title: Starvation and rapamycin differentially regulate host cell lysosome exocytosis and invasion by Trypanosoma cruzi metacyclic forms.
abstract: The molecular mechanisms of host cell invasion by T. cruzi metacyclic trypomastigotes (MT), the developmental forms that initiate infection in the mammalian host, are only partially understood. Here we aimed at further identifying the target cell components involved in signalling cascades leading to MT internalization, and demonstrate for the first time the participation of mammalian target of rapamycin (mTOR). Treatment of human epithelial HeLa cells with mTOR inhibitor rapamycin reduced lysosomal exocytosis and MT invasion. Downregulation of phosphatidylinositol 3-kinase and protein kinase C also impaired exocytosis and MT internalization. The recombinant protein based on gp82, the MT surface molecule that mediates cell adhesion/invasion, induced exocytosis in HeLa cells. Such an effect has not previously been attributed to any T. cruzi surface molecule. Rapamycin treatment diminished gp82 binding as well. Cell invasion assays under conditions that promoted lysosome exocytosis, such as 1 h incubation in starvation medium PBS(++) , increased MT invasion, whereas pre-starvation of cells for 1-2 h had an opposite effect. In contrast to MT, invasion of tissue culture trypomastigotes (TCT) increased upon host cell pre-starvation or treatment with rapamycin, a novel finding that discloses quite distinctive features of the two infective forms in a key process for infection.
authors.affiliation: Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, Rua Botucatu 862, São Paulo, Brazil.
authors.forename: Rafael Miyazawa
authors.initials: RM
authors.lastname: Martins
authors.forename: Renan Melatto
authors.initials: RM
authors.lastname: Alves
authors.forename: Silene
authors.initials: S
authors.lastname: Macedo
authors.forename: Nobuko
authors.initials: N
authors.lastname: Yoshida
mesh_terms: D004791:Enzyme Inhibitors / Q000378:metabolism; D005089:Exocytosis / Q000187:drug effects*; D006367:HeLa Cells; D054884:Host-Pathogen Interactions; D006801:Humans; D008247:Lysosomes / Q000187:drug effects / Q000469:parasitology*; D008954:Models, Biological; D058539:Phosphatidylinositol 3-Kinase / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D015800:Protozoan Proteins / Q000378:metabolism*; D020123:Sirolimus / Q000378:metabolism*; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014349:Trypanosoma cruzi / Q000472:pathogenicity*; D014643:Variant Surface Glycoproteins, Trypanosoma / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D000081082:Phosphoinositide-3 Kinase Inhibitors; D015800:Protozoan Proteins; D014643:Variant Surface Glycoproteins, Trypanosoma; C527132:glycoprotein GP82, Trypanosoma cruzi; C546842:MTOR protein, human; D058539:Phosphatidylinositol 3-Kinase; D058570:TOR Serine-Threonine Kinases; D011493:Protein Kinase C; D020123:Sirolimus