Riboflavin uptake: possible new trypanocidal targets

BALCAZAR DE; BONOMI HR; VANRELL MC; ROMANO PS; GOLDBAUM FA; CARRILLO C

Mar del Plata

Congreso; X Congreso Argentino de Protozoología y Enfermedades Parasitarias; 2014

Sociedad Argentina de Protozoologìa

Chagas disease is a parasitosis endemic in Latin-America, caused by infection with a protozoan, Trypanosoma cruzi. The current drug treatments are highly toxic, possess limited efficacy and can generate resistance, thus there is a need to identify targets to develop new therapies. Riboflavin (Rf), an essential vitamin for all living cells, is the precursor of the cofactors flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) responsible of a variety of vital cellular reactions. Plants, fungi and prokaryotes synthesize it de novo while metazoans obtain it from their diet. Our previous findings show that T. cruzi also incorporates Rf through a putative Rf transporter (?RibTCR?), identified by in silico analyses. The aim of this work was to evaluate the role of Rf in different stages of the parasite life cycle. Assays performed in T. cruzi epimastigote cultures showed that flavins stimulate their proliferation (43%) and metacyclogenesis (98%) while Rf chemical analogues significantly inhibit these processes (50% and 45%, respectively). Moreover, the proliferative capacity of epimastigotes, reduced by the analogues, was restored by the addition of high concentrations of Rf, FMN or FAD. Epimastigotes over-expressing RibTCR improved their proliferative rate in Rf limited media compared with the wild-type counterpart. The inhibitory effect of Rf analogues in the overexpressing strain was out-competed by Rf, FMN and FAD more efficiently than in the wild-type strain. Finally, analogues significantly reduced (25%) the intracellular amastigotes proliferation in cardiomyocyte monolayer infectivity model, although the infectivity of trypomastigotes was unaffected. In conclusion, Rf is a key metabolite involved in several relevant biological processes of the parasite. Our findings suggest that RibTCR is an essential protein involved in development and survival of T. cruzi. We propose Rf metabolism and uptake as potential anti-chagasic target.