Proteophosphoglycans of Leishmania mexicana: Identification, purification, structural and ultrastructural characterization of the secreted promastigote proteophosphoglycan pPPG2, a stage-specific glycoisoform of amastigote aPPG

Klein, Christian; Göpfert, Ulrich; Goehring, Nathan W.; Stierhof, York‐Dieter; Ilg, Thomas

doi:10.1042/bj3440775

Cited by 12 publications

(9 citation statements)

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“…There are several possible explanations for the evident surface binding, but limited detection, of internal H2A in amastigotes. First, it is known that amastigotes resemble the lpg1 Ϫ promastigotes in that they lack LPG1 but retain PPG (18) and that the structure of the glycans found on amastigote PPG in L. mexicana differs considerably from the simpler LPG-like linear PG polymers found on promastigote PPG (17,21). These unique structures may allow interaction with histones but limit their translocation.…”

Section: Discussionmentioning

confidence: 99%

Differential Microbicidal Effects of Human Histone Proteins H2A and H2B on Leishmania Promastigotes and Amastigotes

Wang

Chen

Luo³

et al. 2011

Infect Immun

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Recent studies have shown that histone proteins can act as antimicrobial peptides in host defense against extracellular bacteria, fungi, and Leishmania promastigotes. In this study, we used human recombinant histone proteins to further study their leishmaniacidal effects and the underlying mechanisms. We found that the histones H2A and H2B (but not H1(0)) could directly and efficiently kill promastigotes of Leishmania amazonensis, L. major, L. braziliensis, and L. mexicana in a treatment dose-dependent manner. Scanning electron microscopy revealed surface disruption of histone-treated promastigotes. More importantly, the preexposure of promastigotes to histone proteins markedly decreased the infectivity of promastigotes to murine macrophages (Mφs) in vitro. However, axenic and lesion-derived amastigotes of L. amazonensis and L. mexicana were relatively resistant to histone treatment, which correlated with the low levels of intracellular H2A in treated amastigotes. To understand the mechanisms underlying these differential responses, we investigated the role of promastigote surface molecules in histone-mediated killing. Compared with the corresponding controls, transgenic L. amazonensis promastigotes expressing lower levels of surface gp63 proteins were more susceptible to histone H2A, while L. major and L. mexicana promastigotes with targeted deletion of the lipophosphoglycan 2 (lpg2) gene (but not the lpg1 gene) were more resistant to histone H2A. We discuss the influence of promastigote major surface molecules in the leishmaniacidal effect of histone proteins. This study provides new information on host innate immunity to different developmental stages of Leishmania parasites.

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Section: Discussionmentioning

confidence: 99%

Differential Microbicidal Effects of Human Histone Proteins H2A and H2B on Leishmania Promastigotes and Amastigotes

Wang

Chen

Luo³

et al. 2011

Infect Immun

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“…1995, 1996, 1999 a ; Gopfert et al 1999; Klein et al . 1999; Ilg, 2000). No such characterization of PPG has been reported in the case of L. donovani .…”

Section: Introductionmentioning

confidence: 99%

“…Since LPG seems to be absent from L. donovani amastigotes, PPG may play the important functions attributed to LPG in attachment of the parasites to host macrophages (Ilgoutz and McConville, 2001). PPG is a product of both promastigotes (pPPG) and amastigotes (aPPG) as observed in the case of L. mexicana and L. major, the causative organisms for cutaneous leishmaniasis (CL), and has been demonstrated to have species and stage-specific functions (Ilg et al 1995(Ilg et al , 1996Gopfert et al 1999 ;Klein et al 1999 ;Ilg, 2000). No such characterization of PPG has been reported in the case of L. donovani.…”

