a1 Departamento de Microbiologia Geral, Instituto de Microbiologia Prof. Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil
a2 Laboratório de Biologia Molecular e Doenças Endêmicas, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
a3 Laboratório de Genômica Funcional e Bioinformática e Laboratório de Biologia Computacional e Sistemas, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
In this paper, we aimed to explore the effects of the calpain inhibitor III (MDL28170) and to detect calpain-like molecules (CALPs) in epimastigote forms of Trypanosoma cruzi isolate Dm28c. MDL28170 at 70 μM promoted a powerful reduction in the growth rate after 48 h. The IC50 value was calculated to be 31·7 μM. This inhibitor promoted an increase in the cellular volume, but not cell lysis, resulting in a trypanostatic effect. T. cruzi CALPs presented a strong cross-reactivity with anti-Drosophila melanogaster calpain and anti-cytoskeleton-associated protein from Trypanosoma brucei antibodies, and labelling was found mainly intracellularly. Furthermore, an 80 kDa reactive protein was detected by Western blotting assays. No significant cross-reactivity was found with anti-human brain calpain antibody. The expression of CALPs was decreased in cells kept for long periods in axenic cultures in comparison to a strain recently isolated from mice, as well as in MDL28170-treated cells, the latter being paralleled by an increased expression of cruzipain. Different levels of CALPs expression were also detected in distinct phylogenetic lineages, like Y strain (lineage TCI), Dm28c (TCII) and INPA6147 strain (Z3 zymodeme). These results may contribute for the investigation of the functions of CALPs in trypanosomatids.
(Received November 14 2008)
(Revised December 26 2008)
(Revised January 08 2009)
(Accepted January 09 2009)
(Online publication March 02 2009)
c1 Corresponding author: Departamento de Microbiologia Geral, Instituto de Microbiologia Prof. Paulo de Góes, Universidade Federal do Rio de Janeiro (UFRJ), Centro de Ciências da Saúde (CCS), Av. Carlos Chagas Filho, 373, Bloco I, Cidade Universitária, Rio de Janeiro, RJ, 21941-902, Brazil. Tel: +55 21 2562 6743. Fax: +55 21 2560 8344. E-mail: firstname.lastname@example.org
# These authors contributed equally to the work.