The fungal metabolite gliotoxin inhibits proteasome proteolytic activity and induces an irreversible pseudocystic transformation and cell death in Tritrichomonas foetus.
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.
Fiocruz Pernambuco, Centro de Pesquisa Aggeu Magalhães, Departamento de Microbiologia, Recife, PE, Brazil.|Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil.
Antonio
A
Pereira-Neves
Fiocruz, Instituto Oswaldo Cruz, Rio de Janeiro, RJ, Brazil.
Rubem F S
RF
Menna-Barreto
Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil. marlenebenchimol@gmail.com.|UNIGRANRIO- Universidade do Grande Rio, Duque de Caxias, RJ, Brazil. marlenebenchimol@gmail.com.|Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, Rio de Janeiro, RJ, Brazil. marlenebenchimol@gmail.com.
Marlene
M
Benchimol
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002453:Cell Cycle / Q000187:drug effects; D059447:Cell Cycle Checkpoints / Q000187:drug effects; D016923:Cell Death / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D053938:DNA Fragmentation / Q000187:drug effects; D005912:Gliotoxin / Q000494:pharmacology*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D061988:Proteasome Inhibitors / Q000494:pharmacology*; D059748:Proteolysis / Q000187:drug effects*; D016835:Tritrichomonas foetus / Q000187:drug effects / Q000378:metabolism*
D061988:Proteasome Inhibitors; D005912:Gliotoxin; D046988:Proteasome Endopeptidase Complex
Cell replication; Electron microscopy; Endoflagellar form; Proteasome inhibitor; Trichomonosis