title: Crucial role of cytosolic tryparedoxin peroxidase in Leishmania donovani survival, drug response and virulence.
abstract: Leishmania donovani, the causative agent of visceral leishmaniasis, uses a cascade of enzymes that include cytosolic tryparedoxin peroxidase (cTXNPx) for detoxification of peroxides, an event pivotal for survival of digenic parasites living in two disparate biological environments. In this study, we observed an increase in promastigote cTXNPx levels after exposure to H(2)O(2) and this group did not show any cell death; however, exposure to a combination of H(2)O(2) and nitric oxide resulted in significant reduction of cTXNPx levels accompanied by high cell death. The protective relationship between higher levels of cTXNPx and survival was further substantiated by the improved ability of L. donovani promastigotes overexpressing cTXNPx to withstand exposure to H(2)O(2) and nitric oxide combination as compared with vector transfectants. In addition, cTXNPx transfectants demonstrated increased virulence, causing higher parasite burden in macrophages as compared with vector transfectants. Interestingly, the cTXNPx transfectants as promastigotes or amastigotes were resistant to clearance by the anti-leishmanial drug antimony, suggesting a cTXNPx link to drug response. Mechanistically, cTXNPx overexpression was protective against changes in Ca(2+) homeostasis but not against mitochondrial hyperpolarization brought about by exposure to H(2)O(2) and nitric oxide. Therefore, this study provides a link between cTXNPx expression to survival, virulence and drug response in L. donovani.
authors.affiliation: National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110067, India.
authors.forename: Jitesh P
authors.initials: JP
authors.lastname: Iyer
authors.forename: Anees
authors.initials: A
authors.lastname: Kaprakkaden
authors.forename: Manohar L
authors.initials: ML
authors.lastname: Choudhary
authors.forename: Chandrima
authors.initials: C
authors.lastname: Shaha
mesh_terms: D000818:Animals; D000965:Antimony / Q000494:pharmacology; D000981:Antiprotozoal Agents / Q000494:pharmacology; D002118:Calcium / Q000032:analysis; D002460:Cell Line; D002470:Cell Survival; D003600:Cytosol / Q000737:chemistry; D004351:Drug Resistance; D004926:Escherichia coli / Q000235:genetics; D018628:Gene Dosage; D020869:Gene Expression Profiling; D006861:Hydrogen Peroxide / Q000633:toxicity; D007893:Leishmania donovani / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology* / Q000472:pathogenicity*; D008264:Macrophages / Q000469:parasitology; D051379:Mice; D008954:Models, Biological; D009569:Nitric Oxide / Q000633:toxicity; D018384:Oxidative Stress; D010544:Peroxidases / Q000235:genetics / Q000378:metabolism*; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects; D037521:Virulence Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000981:Antiprotozoal Agents; D015800:Protozoan Proteins; D011994:Recombinant Proteins; D037521:Virulence Factors; D009569:Nitric Oxide; D000965:Antimony; D006861:Hydrogen Peroxide; D010544:Peroxidases; C110959:tryparedoxin peroxidase; D002118:Calcium