Parasitology Research

, Volume 115, Issue 8, pp 3057–3069 | Cite as

The fungal metabolite gliotoxin inhibits proteasome proteolytic activity and induces an irreversible pseudocystic transformation and cell death in Tritrichomonas foetus

  • Antonio Pereira-Neves
  • Rubem F. S. Menna-Barreto
  • Marlene BenchimolEmail author
Original Paper


Proteasomal proteolysis is required for a wide range of cellular processes, including protein quality control, cell cycle progression, cell death and metabolic adaptation to environment changes or stress responses. Proteasome inhibitors are useful compounds for determining the roles of proteasome in eukaryotic cells. Here, we investigated the effects of gliotoxin, a proteasome inhibitor, on the cell growth, replication, ultrastructure, DNA integrity and proteasomal proteolytic activity of the protist parasite Tritrichomonas foetus. The effect of gliotoxin on the transformation of T. foetus to endoflagellar form (EFF), also known as pseudocyst, was investigated. Gliotoxin inhibited the culture growth, arrested cell cycle, and provoked a trichomonacidal effect in a dose-dependent manner. Parasites treated with gliotoxin displayed features typical of cell death, such as membrane blebbing, concentric membrane whorls containing remnants of organelles, intense cytosolic and nuclear vacuolisation, chromatin condensation, DNA fragmentation, cytoplasmic disintegration and plasma membrane disruption. The proteasomal peptidase activity was inhibited by gliotoxin in a dose-dependent manner. Gliotoxin treatment also induced an irreversible EFF transformation in a dose/time-dependent manner. We compared morphological characteristics between gliotoxin- and cold-induced EFF parasites. Our results suggest that gliotoxin could induce EFF transformation by a mechanism distinct from that provoked by cold temperature. This study further contributes to a better understanding of the role of proteasome system in cell cycle, cell death and EFF transformation in T. foetus.


Cell replication Electron microscopy Endoflagellar form Proteasome inhibitor Trichomonosis 



This work was supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq), Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ), Programa de Núcleos de Excelência (PRONEX) and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES).

Supplementary material

436_2016_5061_Fig10_ESM.gif (275 kb)
Online Resource 1

Comparison between parasites undergoing the process of gliotoxin- and cold-induced EFF transformation by SEM. The recurrent flagellum is not externally visible. Some anterior flagella (F) are still externally visible. (a-b) Parasites were incubated with 1 μM gliotoxin for 9 h at 37 °C. EFF parasites exhibit wrinkled surface, membrane (arrows) and flagellar (asterisk) blebbing. (c-d) Parasites were incubated for 2 h at 4 °C. EFF parasites do not exhibit membrane and flagellar blebbing. Bars, a-b, c, 2 μm; d, 1 μm. (GIF 275 kb)

436_2016_5061_MOESM1_ESM.tif (1.2 mb)
High Resolution Image (TIF 1262 kb)


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Copyright information

© Springer-Verlag Berlin Heidelberg 2016

Authors and Affiliations

  • Antonio Pereira-Neves
    • 1
    • 2
  • Rubem F. S. Menna-Barreto
    • 3
  • Marlene Benchimol
    • 2
    • 4
    • 5
    Email author
  1. 1.Fiocruz Pernambuco, Centro de Pesquisa Aggeu Magalhães, Departamento de MicrobiologiaRecifeBrazil
  2. 2.Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e BioimagemUniversidade Federal do Rio de JaneiroRio de JaneiroBrazil
  3. 3.Fiocruz, Instituto Oswaldo CruzRio de JaneiroBrazil
  4. 4.UNIGRANRIO- Universidade do Grande RioDuque de CaxiasBrazil
  5. 5.Instituto de Biofísica Carlos Chagas FilhoUniversidade Federal do Rio de JaneiroRio de JaneiroBrazil

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