syt V contributes to phagolysosome biogenesis by regulating the acquisition of cathepsin D and the vesicular proton-ATPase. In contrast, recruitment of cathepsin B, the early endosomal marker EEA1 and the lysosomal marker LAMP1 to phagosomes was normal in the absence of Syt V. As Leishmania donovani promastigotes inhibit phagosome maturation, we investigated their potential impact on the phagosomal association of Syt V. This inhibition of phagolysosome biogenesis is mediated by the virulence glycolipid Lipophosphoglycan, a polymer of the repeating Galb1,4Mana1-PO4 units attached to the promastigote surface via an unusual glycosylphosphatidylinositol anchor. Our results showed that insertion of Lipophosphoglycan into ganglioside GM1-containing microdomains excluded or caused dissociation of Syt V from phagosome membranes. As a consequence, L. donovani promatigotes established infection in a phagosome from which the vesicular proton-ATPase was excluded and which failed to acidify. Collectively, these results reveal a novel function for Syt V in phagolysosome biogenesis and provide novel insight into the mechanism of vesicular proton-ATPase recruitment to maturing phagosomes. We also provide novel findings into the mechanism of Leishmania pathogenesis, whereby targetin

  • N.B.: When citing this work, cite the original article. Original Publication:
    2014
    Co-Authors: Åsa Holm, Adrien F. Vinet, Birgitta Rasmusson, Maria Lerm, Eva Särndahl, Karl-eric Magnusson, Albert Descoteaux, Martin Winberg Tinnerfelt
    Abstract:

    Leishmania donovani Lipophosphoglycan inhibits phagosomal maturation via action on membrane raft

  • Leishmania promastigotes: building a safe niche within macrophages.
    Frontiers in Cellular and Infection Microbiology, 2012
    Co-Authors: Neda Morandini, Albert Descoteaux
    Abstract:

    Upon their internalization by macrophages, Leishmania promastigotes inhibit phagolysosome biogenesis. The main factor responsible for this inhibition is the promastigote surface glycolipid Lipophosphoglycan (LPG). This glycolipid has a profound impact on the phagosome, causing periphagosomal accumulation of F-actin and disruption of phagosomal lipid microdomains. Functionally, this LPG-mediated inhibition of phagosome maturation is characterized by an impaired assembly of the NADPH oxidase and the exclusion of the vesicular proton-ATPase from phagosomes. In this chapter, we review the current knowledge concerning the nature of the intra-macrophage compartment in which Leishmania donovani promastigotes establish infection. We also describe how LPG enables this parasite to remodel the parasitophorous vacuole.

Michael A. J. Ferguson - One of the best experts on this subject based on the ideXlab platform.

  • Depletion of UDP-Glucose and UDP-Galactose Using a Degron System Leads to Growth Cessation of Leishmania major.
    Public Library of Science (PLoS), 2015
    Co-Authors: Sebastian Damerow, Michael A. J. Ferguson, Carolin Hoppe, Giulia Bandini, Patricia Zarnovican, Falk F R Buettner, Carsten G K Lüder, Françoise H Routier
    Abstract:

    Interconversion of UDP-glucose (UDP-Glc) and UDP-galactose (UDP-Gal) by the UDP-Glc 4´-epimerase intimately connects the biosynthesis of these two nucleotide sugars. Their de novo biosynthesis involves transformation of glucose-6-phosphate into glucose-1-phosphate by the phosphoglucomutase and subsequent activation into UDP-Glc by the specific UDP-Glc pyrophosphorylase (UGP). Besides UGP, Leishmania parasites express an uncommon UDP-sugar pyrophosphorylase (USP) able to activate both galactose-1-phosphate and glucose-1-phosphate in vitro. Targeted gene deletion of UGP alone was previously shown to principally affect expression of Lipophosphoglycan, resulting in a reduced virulence. Since our attempts to delete both UGP and USP failed, deletion of UGP was combined with conditional destabilisation of USP to control the biosynthesis of UDP-Glc and UDP-Gal. Stabilisation of the enzyme produced by a single USP allele was sufficient to maintain the steady-state pools of these two nucleotide sugars and preserve almost normal glycoinositolphospholipids galactosylation, but at the apparent expense of Lipophosphoglycan biosynthesis. However, under destabilising conditions, the absence of both UGP and USP resulted in depletion of UDP-Glc and UDP-Gal and led to growth cessation and cell death, suggesting that either or both of these metabolites is/are essential

