title: Ca2+-activated transbilayer movement of plasma membrane phospholipids in Leishmania donovani during ionomycin or thapsigargin stimulation.
abstract: The protozoan parasite Leishmania causes serious infections in humans all over the world. After being inoculated into the skin through the bite of an infected sandfly, Leishmania promastigotes must gain entry into macrophages to initiate a successful infection. Specific, surface exposed phospholipids have been implicated in Leishmania-macrophage interaction but the mechanisms controlling and regulating the plasma membrane lipid distribution remains to be elucidated. Here, we provide evidence for Ca(2+)-induced phospholipid scrambling in the plasma membrane of Leishmania donovani. Stimulation of parasites with ionomycin increases intracellular Ca(2+) levels and triggers exposure of phosphatidylethanolamine at the cell surface. We found that increasing intracellular Ca(2+) levels with ionomycin or thapsigargin induces rapid transbilayer movement of NBD-labelled phospholipids in the parasite plasma membrane that is bidirectional, independent of cellular ATP and not specific to the polar lipid head group. The findings suggest the presence of a Ca(2+)-dependent lipid scramblase activity in Leishmania parasites. Our studies further show that lipid scrambling is not activated by rapid exposure of promastigotes to higher physiological temperature that increases intracellular Ca(2+) levels.
authors.affiliation: Humboldt-Universität zu Berlin, Faculty of Mathematics and Natural Science I, Institute of Biology, Berlin, Germany.
authors.forename: Adrien
authors.initials: A
authors.lastname: Weingärtner
authors.forename: Marcos Gonzaga
authors.initials: MG
authors.lastname: dos Santos
authors.forename: Björn
authors.initials: B
authors.lastname: Drobot
authors.forename: Thomas Günther
authors.initials: TG
authors.lastname: Pomorski
mesh_terms: D017304:Annexin A5 / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism*; D005434:Flow Cytometry; D005456:Fluorescent Dyes / Q000378:metabolism; D015759:Ionomycin / Q000494:pharmacology*; D007893:Leishmania donovani / Q000187:drug effects* / Q000378:metabolism / Q000472:pathogenicity; D008051:Lipid Bilayers / Q000378:metabolism; D050356:Lipid Metabolism; D018613:Microscopy, Confocal; D010714:Phosphatidylethanolamines / Q000378:metabolism*; D049294:Phospholipid Transfer Proteins / Q000378:metabolism; D019284:Thapsigargin / Q000494:pharmacology*
chemical_list: D017304:Annexin A5; D005456:Fluorescent Dyes; D008051:Lipid Bilayers; D010714:Phosphatidylethanolamines; D049294:Phospholipid Transfer Proteins; C483858:phosphatidylethanolamine; D015759:Ionomycin; D019284:Thapsigargin; D002118:Calcium