Intracellular compartments concentrate acid hydrolases in Trypanosoma cruzi trypomastigotes and amastigotes

CELSO SANT'ANNA; JULIANA M.F. DUTRA; EMILE BARRIAS; FABIOLA PARUSSINI; JUAN JOSÉ CAZZULO; TECIA ULISSES DE CARVALHO; WANDERLEY DE SOUZA; NARCISA CUNHA-E-SILVA

Caxambu

Congreso; XX Annual Meeting of Brazilian Society of Protozoology and XXXI Annual Meeting on Basic Research in Chagas Disease; 2004

Sociedad Brasilera de Protozoologia

Cruzipain is the major protease of Trypanosoma cruzi. It is acathepsin L-like cysteine protease synthesized as preproenzime that trafficsfrom Golgi to reservosomes where it is accumulated in epimastigotes. Recently,a lysosomal monomeric glycoprotein serine carboxypeptidase belonging to S10family was described. Its traffic needs to be better defined, but it was suggested that the serine carboxypeptidase is also accumulatedin epimastigote reservosomes. In this work, we performed the localization ofserine carboxypepetidase in T. cruzi trypomastigotes and amastigotes derived from tissue culturesupernatant. Indirect immunofluorescence using antibodies arisen against serinecarboxypeptidase and cruzipain showed co-localization of these acid hydrolases incompartments confined between nucleus and kinetoplast in trypomastigotes and inthe posterior end of amastigotes. Immunoelectronmicroscopy confirmed theco-localization and showed that these enzymes are accumulated in rounded andtubular structures. As the organelles concentrate acid hydrolases in theseforms were not described yet, we initiated their morphologicalcharacterization. They are constituted by electron lucent tubules and vesiclesheterogeneous in size and shape, surrounded by a single membrane. Their acidic character wasevidenced by incubating parasites with Lysotracker, a cell permeant acidotropicfluorophore. In T. cruzi the endocytic process was only described inepimastigotes that uptake nutrients by cytostome and flagellar pocket, storingthem in reservosomes, acidic organelles found mainly at the posterior region. Endocytic compartments were not detected in trypomastigotesor amastigotes yet. We could not observe the ingestion of bovine albumin,transferring or concanavalin A by these evolutive forms, confirming that they are not able touptake and store extracellular nutrients. Further experiments are in course toclarify whether these undescribed intracellular compartments of trypomastigotesand amastigotes participate of endocytic or exocytic pathways.