Trans-acting proteins regulating mRNA maturation, stability and translation in trypanosomatids

Abstract

In trypanosomatids, alterations in gene expression in response to intrinsic or extrinsic signals are achieved through post-transcriptional mechanisms. In the last 20 years, research has concentrated on defining the responsible cis-elements in the untranslated regions of several regulated mRNAs. More recently, the focus has shifted towards the identification of RNA-binding proteins that act as trans-acting factors. Trypanosomatids have a large number of predicted RNA-binding proteins of which the vast majority have no orthologues in other eukaryotes. Several RNA-binding proteins have been shown to bind and/or regulate the expression of a group of mRNAs that code for functionally related proteins, indicating the possible presence of co-regulated mRNA cohorts.

Figure 1

Schematics of all CCCH-type zinc finger proteins with at least one trypanosome orthologue being experimentally characterized. (a) The small ZFP family of CCCH proteins involved in the regulation of differentiation. (b) The cycling sequence binding proteins, CCCH proteins that bind to an octameric sequence present in mRNAs that change level during the cell cycle. The T. cruzi genome strain CL Brener is a hybrid and allelic alleles have been indicated (*). Abbreviations: Tb, T. brucei; Lm, L. major; Ld, L. donovani; Tc, T. cruzi; Cf, Crithidia fasciculata.