Expression of lipophosphoglycan, high-molecular weight phosphoglycan and glycoprotein 63 in promastigotes and amastigotes of Leishmania mexicana

Bahr, Valerie; Stierhof, York‐Dieter; Ilg, Thomas; Demar, Monika; Quinten, Margret; Overath, Peter

doi:10.1016/0166-6851(93)90095-f

Cited by 121 publications

(99 citation statements)

References 31 publications

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“…Growth-dependent changes in GPI biosynthesis are also likely to account for the dramatic change in surface architecture of these parasites after promastigotes differentiate to amastigotes in the phagolysosome compartment of mammalian macrophages. Amastigotes lack the surface coat of GPI-anchored glycoproteins and LPG, but retain a densely packed surface layer of free GPIs that appear to be the major surface components (McConville and Blackwell, 1991;Bahr et al, 1993;Winter et al, 1994).…”

Section: Introductionmentioning

confidence: 99%

Regulated Degradation of an Endoplasmic Reticulum Membrane Protein in a Tubular Lysosome inLeishmania mexicana

Mullin¹,

Foth

Ilgoutz³

et al. 2001

MBoC

163

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The cell surface of the human parasite Leishmania mexicana is coated with glycosylphosphatidylinositol (GPI)-anchored macromolecules and free GPI glycolipids. We have investigated the intracellular trafficking of green fluorescent protein-and hemagglutinin-tagged forms of dolicholphosphate-mannose synthase (DPMS), a key enzyme in GPI biosynthesis in L. mexicana promastigotes. These functionally active chimeras are found in the same subcompartment of the endoplasmic reticulum (ER) as endogenous DPMS but are degraded as logarithmically growing promastigotes reach stationary phase, coincident with the down-regulation of endogenous DPMS activity and GPI biosynthesis in these cells. We provide evidence that these chimeras are constitutively transported to and degraded in a novel multivesicular tubule (MVT) lysosome. This organelle is a terminal lysosome, which is labeled with the endocytic marker FM 4-64, contains lysosomal cysteine and serine proteases and is disrupted by lysomorphotropic agents. Electron microscopy and subcellular fractionation studies suggest that the DPMS chimeras are transported from the ER to the lumen of the MVT via the Golgi apparatus and a population of 200-nm multivesicular bodies. In contrast, soluble ER proteins are not detectably transported to the MVT lysosome in either log or stationary phase promastigotes. Finally, the increased degradation of the DPMS chimeras in stationary phase promastigotes coincides with an increase in the lytic capacity of the MVT lysosome and changes in the morphology of this organelle. We conclude that lysosomal degradation of DPMS may be important in regulating the cellular levels of this enzyme and the stage-dependent biosynthesis of the major surface glycolipids of these parasites.

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Section: Introductionmentioning

confidence: 99%

Regulated Degradation of an Endoplasmic Reticulum Membrane Protein in a Tubular Lysosome inLeishmania mexicana

Mullin¹,

Foth

Ilgoutz³

et al. 2001

MBoC

163

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“…However, the fact that these proteins are encoded by multicopy polymorphic genes (Button et al, 1989;Lohman et al, 1990;Symons et al, 1994) has hindered elucidation of their function by genetic analysis (Joshi et al, 1998). Moreover, surface expression of gp63 and PSA2 is dramatically down-regulated in the amastigote stage of some Leishmania species and variable within particular parasite populations of others (Bahr et al, 1993;Handman et al, 1995) such that the precise function of these parasite proteins in the mammalian host remains unclear.Proteins that are destined to receive a GPI anchor are synthesized as precursor proteins with an N-terminal signal sequence that targets the protein to the endoplasmic reticulum (ER) and a C-terminal GPI attachment signal. The latter § Corresponding author.…”

mentioning

confidence: 99%

Leishmania mexicanaMutants Lacking Glycosylphosphatidylinositol (GPI):Protein Transamidase Provide Insights into the Biosynthesis and Functions of GPI-anchored Proteins

