SNAREs of the endocytic pathway are involved in the biogenesis of the Trypanosoma cruzi parasitophorous vacuole

CUETO JA; VANRELL MC; CASASSA AF; ROMANO PS

Caxambu, Minas Gerais

Congreso; XXX Annual Meeting of the Brazilian Society of Protozoology / XLI Annual Meeting on Basic Research in Chagas Disease; 2014

Brazilian Society of Protozoology

Trypanosoma cruzi is the protozoan parasite that causes human Chagas disease. As an obligate intracellular parasite, T. cruzi resides transiently in a parasitophorous vacuole (TcPV). It is well established that TcPV must fuse with lysosomes of the host cell to establish a productive intracellular infection. SNAREs proteins are key molecules of the vesicle fusion machinery. The goal of this study is to identify SNAREs proteins involved in the parasite infection of non-professional phagocytic cells. Our results indicated that, after 3 hours of infection, large amount of the TcPV population were decorated with EGFP-Vamp7 in a patchy pattern (68.7% ± 12.2%). It is worthy to note that, Vamp7 is localized on lysosomes and is involved in the fusion of these organelles with different target membranes. However, EGFP-Vamp3, which regulates fusion of recycling/early endosomes with plasma membrane, was only detected in a minor fraction of the vacuoles (30.2% ± 15.0%). EGFP-Vamp8, involved in the homotypic fusion between late endosomes, was not detected. The kinetics of Vamp3 and Vamp7 association with TcPV showed different pattern throughout the course of the infection. Although both SNAREs were highly recruited at early infection times (15 min), Vamp7 increased during the first 6 hours whereas Vamp3 declined. Interestingly, Vamp7 overexpression increased twofold the parasite infection rate while siRNA silencing of Vamp7 caused a marked decrease in the infection rate. In addition, we have detected some Vamp7 cognate partners (Vti1b, Snap23 and Stx3) in the vacuole membrane. Taken together, these results indicate that Vamp7 plays a major role in TcPV biogenesis, probably by enabling the interaction with the endolysosomal compartment.