Thiol efflux mediated by an ABCC-like transporter participates for Trypanosoma cruzi adaptation to environmental and chemotherapeutic stresses
The protozoan Trypanosoma cruzi is the etiologic agent for Chagas disease, which affects 6-7 million people worldwide. The parasite presents high biological diversity, reflecting on the inefficiency of benznidazole in chronic or older patients. ABC superfamily proteins contain active transporters involved in the xenobiotic and endobiotic efflux and overexpressed in MDR cells. An ABCC-like transport was identified in the T. cruzi Y strain, being able to extrude thiol-conjugated compounds. As non-protein thiols represent prime line of defense towards reactive species, ABCC-like activity could participate in the regulation of mediators implicated in responses to cellular stress arising from a variety of stimuli, as environmental or chemotherapeutic. This study shows that T. cruzi ABCC-like protein transports GSH, GSSG and ceramides, all implicated in cellular stress. Hemin, representative from the hematophagous feeding of the vector, was transported as well, suggesting a role for ABCC as a metal-thiol transporter. In addition, all strains evaluated showed ABCC-like activity, while no ABCB1-like activity was detected. Also, results suggest that ABCC-like does not associate to natural resistance to benznidazole, considering that the sensitive strains CL Brener and Berenice showed higher ABCC-like activity than the resistant strains Y and Colombiana. Instead, ABCC-like efflux increased after continuous exposure of Y strain to benznidazole. Moreover, ABCC does not perform direct efflux of drug and its participation in the machinery of protection against stress depends on the efflux of metabolites in conjugation to or in cotransport with thiol.