  • Synthetic Fragments of Antigenic Lipophosphoglycans from Leishmania major and Leishmania mexicana and Their Use for Characterisation of the Leishmania Elongating α‐D‐Mannopyranosylphosphate Transferase
    Chemistry (Weinheim an der Bergstrasse Germany), 2005
    Co-Authors: Adrian P. Higson, Michael A. J. Ferguson, Andrew J. Ross, Françoise H Routier, Yury E Tsvetkov, Olga V. Sizova, Andrei V. Nikolaev
    Abstract:

    The phosphorylated branched heptasaccharides 7 and 8, the octasaccharide 9 and the phosphorylated trisaccharides 5 and 6, which are fragments of the phosphoglycan portion of the surface Lipophosphoglycans from Leishmania mexicana (5) or L. major (6-9), were synthesised by using the glycosyl hydrogenphosphonate method for the preparation of phosphodiester bridges. The compounds were tested as acceptor substrates/putative inhibitors for the Leishmania elongating alpha-D-mannosylphosphate transferase.

  • synthesis of oligomeric phosphono analogues of leishmania Lipophosphoglycan fragments
    Tetrahedron Letters, 2002
    Co-Authors: Vladimir S Borodkin, Michael A. J. Ferguson, Fiona C Milne, Andrei V. Nikolaev
    Abstract:

    A set of isosteric phosphono (C-glycoside) analogues of Leishmania Lipophosphoglycan fragments have been synthesised by making use of a sequence of uniformly stereoselective glycosylation reactions of phosphono-oligosaccharide glycosyl acceptors with phosphono-oligosaccharide thioglycosides.

  • The preparation of neoglycoconjugates containing inter-saccharide phosphodiester linkages as potential anti-Leishmania vaccines
    Glycoconjugate Journal, 1999
    Co-Authors: Françoise H Routier, Andrei V. Nikolaev, Michael A. J. Ferguson
    Abstract:

    The Leishmania express complex glycoconjugates containing phosphosaccharide repeat units at all stages of their life-cycle. One of these molecules, Lipophosphoglycan (LPG) has been suggested to be a vaccine candidate. To assess the immunological properties of Leishmania phosphosaccharides, we have prepared neoglycoproteins and neoglycolipids containing synthetic Leishmania phosphosaccharide repeats. The coupling procedure uses the dec-9-enyl spacer of previously synthesised phosphosaccharides for linkage to protein and phospholipid. This alkene moiety is converted by ozonolysis to an aldehyde which is then attached to protein and phospholipid amino groups by reductive amination. The procedure produces neoglycoconjugates in good yield and without compromising the labile phosphodiester linkages within the phosphosaccharide chains.

  • Typing of Leishmania Lipophosphoglycans by electrospray mass spectrometry.
    Molecular and biochemical parasitology, 1999
    Co-Authors: Iain B. H. Wilson, Niall O’donnell, Simon Allen, Angela Mehlert, Michael A. J. Ferguson
    Abstract:

    A method has been developed to identify the repeating phosphosaccharide units of Leishmania Lipophosphoglycans using electrospray mass-spectrometry (ES-MS). Cone voltage-induced fragmentation of intact Lipophosphoglycan was found to be as effective as analysis of mild acid hydrolysates in identifying the degree of modification of the repeating units of Lipophosphoglycans derived from Leishmania mexicana and Leishmania major. This finding was exploited in a 'rapid-analysis' method in which a crude organic extract of approximately 2 x 10(9) L. major promastigote cells was loaded onto a reverse-phase cartridge for immediate elution into the mass-spectrometer. Using this approach, it was possible to identify the repeating units by total ion scanning and scanning for parents of the m/z 79 (PO3-) fragment ion. This approach is suitable for quick-typing of Lipophosphoglycan repeats and was shown to detect alterations in repeat side chains caused by: (1) culturing L. major promastigotes in the presence of L-fucose; and (2) in vitro metacyclogenesis of L. major promastigotes. It is anticipated that the method will be applicable to small samples of cultured field isolates or genetically-manipulated strains.

