Over-expression of TbRRM1 leads to aberrant phenotypes and cell death in Trypanosoma brucei procyclic cells

NÍTTOLO, AG; SÁNCHEZ, DO; LEVY, GV

Mar del Plata

Encuentro; Reunión anual de Sociedades de Biociencia; 2019

Since transcription in trypanosomatids is polycistronic, regulation of gene expression occurs mainly at the post-transcriptional level by RNA binding proteins. In our lab we study the gene expression regulation in T. brucei, particularly we focus on elucidating the function of the RNA binding protein, TbRRM1. TbRRM1 has three RRM domains in the amino-terminal region followed by two zinc finger domains and a region rich in dipeptides (Asp/Glu)-Arg which precedes the RS domain characteristic of the SR protein family. Previously, we have demonstrated that TbRRM1 is essential for survival in procyclic and bloodstream form stages of T. brucei since its silencing by RNAi affects the growth curve, produces aberrant phenotypes and promotes cell death by a mechanism compatible with apoptosis. The aim of the present work was to contribute to the elucidation of TbRRM1 function through the study of the effects of its over-expression. For that purpose, we have established a system for the inducible over-expression of a FLAG-tagged TbRRM1 and different mutants. Results showed that over-expression of 3xFLAG-TbRRM1 was deleterious for parasite survival. Surprisingly, the parasites displayed an aberrant morphology that was previously observed when TbRRM1 was depleted, suggesting that both silencing and over-expression of TbRRM1 produce a similar phenotype. In addition, since both silencing and over-expression of TbRRM1 are lethal for parasites, it could be concluded that TbRRM1 is a relevant protein whose levels must be finely regulated.