IHEM   20887
INSTITUTO DE HISTOLOGIA Y EMBRIOLOGIA DE MENDOZA DR. MARIO H. BURGOS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Induction of autophagy promotes cruzipain processing during Trypanosoma cruzi differentiation
Autor/es:
LOSINNO AD; ROMANO PS
Lugar:
Buenos Aires
Reunión:
Congreso; Reunión Conjunta de Sociedades de Biociencias; 2017
Institución organizadora:
Sociedades Científicas (SAIC, SAIB, SAP, etc)
Resumen:
Trypanosoma cruzi is the causative agent of Chagas? disease. During its life cycle, this parasite present four developmental stages: epimastigotes, metacyclic trypomastigotes, bloodstream trypomastigotes and amastigotes. Epimastigotes contain reservosomes, organelles that accumulate proteins and lipids ingested by endocitosis. This content is digested by hidrolases to supply energy during the differentiation of epimastigotes into metacyclic trypomastigotes (metacyclogenesis). The autophagic system of T. cruzi is activated during starvation-induced stress and also during differentiation. Cruzipain is the major cysteine proteinase in T.cruzi and a key enzyme for nutrition, differentiation and for the establishment of host cell infection. Cruzipain is synthesized as a zymogen, processed and delivered to reservosomes. The aim of this work was to evaluate the participation of autophagy in the distribution and function of cruzipain during metacyclogenesis. For this, Y-wild type epimastigotes were kept in BHT medium (control) or subjected to nutritional stress by incubation for 2 h in TAU medium. Parasites were inoculated in flasks containing BHT or TAU3AAG medium and incubated for 72 h. By confocal microscopy, we observed that starvation (2 h) induces the accumulation of cruzipain in compartments located at the posterior region of the parasite. The colocalization of this compartments with Atg8 (autophagy marker), endocitic markers and DQ-BSA (indicator of proteolytic activity) increase by nutritional stress. Western blot analysis showed that the cruzipain zymogen form was recognized in both control and in starvation conditions (2 h), although the latter had decreased zymogen levels at 72 h. We detected the mature form of cruzipain and a band corresponding to the carboxyl-terminal fragment only in the starvation condition (72 h). When we used autophagy inhibitors, cruzipain does not accumulate in reservosome. The action of K777, an cruzipain inhibitor, induces a cruzipain distribution in the cell surface, avoiding their accumulation in the reservosomes and the differentiation to trypomastigotes. This findings indicate that the induction of autophagy by starvation promotes the cruzipain processing that triggers to its activation.