Hilley

Zawadzki

McConville

et al. 2000

MBoC

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The major surface proteins of the parasitic protozoon Leishmania mexicana are anchored to the plasma membrane by glycosylphosphatidylinositol (GPI) anchors. We have cloned the L. mexicana GPI8 gene that encodes the catalytic component of the GPI:protein transamidase complex that adds GPI anchors to nascent cell surface proteins in the endoplasmic reticulum. Mutants lacking GPI8 (⌬GPI8) do not express detectable levels of GPI-anchored proteins and accumulate two putative protein-anchor precursors. However, the synthesis and cellular levels of other nonprotein-linked GPIs, including lipophosphoglycan and a major class of free GPIs, are not affected in the ⌬GPI8 mutant. Significantly, the ⌬GPI8 mutant displays normal growth in liquid culture, is capable of differentiating into replicating amastigotes within macrophages in vitro, and is infective to mice. These data suggest that GPI-anchored surface proteins are not essential to L. mexicana for its entry into and survival within mammalian host cells in vitro or in vivo and provide further support for the notion that free GPIs are essential for parasite growth. INTRODUCTIONLeishmania are protozoan parasites that cause a spectrum of diseases in humans. These parasites alternate between a flagellated promastigote stage that proliferates within the midgut of the sandfly vector and a nonmotile amastigote stage that invades mammalian macrophages, where they occupy the phagolysosome compartment. The cell surface of the promastigote stage is coated by a protective glycocalyx that comprises a number of glycosylphosphatidylinositol (GPI)-anchored glycoproteins, a complex GPI-anchored lipophosphoglycan (LPG), and a family of free GPIs (termed glycoinositolphospholipids [GIPLs]) Beverley and Turco, 1998; Figure 1). Components in this glycoclayx are thought to be essential for parasite survival and infectivity in the diverse host Beverley and Turco, 1998). The GPIanchored glycoproteins include an abundant metalloproteinase, termed gp63 or leishmanolysin, and the promastigote surface antigen (PSA2)/gp46 family of glycoproteins Murray et al., 1989;Frommel et al., 1990;Lohman et al., 1990). Gp63 has been shown to be proteolytically active against a wide variety of different peptide substrates and has been reported to act as a ligand for macrophage receptors, either directly or after opsonization with complement, to protect the parasites from complementmediated lysis and also to contribute to the pathology of lesion development (see Alexander and Russell, 1992;Joshi et al., 1998). However, the fact that these proteins are encoded by multicopy polymorphic genes (Button et al., 1989;Lohman et al., 1990;Symons et al., 1994) has hindered elucidation of their function by genetic analysis (Joshi et al., 1998). Moreover, surface expression of gp63 and PSA2 is dramatically down-regulated in the amastigote stage of some Leishmania species and variable within particular parasite populations of others (Bahr et al., 1993;Handman et al., 1995) such that the precise function of these parasite pro...

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“…LPG also induces the accumulation of periphagosomal F-actin, which may form a physical barrier that potentially prevents vesicular trafficking to the phagosome [46]. The role of LPG in the parasite survival is however restricted to the promastigote stage as this molecule is highly down-modulated in amastigotes [47]. Another pathogenicity factor, the cysteine proteinase B (CPB), contributes to L. mexicana virulence as knock-out parasite induced a protective Th1 response and poor lesion growth in BALB/c mice [48].…”

Section: -Parasitophorous Vacuole Formationmentioning

confidence: 99%

Leishmania, the phagosome, and host responses: The journey of a parasite

Séguin¹,

Descoteaux²

2016

Cellular Immunology

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Expression of lipophosphoglycan, high-molecular weight phosphoglycan and glycoprotein 63 in promastigotes and amastigotes of Leishmania mexicana

Cited by 121 publications

References 31 publications

Regulated Degradation of an Endoplasmic Reticulum Membrane Protein in a Tubular Lysosome inLeishmania mexicana

Regulated Degradation of an Endoplasmic Reticulum Membrane Protein in a Tubular Lysosome inLeishmania mexicana

Leishmania mexicanaMutants Lacking Glycosylphosphatidylinositol (GPI):Protein Transamidase Provide Insights into the Biosynthesis and Functions of GPI-anchored Proteins

Leishmania, the phagosome, and host responses: The journey of a parasite

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