The zinc finger protein TcZFP2 binds target mRNAs enriched during Trypanosoma cruzi metacyclogenesis

Abstract

Trypanosomes are parasitic protozoa in which gene expression is primarily controlled through the regulation of mRNA stability and translation. This post-transcriptional control is mediated by various families ofIn eukaryotes, post-transcriptional regulation involves cis control elements, which are generally present in the untranslated regions (UTRs) of mRNAs and trans-acting factors, such as non-coding RNAs and RNA-binding proteins (RBPs). RBPs are major regulators of mRNA processing, transport, stability and translation and are classified according to their RNA-binding domains (Lunde et al. 2007). Proteins with zinc finger domains may interact either with other proteins or with nucleic acids. Zinc finger domains with CCCH motifs bind to RNAs with high affinity and are present in proteins that are involved in the post-transcriptional regulation of mRNAs (Auweter et al. 2006). RBPs of this class have been identified in trypanosomatid protozoan parasites, which have been shown to contain approximately 50 proteins with at least one zinc finger domain (Hendricks & Matthews 2007, Kramer et al. 2010). Several species of trypanosomatids cause various diseases in humans and domestic animals, with major impacts on human health and on the economies of developing countries. The implicated species include Trypanosoma cruzi, Trypanosoma brucei spp and Leishmania spp. T. cruzi is the causal agent of Chagas disease, which affects millions of people in the Americas. This parasite has a complex life cycle, with two hosts and at least four well-defined forms (de Souza 2002). Within the insect vector, the non-infectious replicative forms (epimastigotes) are converted into non-replicating infectious forms (metacyclic trypomastigotes) in a process called metacyclogenesis. This differentiation process can be mimicked in vitro through the use of well-defined chemical media (Contreras et al. 1985(Contreras et al. , 1988 and this system constitutes an excellent model for studying differential gene expression throughout the life cycle of the parasite.Gene expression is controlled almost entirely by posttranscriptional regulation in trypanosomes (reviewed by Clayton & Shapira 2007). This regulation typically involves polycistronic transcription, mRNA maturation by trans-splicing and the editing of mitochondrial transcripts. No canonical RNA pol II promoters have been described and a clear case in which transcription initiation is regulated for this polymerase has yet to be reported. Moreover, genes that are present in the same polycistronic unit and transcribed as a single pre-mR-NA display different patterns of expression, suggesting that regulation occurs during the later stages of mRNA metabolism. Post-transcriptional regulation in trypanoputative RNA targets of protein TcZFP2 • Patricia Alves Mörking et al. 791somes has been reported to primarily involve the control of mRNA stability and translation. The exosome and deadenylation complexes have been identified as the primary regulators of transcript stability via several different deg...

Genome-wide analysis of 3′-untranslated regions supports the existence of post-transcriptional regulons controlling gene expression in trypanosomes

“…In the past few years several reports provided evidence indicating that trypanosomal transcripts are organized as post-transcriptional regulons (Archer et al, 2009; Das et al, 2012; Estevez, 2008; Guerra-Slompo et al, 2012; Mayho et al, 2006; Noe, De Gaudenzi & Frasch, 2008). Furthermore, several RBPs have also been shown to interact with a subset of stage-specific mRNAs, suggesting the presence of developmental regulons (Dallagiovanna et al, 2008; Li et al, 2012; Mörking et al, 2012; Walrad et al, 2012). …”

RNA in development: how ribonucleoprotein granules regulate the life cycles of pathogenic protozoa

“…Almost nothing is known about the function of RNP granules during the Trypanosomatidae life cycles. Of the several RNA‐binding proteins that were reported or suggested to participate in life‐cycle regulation, four, ALBA3 and 4, DHH1 and Tc PUF6 are also present in RNA granules, providing at least an indirect connection between RNP granules and life cycle regulation.…”

“…Almost nothing is known about the function of RNP granules during the Trypanosomatidae life cycles. Of the several RNA-binding proteins that were reported or suggested to participate in life-cycle regulation, 128,149,159,[174][175][176][177][178][179] four, ALBA3 and 4, 159,160 DHH1 148,150 and TcPUF6 149 are also present in RNA granules, providing at least an indirect connection between RNP granules and life cycle regulation. ALBA 3 and 4 protein expression is transiently reduced during the differentiation of the non-proliferative mesocyclic to the epimastigote T. brucei forms, a differentiation that occurs in the tsetse fly proventriculus 159 (Figure 3(a)).…”

The mRNAs associated to a zinc finger protein fromTrypanosoma cruzishift during stress conditions

“…However, only a few of these proteins have been characterized to date 11 . In T. cruzi , TcZFP1 has been shown to bind preferentially to C-rich regions, 12 whereas TcZFP2 has a higher affinity for A-rich regions and the mRNAs associated with this protein appear to be upregulated in metacyclic trypomastigotes, suggesting a possible role in parasite differentiation 13 . In T. brucei , the characterized zinc finger proteins are associated with parasite differentiation from the procyclic to bloodstream forms 14 - 17 and the stability of their mRNA targets 18 - 20 …”