Progression to Infectivity in Trypanosoma cruzi Mediated by the RNA Binding Protein UBP1 through Translational Repression

FRASCH ALBERTO C; CASSOLA ALEJANDRO; ROMANIUK MARIA ALBERTINA

New orleans, LA

Encuentro; ASM Microbe 2017; 2017

American Society for Microbiology

Background: Trypanosoma cruzi is a flagellated protozoon that causes Chagas Disease. In trypanosomes, gene expression is mainly regulated at the posttranscriptional level by RNA-binding proteins (RBPs). Developmental progression between replicative non-infectious and non-replicative infectious forms largely depends on programs varying gene expression patterns, for which master regulators have proven to be elusive. Despite the potential roles of RBPs as master regulators of gene expression during development, we lack information on their function and possible involvement in developmental programs. Methods and results: While analyzing TcUBP1 overexpression in the non-infective stage of T. cruzi (epimastigote) using a tetracycline inducible expression system, we observed cell growth arrest and a phenotype consistent with the initiation of differentiation to the infective form (metacyclics), including repositioning of the kinetoplast to the posterior pole of the cell. The possible progression to an infective form was confirmed by the expression of trans-sialidase (a virulence protein marker of the metacyclic and trypomastigote infective forms) in epimastigotes and intermediate forms by Western blot and immunofluorescence. In order to elucidate the mechanism of action of TcUBP1 that could be causing these effects, we developed an in vivo reporter system to tether this RBP to the 3? untranslated region (UTR) of a reporter mRNA coding for luciferase. Using this system, we found that TcUBP1 represses translation of its bound mRNA. TcUBP1 involvement in global translational repression was confirmed by puromycin incorporation into nascent proteins using an anti-puromycin antibody. Conclusions: Our results allow us to establish for the first time the effect of a single RBP in the differentiation process to infective forms in T. cruzi by acting as an important regulator of gene expression.