Roles of free GPIs in amastigotes of Leishmania.
Glycosylated phosphatidylinositols (GPIs) are abundant cell surface molecules of the Leishmania. Amastigote-specific GPIs AmGPI-Y and AmGPI-Z, both ethanolamine (EtN)-containing glycolipids, were identified in Leishmania amazonensis. A paucity of GPI-anchored proteins in amastigotes of L. amazonensis made the kinetoplastid suitable for evaluating the importance of free (i.e. unconjugated to protein or polysaccharide) GPIs. A strain deficient in both AmGPI-Y and AmGPI-Z was produced by stable transfection of wild-type Leishmania with a GPI-phospholipase C gene. Phosphatidylinositol deficiency was not detected in the transfectants. GPI-deficient promastigotes infected murine macrophages in vitro and differentiated into amastigotes whose growth was arrested within the host cells. Cytostasis of amastigotes was also observed during axenic culture of GPI-deficient parasites. In a hamster model of leishmaniasis, GPI-deficient promastigotes produced smaller lesions with 20-fold fewer amastigotes than infections with control parasites. Together, these observations indicate that EtN-GPIs may be essential for amastigote viability, replication, and/or virulence. Implicit in these observations is the notion that drugs targeted against the GPI biosynthetic pathway might be of value in the management of human leishmaniasis.
Mensa-Wilmot
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Department of Cellular Biology, University of Georgia, Athens 30602, USA. mensawil@cb.uga.edu
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D000818:Animals; D006224:Cricetinae; D006017:Glycolipids / Q000032:analysis / Q000302:isolation & purification; D017261:Glycosylphosphatidylinositols / Q000737:chemistry / Q000378:metabolism*; D007894:Leishmania mexicana / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism / Q000472:pathogenicity; D016773:Leishmaniasis, Cutaneous / Q000469:parasitology*; D008264:Macrophages / Q000469:parasitology*; D008647:Mesocricetus; D051379:Mice; D011134:Polysaccharides / Q000032:analysis; D014162:Transfection; D010738:Type C Phospholipases / Q000235:genetics / Q000378:metabolism; D014774:Virulence
D006017:Glycolipids; D017261:Glycosylphosphatidylinositols; D011134:Polysaccharides; D010738:Type C Phospholipases