Intracellular heme levels modulates TcHTE expression in Trypanosoma cruzi

EVELYN TEVERE; LUCAS PAGURA; JULIA A. CRICCO; BRENDA A. CIRULLI

Caxambú

Congreso; XXXIII Meeting of the Brazilian Society of Protozoology/XLIV Annual Meeting on Basic Research in Chagas disease; 2017

Sociedad Brasilera de Protozoología - SBPz

Trypanosoma cruzi lacks a heme biosynthesis pathway, then the heme quota should be covered by its incorporation from the hosts. Our group is interested in elucidating how T. cruzi takes heme from different hosts, how its transport is regulated and how it is distributed inside the cell. We clearly showed that T. cruzi is able to import heme during the replicative life-cycle stages and also identified a protein, TcHTE, that is involved in heme transport (Merli, 2016). TcHTE, member of the HRG family and located in the flagellar pocket, can modulate heme uptake in epimastigotes. When heme availability was altered during epimastigotes? growth, TcHTE protein and mRNA levels also changed. TcHTE protein was almost no detected when epimastigotes were grown in a medium with sufficient heme (5 M or higher). However, when heme was depleted (less than 5 M), TcHTE level increased and the accumulation of its mRNA was higher compared to values obtained in a heme sufficient medium. Besides, we studied heme uptake by growing epimastigotes in presence of hemin and heme fluorescent analogs (HAs) following its incorporation by fluorescent confocal microscopy and total fluorescence measurements. We found that not all tested HAs were imported by epimastigotes. Those HAs that were incorporated (ZnPP, ZnMP and GaPP), negatively affected epimastigotes? growth due to their toxicity, and also reduced TcHTE accumulation. On the other hand, SnMP, the only analog that was not incorporated by the parasite, did not affect epimastigotes? growth and surprisingly TcHTE?s accumulation was not altered. Based on these facts, it is reasonable to postulate that T. cruzi presents a specific transport system responsible for heme uptake that can differentiate structurally similar compounds. TcHTE protein, is a relevant protein that promotes and/or regulate heme uptake, where its mRNA and protein levels respond to intracellular heme availability.