Andrei V. Nikolaev - One of the best experts on this subject based on the ideXlab platform.

Thomas Ilg - One of the best experts on this subject based on the ideXlab platform.

  • Lipophosphoglycan of the protozoan parasite Leishmania: stage- and species-specific importance for colonization of the sandfly vector, transmission and virulence to mammals
    Medical Microbiology and Immunology, 2001
    Co-Authors: Thomas Ilg
    Abstract:

    Leishmaniasis is a major health problem to the human population of the tropics, subtropics and Mediterranean regions. This disease is caused by the parasitic protozoa Leishmania , which have adapted to survive in several hostile environments such as the vector insect midgut, blood and the mammalian macrophage phagolysosome. Several Leishmania glycoconjugates have been implicated as key molecules for these remarkable capabilities. This review summarizes the current knowledge on potential and proven functions of the most prominent of the Leishmania glycoconjugates, the Lipophosphoglycan.

  • Monoclonal antibodies directed against Leishmania secreted acid phosphatase and Lipophosphoglycan. Partial characterization of private and public epitopes.
    European journal of biochemistry, 1993
    Co-Authors: Thomas Ilg, Dorothee Harbecke, Martin Wiese, Peter Overath
    Abstract:

    Leishmania promastigotes, the stage of the parasite characteristic for the sandfly vector, express an abundant glycoconjugate, called Lipophosphoglycan, at their surface. Lipophosphoglycan consists of lysoalkyl-sn-glycerophosphoinositol linked to a phosphosaccharide core conserved in all species, which is connected to PO4-6Gal beta 1,4Man alpha 1 repeats with species-specific substitutions at the Gal residue; the repeats are capped by conserved and species-specific oligosaccharides. Most Leishmania species also secrete an acid phosphatase, which, in Leishmania mexicana, is a filamentous complex composed of a phosphorylated glycoprotein and non-covalently associated proteo-(high-molecular-mass)phosphoglycan. The secreted acid phosphatase complex was used as an antigen to derive a panel of monoclonal antibodies (mAbs). A total of 25 mAbs (17 novel and 8 previously described) were tested by different techniques for their specificity against Lipophosphoglycan and secreted acid phosphatase from several Leishmania species. This comparison and the modification of the antigens by chemical or enzymic treatments allowed a classification of the mAbs into several groups. First, from 25 mAbs examined, 22 recognize Lipophosphoglycan and the enzyme complex of L. mexicana; only three are specific for secreted acid phosphatase. Two of the latter group are also directed against carbohydrate structures, whereas the third mAb recognizes the 100-kDa polypeptide of the complex. The secreted acid-phosphatase-specific class detects antigen in the flagellar pocket of promastigotes while all anti-Lipophosphoglycan mAbs bind to the cell surface. Second, all 15 anti-Lipophosphoglycan mAbs investigated in detail appear to be directed against the phosphosaccharide repeats or the cap structure rather than the phosphosaccharide core. Two mAbs recognize terminal cap-structures containing Man alpha 1,2Man residues. Four antibodies are specific for L. mexicana and are probably directed against PO4-6[Glc beta 1,3]Gal beta 1,4Man alpha 1 repeats while six mAbs react with the unmodified repeats. Two antibodies specific for Leishmania major recognize Gal beta 1,3-substituted repeats unique for Lipophosphoglycan from this species. Analysis by immunoblotting indicates that the high-molecular-mass proteo-phosphoglycan of L. mexicana secreted acid phosphatase carries epitopes for all anti-Lipophosphoglycan mAbs suggesting the presence of capped phosphosaccharide repeats while the enzymically active glycoprotein subunit is modified by caps but probably not by repeats. In the case of Leishmania donovani secreted acid phosphatase, the enzymically active polypeptide may be directly modified by repeats. The mAbs are used to characterize changes in Lipophosphoglycan structure, which occur in culture during the transition of promastigotes from the logarithmic to the stationary growth phase.(ABSTRACT TRUNCATED AT 400 WORDS)