title: Leishmania major : detection of membrane-bound protein tyrosine phosphatase.
abstract: PTPases have been reported as a virulence factor in different pathogens. Recent studies suggest that PTPases play a role in the pathogenesis of Leishmania infections through activation of macrophage PTPases by the parasite. We report here the presence of a membrane-bound PTPase in Leishmania major promastigotes. We detected differences in the PTPases present in the procyclic and metacyclic stages of promastigotes. In metacyclic promastigotes, the PTPase activity was totally inhibited by specific PTPase and serine/threonine inhibitors, whereas in procyclic promastigotes the PTPase activity was inhibited only with PTPase inhibitors. Two antibodies against the catalytic domains of the human placental PTPase1B and a PTPase from Trypanosoma brucei cross-reacted with a 55-60 kDa molecule present in the soluble detergent-extracted fraction of a Leishmania homogenate. Metacyclic promastigotes expressed more of this molecule than parasites in the procyclic stage. Yet the specific activity of the enzyme was lower in metacyclic than in procyclic promastigotes. Ultrastructural localization of the enzyme showed that it was more membrane-associated in metacyclic promastigotes, whereas in procyclic promastigotes it was scattered throughout the cytoplasm. This is the first demonstration of a PTPase present in Leishmania major promastigotes that differs in expression, activity and ultrastructural localization between the procyclic and metacyclic stages of the parasite's life-cycle.
authors.affiliation: Departamento de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, México, D.F., México. maguirre@servidor.unam.mx
authors.forename: M M
authors.initials: MM
authors.lastname: Aguirre-García
authors.forename: A R
authors.initials: AR
authors.lastname: Escalona-Montaño
authors.forename: N
authors.initials: N
authors.lastname: Bakalara
authors.forename: A
authors.initials: A
authors.lastname: Pérez-Torres
authors.forename: L
authors.initials: L
authors.lastname: Gutiérrez-Kobeh
authors.forename: I
authors.initials: I
authors.lastname: Becker
mesh_terms: D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D015153:Blotting, Western / Q000379:methods; D002458:Cell Fractionation; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018320:Leishmania major / Q000201:enzymology* / Q000472:pathogenicity* / Q000648:ultrastructure; D008018:Life Cycle Stages / Q000502:physiology; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism; D046529:Microscopy, Electron, Transmission / Q000379:methods; D017830:Octoxynol / Q000737:chemistry; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism; D015800:Protozoan Proteins / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D037521:Virulence Factors / Q000037:antagonists & inhibitors / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D015800:Protozoan Proteins; D037521:Virulence Factors; D017830:Octoxynol; D000135:Acid Phosphatase; D017027:Protein Tyrosine Phosphatases