mRNA localization: a possible role in the regulation of stage-specific gene expression during Trypanosoma cruzi development

DE GAUDENZI, JAVIER G.; SABALETTE, KARINA B.; CAMPO, VANINA A.

Virtual

Congreso; Annual Molecular Parasitology Meeting; 2020

Genetics Society of America

Trypanosoma cruzi, the causative agent of Chagas disease, is characterized by regulating its gene expression mainly at post-transcriptional level. RNA regulons consist of ribonucleoprotein complexes having mRNAs whose protein products act cooperatively in a particular biological pathway. These clusters are regulated by one or more RNA-binding proteins (RBPs), thereby enabling quick changes of the protein cellular profile in response to internal or external stimuli. Previous results demonstrated that the small trypanosome-exclusive protein U-rich RBP 1 (TcUBP1) is involved in metacyclogenesis and exerts its function through the interaction with numerous mRNAs encoding cell-surface glycoproteins preferentially expressed in the trypomastigote infective stage, including members of the transialidase and trans-sialidase-like (TcS) multigenic family. The aim of this study was to evaluate if mRNA localization is a mechanism for stage-specific gene regulation. Using RNA FISH with a specific Cy3-oligo probe for TcS transcripts, we observed that over-expression of TcUBP1-GFP in epimastigotes resulted in changes in the localization of these mRNAs from the posterior region to the peri-nuclear region of the cell, as is typically observed in trypomastigotes. To get a deep insight into this result we used the wild-type T. cruzi CL-Brener strain and performed a trypomastigote-to-epimastigote differentiation in vitro. In this case we observed the relocalization of the transcripts from peri-nuclear region to the posterior region, and the same change was observed for transcripts of another cell-surface protein family named TASV, highly expressed in trypomastigotes. Indirect immunofluorescence labeling of epimastigote cells with an anti-TcCruzipain polyclonal serum detected both mRNAs families in a subcellular region that matches to reservosomes, an organelle absent in infective stages. The results obtained suggest that RNA mobilization appears to operate in the regulation of stage-specific gene expression, where the reservosome could play a role in storing and protecting mRNAs during the epimastigote replicative stage. Finally, applying bioinformatic tools, we focused on putative cis-acting RNA regulatory elements located in both TcS and TASV 3?UTRs and identified novel interacting candidates involved in this mRNA translocation.