title: Nitric oxide-mediated proteasome-dependent oligonucleosomal DNA fragmentation in Leishmania amazonensis amastigotes.
abstract: Resistance to leishmanial infections depends on intracellular parasite killing by activated host macrophages through the L-arginine-nitric oxide (NO) metabolic pathway. Here we investigate the cell death process induced by NO for the intracellular protozoan Leishmania amazonensis. Exposure of amastigotes to moderate concentrations of NO-donating compounds (acidified sodium nitrite NaNO(2) or nitrosylated albumin) or to endogenous NO produced by lipopolysaccharide or gamma interferon treatment of infected macrophages resulted in a dramatic time-dependent cell death. The combined use of several standard DNA status analysis techniques (including electrophoresis ladder banding patterns, YOPRO-1 staining in flow cytofluorometry, and in situ recognition of DNA strand breaks by TUNEL [terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling] assay) revealed a rapid and extensive fragmentation of nuclear DNA in both axenic and intracellular NO-treated amastigotes of L. amazonensis. Despite some similarities to apoptosis, the nuclease activation responsible for characteristic DNA degradation was not under the control of caspase activity as indicated by the lack of involvement of cell-permeable inhibitors of caspases and cysteine proteases. In contrast, exposure of NO-treated amastigotes with specific proteasome inhibitors, such as lactacystin or calpain inhibitor I, markedly reduced the induction of the NO-mediated apoptosis-like process. These data strongly suggest that NO-induced oligonucleosomal DNA fragmentation in Leishmania amastigotes is, at least in part, regulated by noncaspase proteases of the proteasome. The determination of biochemical pathways leading up to cell death might ultimately allow the identification of new therapeutic targets.
authors.affiliation: UR 008 Pathogénie des Trypanosomatidés, Institut de Recherche pour le Développement, 34032 Montpellier Cedex 1, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Holzmuller
authors.forename: Denis
authors.initials: D
authors.lastname: Sereno
authors.forename: Mireille
authors.initials: M
authors.lastname: Cavaleyra
authors.forename: Isabelle
authors.initials: I
authors.lastname: Mangot
authors.forename: Sylvie
authors.initials: S
authors.lastname: Daulouede
authors.forename: Philippe
authors.initials: P
authors.lastname: Vincendeau
authors.forename: Jean-Loup
authors.initials: JL
authors.lastname: Lemesre
mesh_terms: D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D053938:DNA Fragmentation; D016054:DNA, Protozoan / Q000187:drug effects; D005260:Female; D006023:Glycoproteins / Q000494:pharmacology; D007700:Kinetics; D007894:Leishmania mexicana / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D007976:Leupeptins / Q000494:pharmacology; D051379:Mice; D008807:Mice, Inbred BALB C; D009097:Multienzyme Complexes / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex; D012977:Sodium Nitrite / Q000494:pharmacology; D013997:Time Factors
chemical_list: D015853:Cysteine Proteinase Inhibitors; D016054:DNA, Protozoan; D006023:Glycoproteins; D007976:Leupeptins; D009097:Multienzyme Complexes; D020030:Nitric Oxide Donors; C039304:calpain inhibitors; C089486:carbobenzoxy-leucyl-leucyl-norvalinal; C067713:lactacystin; D009569:Nitric Oxide; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; D012977:Sodium Nitrite; D000111:Acetylcysteine