title: Evidence for a negative feedback control mediated by the 3' untranslated region assuring the low expression level of the RNA binding protein TcRBP19 in T. cruzi epimastigotes.
abstract: Because of their relevant role in the post-transcriptional regulation of the expression of a multitude of genes, RNA-binding proteins (RBPs) need to be accurately regulated in response to environmental signals in terms of quantity, functionality and localization. Transcriptional, post-transcriptional and post-translational steps have all been involved in this tight control. We have previously identified a Trypanosoma cruzi RBP, named TcRBP19, which can barely be detected at the replicative intracellular amastigote stage of the mammalian host. Even though protein coding genes are typically transcribed constitutively in trypanosomes, TcRBP19 protein is undetectable at the epimastigote stage. Here, we show that this protein expression pattern follows the steady-state of its mRNA. Using a T. cruzi reporter gene approach, we could establish a role for the 3' UTR of the tcrbp19 mRNA in transcript down-regulation at the epimastigote stage. In addition, the binding of the TcRBP19 protein to its encoding mRNA was revealed by in vitro pull down followed by qRT-PCR and confirmed by CLIP assays. Furthermore, we found that forced over-expression of TcRBP19 in T. cruzi epimastigotes decreased the stability of the endogenous tcrbp19 mRNA. These results support a negative feedback control of TcRBP19 to help maintain its very low concentration of TcRBP19 in the epimastigote stage. To our knowledge, this is the first RBP reported in trypanosomatids capable of negatively regulating its own mRNA. The mechanism revealed here adds to our limited but growing number of examples of negative mRNA autoregulation in the control of gene expression.
authors.affiliation: Laboratorio de Interacciones Moleculares, Facultad de Ciencias, Iguá 4225, 11400 Montevideo, Uruguay.
authors.forename: Leticia
authors.initials: L
authors.lastname: Pérez-Díaz
authors.forename: Lucía
authors.initials: L
authors.lastname: Pastro
authors.forename: Pablo
authors.initials: P
authors.lastname: Smircich
authors.forename: Bruno
authors.initials: B
authors.lastname: Dallagiovanna
authors.forename: Beatriz
authors.initials: B
authors.lastname: Garat
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics*; D001483:Base Sequence; D015536:Down-Regulation; D025461:Feedback, Physiological; D005786:Gene Expression Regulation; D008957:Models, Genetic; D008969:Molecular Sequence Data; D011485:Protein Binding; D015800:Protozoan Proteins / Q000235:genetics* / Q000378:metabolism; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016053:RNA, Protozoan / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014349:Trypanosoma cruzi / Q000166:cytology / Q000235:genetics* / Q000378:metabolism
chemical_list: D020413:3' Untranslated Regions; D015800:Protozoan Proteins; C581870:RBP19 protein, Trypanosoma cruzi; D012333:RNA, Messenger; D016053:RNA, Protozoan; D016601:RNA-Binding Proteins