Section: Introductionmentioning

confidence: 99%

Proteophosphoglycan is differentially expressed in sodium stibogluconate-sensitive and resistant Indian clinical isolates ofLeishmania donovani

et al. 2007

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Leishmania produce several types of mucin-like glycoproteins called proteophosphoglycans (PPGs) some of which are secreted while others are found on the surface of promastigotes and amastigotes. These proteins are thought to be important in the transmission, invasion and subsequent intracellular survival of parasites. The structure and function of PPGs are species and stage-specific in the case of L. major and L. mexicana, but no such information has hitherto been available for L. donovani. This study presents, for the first time, an initial characterization (localization) of PPG in sodium stibogluconate (SSG)-resistant and sensitive clinical isolates of L. donovani from Bihar (India) by confocal microscopy, flow cytometry and Western blotting using antibodies to L. major PPG. Confocal microscopy analysis revealed that both promastigotes and amastigotes possess PPG on their cell membrane and flagellar pocket membrane but its expression was variable in different isolates. The quantitative analysis by FACS and Western blotting showed that the expression and intensity of PPG bands was higher in SSG-resistant isolates. This study suggests the possibilities of involvement of PPG in drug-resistant mechanisms and of using PPG abundance as a marker for identifying drug-resistant clinical isolates in Indian kala azar.

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“…The rationale driving this research has been that these protozoan parasites are likely dependent on secretion of effector molecules into the host extra- and intracellular environments for initiation and maintenance of successful infection. This theory is based on investigations of individual secreted proteins (Vannier-Santos et al, 1995 ; Hubel et al, 1997 ; Klein et al, 1999 ; Joshi et al, 2002 ; Lieke et al, 2008 ; Gomez et al, 2009 ; Halle et al, 2009 ; Silverman et al, 2010b ; Jaramillo et al, 2011 ) and proteins mechanistically involved in the secretion pathway (Besteiro et al, 2006 ), which showed reduced virulence after loss of protein function or secretion. It has been known for some time that these eukaryotic organisms use a classical secretion pathway for the proper dissemination of newly translated proteins throughout the cell and it has been thought that this pathway was the route to the cell surface (McConville et al, 2002 ).…”

Section: Introductionmentioning

confidence: 99%

Leishmania Exosomes Deliver Preemptive Strikes to Create an Environment Permissive for Early Infection

Silverman¹,

Reiner²

2012

Front. Cell. Inf. Microbio.

108

113

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Herein, we review evidence supporting a role for Leishmania exosomes during early infection. We suggest a model in which Leishmania secreted microvesicles released into the extracellular milieu deliver effector cargo to host target cells. This cargo mediates immunosuppression and functionally primes host cells for Leishmania invasion. Leishmania ssp. release microvesicles and the amount of vesicle release and the specific protein cargo of the vesicles is sensitive to changes in environmental conditions that mimic infection. Leishmania exosomes influence the phenotype of treated immune cells. For example, wild-type (WT) exosomes attenuate interferon-γ-induced pro-inflammatory cytokine production (TNF-α) by Leishmania-infected monocytes while conversely enhancing production of the anti-inflammatory cytokine IL-10. The Leishmania proteins GP63 and elongation factor-1α (EF-1α) are found in secreted vesicles and are likely important effectors responsible for these changes in phenotype. GP63 and EF-1α access host cell cytosol and activate multiple host protein-tyrosine phosphatases (PTPs). Activation of these PTPs negatively regulates interferon-γ signaling and this prevents effective expression of the macrophage microbicidal arsenal, including TNF-α and nitric oxide. In addition to changing macrophage phenotype, WT vesicles dampen the immune response of monocyte-derived dendritic cells and CD4+ T lymphocytes. This capacity is lost when the protein cargo of the vesicles is modified, specifically when the amount of GP63 and EF-1α in the vesicles is reduced. It appears that exosome delivery of effector proteins results in activation of host PTPs and the negative regulatory effects of the latter creates a pro-parasitic environment. The data suggest that Leishmania exosomes secreted upon initial infection are capable of delivering effector cargo to naïve target cells wherein the cargo primes host cells for infection by interfering with host cell signaling pathways.

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Proteophosphoglycans of Leishmania mexicana: Identification, purification, structural and ultrastructural characterization of the secreted promastigote proteophosphoglycan pPPG2, a stage-specific glycoisoform of amastigote aPPG

Cited by 12 publications

References 50 publications

Differential Microbicidal Effects of Human Histone Proteins H2A and H2B on Leishmania Promastigotes and Amastigotes

Differential Microbicidal Effects of Human Histone Proteins H2A and H2B on Leishmania Promastigotes and Amastigotes

Proteophosphoglycan is differentially expressed in sodium stibogluconate-sensitive and resistant Indian clinical isolates ofLeishmania donovani

Leishmania Exosomes Deliver Preemptive Strikes to Create an Environment Permissive for Early Infection

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