title: Inhibition of proteasome activity blocks Trypanosoma cruzi growth and metacyclogenesis.
abstract: Proteasomes are intracellular complexes that control protein degradation in organisms ranging from Archaebacteria to mammals. In some parasitic protozoa, the proteasome is involved in cell differentiation and replication. In this study, we have used proteasome inhibitors to determine the biological role of proteasomes during the replication and in vitro metacyclogenesis of Trypanosoma cruzi. We used light and transmission electron microscopy to analyze morphological data and flow cytometry to analyze changes in the cell cycle. The growth of T. cruzi epimastigote culture forms in liver infusion tryptose medium was inhibited by the presence of up to 10 microM lactacystin. Inhibition was dose-dependent, with IC50 (50% inhibitory concentration) of 4.35 microM after 24 or 72 h. The metacyclogenesis process in vitro was strongly (95%) inhibited by 5 microM lactacystin treatment. The adhesion phase was not affected, but the epimastigotes did not differentiate into metacyclic trypomastigotes. Most treated epimastigotes had replicated DNA, with swelling of the mitochondrion and an altered distribution of nuclear and kinetoplast DNA. Our findings suggest that inhibition of the ubiquitin-proteasome pathway in T. cruzi epimastigotes does not block adhesion, but disrupts cell division and affects factors triggering differentiation.
authors.affiliation: Instituto de Biologia Molecular do Paraná, Rua Prof. Algacyr Munhoz Mader 3775, 81350-010 Curitiba, PR, Brazil.
authors.forename: Josiane
authors.initials: J
authors.lastname: Cardoso
authors.forename: Maurilio J
authors.initials: MJ
authors.lastname: Soares
authors.forename: Rubem F S
authors.initials: RF
authors.lastname: Menna-Barreto
authors.forename: Rozenn
authors.initials: R
authors.lastname: Le Bloas
authors.forename: Vanessa
authors.initials: V
authors.lastname: Sotomaior
authors.forename: Samuel
authors.initials: S
authors.lastname: Goldenberg
authors.forename: Marco A
authors.initials: MA
authors.lastname: Krieger
mesh_terms: D000111:Acetylcysteine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D002448:Cell Adhesion / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D003470:Culture Media / Q000737:chemistry; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D004261:DNA Replication / Q000187:drug effects; D018105:DNA, Kinetoplast / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D020128:Inhibitory Concentration 50; D008853:Microscopy; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000473:pathology; D061988:Proteasome Inhibitors; D013997:Time Factors; D014349:Trypanosoma cruzi / Q000166:cytology / Q000187:drug effects* / Q000254:growth & development* / Q000648:ultrastructure
chemical_list: D003470:Culture Media; D015853:Cysteine Proteinase Inhibitors; D018105:DNA, Kinetoplast; D061988:Proteasome Inhibitors; C067713:lactacystin; D000111:Acetylcysteine