title: Tritrichomonas foetus: characterisation of ecto-phosphatase activities in the endoflagelar form and their possible participation on the parasite's transformation and cytotoxicity.
abstract: The protist parasite Tritrichomonas foetus displays a pear-shaped (PS) and a pseudocystic or endoflagellar form (EFF). Here, we characterised the ecto-phosphatase activity on the surface of EFF and compare its biochemical properties to that of the PS regarding rate of substrate hydrolysis, pH activation profile and sensitivity to well-known phosphatases inhibitors. Two strains exhibiting low- and high-cytotoxicity were used. The enzyme activities of PS and EFF exhibited similar characteristics of protein tyrosine phosphatases (PTP). However, the ecto-phosphatase activities for both forms presented distinct kinetic parameters and different inhibition patterns by PTP inhibitors, suggesting the presence of distinct ecto-enzyme activities between PS and EFF, as well, between both strains. Ultrastructural cytochemistry confirmed the differential distribution of the ecto-phosphatase activity during the EFF transformation. An increase in the percentage of the EFF resulted in a proportional increase in the ecto-phosphatase activity. During EFF reversion, ecto-phosphatase activity decreased and was restored to the level found in the parasites before EFF induction. PS and EFF from the high-cytotoxic strain exhibited higher ecto-phosphatase activities than PS and EFF from the low-cytotoxic strain, respectively. In both strains, the EFF was more cytotoxic and exhibited higher ecto-phosphatase activity when compared to the PS. A large part of the ecto-phosphatase activities of EFF from both strains and PS from the high-cytotoxic strain was irreversibly inhibited when the parasites were pre-treated with a specific antibody against amoebic PTP (anti-EhPRL). Immunoreaction assays revealed that the anti-EhPRL antibody cross-reacted with a 24-kDa protein differentially expressed on the cell surface of PS and EFF T. foetus. A positive correlation was observed between the surface expression of 24-kDa protein and ecto-phosphatase activity. Irreversible inhibition of a part of the ecto-phosphatase activities partially blocked the EFF induction and the cytotoxic effects exerted by both forms. These results suggest that the ecto-phosphatase activities could play a role on the EFF transformation and cytotoxicity of T. foetus.
authors.affiliation: Programa de Pós-graduação em Ciências Morfológicas da Universidade Federal do Rio de Janeiro CCS, bloco F, Cidade Universitária, Ilha do Fundão, CEP 21941-521 Rio de Janeiro, RJ, Brazil; Laboratório de Ultraestrutura Celular, Universidade Santa Úrsula, Rua Jornalista Orlando Dantas 59, Botafogo, CEP 22231-010 Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Cidade Universitária, Ilha do Fundão, CEP 21941-521 Rio de Janeiro, RJ, Brazil.
authors.forename: Antonio
authors.initials: A
authors.lastname: Pereira-Neves
authors.affiliation: Departamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del I.P.N., México D.F. 07360, Mexico.
authors.forename: José Luis
authors.initials: JL
authors.lastname: Rosales-Encina
authors.affiliation: Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Cidade Universitária, Ilha do Fundão, CEP 21941-521 Rio de Janeiro, RJ, Brazil; Laboratório de Bioquímica Celular, Instituto de Bioquímica Médica, Centro de Ciências da Saúde, Universidade Federal do Rio de Janeiro, bloco H, Cidade Universitária, Ilha do Fundão, CEP 21941-521 Rio de Janeiro, RJ, Brazil.
authors.forename: José Roberto
authors.initials: JR
authors.lastname: Meyer-Fernandes
authors.affiliation: Laboratório de Ultraestrutura Celular, Universidade Santa Úrsula, Rua Jornalista Orlando Dantas 59, Botafogo, CEP 22231-010 Rio de Janeiro, Brazil; Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Cidade Universitária, Ilha do Fundão, CEP 21941-521 Rio de Janeiro, RJ, Brazil. Electronic address: marlenebenchimol@gmail.com.
authors.forename: Marlene
authors.initials: M
authors.lastname: Benchimol
mesh_terms: D000818:Animals; D002417:Cattle; D004285:Dogs; D005455:Fluorescent Antibody Technique; D006651:Histocytochemistry; D006863:Hydrogen-Ion Concentration; D015151:Immunoblotting; D007150:Immunohistochemistry; D061985:Madin Darby Canine Kidney Cells; D008297:Male; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D016253:Microscopy, Immunoelectron; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D016835:Tritrichomonas foetus / Q000145:classification / Q000201:enzymology* / Q000648:ultrastructure
chemical_list: D010749:Phosphoprotein Phosphatases
keywords: Cytotoxicity; Ecto-enzymes; Ecto-phosphatase; Protein tyrosine phosphatase; Pseudocyst