title: Novel strategy in Trypanosoma cruzi cell invasion: implication of cholesterol and host cell microdomains.
abstract: Trypanosoma cruzi, the etiological agent of Chagas' disease, is an obligatory intracellular parasite in the mammalian host. In order to invade a wide variety of mammalian cells, T. cruzi engages parasite components that are differentially expressed among strains and infective forms. Because the identification of putative protein receptors has been particularly challenging, we investigated whether cholesterol and membrane rafts, sterol- and sphingolipid-enriched membrane domains, could be general host surface components involved in invasion of metacyclic trypomastigotes and extracellular amastigotes of two parasite strains with distinct infectivities. HeLa or Vero cells treated with methyl-beta-cyclodextrin (MbetaCD) are less susceptible to invasion by both infective forms, and the effect was dose-dependent for trypomastigote but not amastigote invasion. Moreover, treatment of parasites with MbetaCD only inhibited trypomastigote invasion. Filipin labeling confirmed that host cell cholesterol concentrated at the invasion sites. Binding of a cholera toxin B subunit (CTX-B) to ganglioside GM1, a marker of membrane rafts, inhibited parasite infection. Cell labeling with CTX-B conjugated to fluorescein isothiocyanate revealed that not only cholesterol but also GM1 is implicated in parasite entry. These findings thus indicate that microdomains present in mammalian cell membranes, that are enriched in cholesterol and GM1, are involved in invasion by T. cruzi infective forms.
authors.affiliation: Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de São Paulo, Escola Paulista de Medicina, Rua Botucatu, São Paulo, SP, Brazil.
authors.forename: Maria Cecília
authors.initials: MC
authors.lastname: Fernandes
authors.forename: Mauro
authors.initials: M
authors.lastname: Cortez
authors.forename: Kelly Aparecida
authors.initials: KA
authors.lastname: Geraldo Yoneyama
authors.forename: Anita Hilda
authors.initials: AH
authors.lastname: Straus
authors.forename: Nobuko
authors.initials: N
authors.lastname: Yoshida
authors.forename: Renato Arruda
authors.initials: RA
authors.lastname: Mortara
mesh_terms: D000818:Animals; D002522:Chlorocebus aethiops; D002772:Cholera Toxin / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism*; D005677:G(M1) Ganglioside / Q000031:analogs & derivatives / Q000378:metabolism; D006367:HeLa Cells; D006790:Host-Parasite Interactions; D006801:Humans; D014349:Trypanosoma cruzi / Q000187:drug effects / Q000472:pathogenicity*; D014709:Vero Cells / Q000469:parasitology*; D047392:beta-Cyclodextrins / Q000494:pharmacology
chemical_list: D047392:beta-Cyclodextrins; C502266:ganglioside GM1alpha; C108732:methyl-beta-cyclodextrin; D005677:G(M1) Ganglioside; D002772:Cholera Toxin; D002784:Cholesterol