Deciphering molecular mechanisms of mRNA metabolism in the deep‐branching eukaryote Entamoeba histolytica

Abstract

Although extraordinary rapid advance has been made in the knowledge of mechanisms regulating messenger RNA (mRNA) metabolism in mammals and yeast, little information is known in deep-branching eukaryotes. The complete genome sequence of Entamoeba histolytica, the protozoan parasite responsible for human amoebiasis, provided a lot of information for the identification and comparison of regulatory sequences and proteins potentially involved in mRNA synthesis, processing, and degradation. Here, we review the current knowledge of mRNA metabolism in this human pathogen. Several DNA motifs in promoter and nuclear factors involved in transcription, as well as conserved polyadenylation sequences in mRNA 3'-untranslated region and possible cleavage and polyadenylation factors, are described. In addition, we present recent data about proteins involved in mRNA decay with a special focus on the recently reported P-bodies in amoeba. Models for mechanisms of decapping and deadenylation-dependent pathways are discussed. We also review RNA-based gene silencing mechanisms and describe the DEAD/DExH box RNA helicases that are molecular players in all mRNA metabolism reactions. The functional characterization of selected proteins allows us to define a general framework to describe how mRNA synthesis, processing, and decay may occur in E. histolytica. Taken altogether, studies of mRNA metabolism in this single-celled eukaryotic model suggest the conservation of specific gene expression regulatory events through evolution.

mRNA Polyadenylation Machineries in Intestinal Protozoan Parasites

“…; López‐Camarillo et al. ). The 50 kDa subunit of EhCstF was deleted since reciprocal BLAST searches in the human database did not confirm its identity, while the EhPABP2 protein was added.…”

Recent advances in Entamoeba biology: RNA interference, drug discovery, and gut microbiome

“…Forward-genetic screens have helped determine the target genes regulated by specific signaling transduction pathways 26 . Additionally, transcriptome analyses in Entamoeba have helped to identify cis-elements and trans-acting factors involved in regulating gene expression 27, 28 . However, despite ongoing efforts, only a handful of DNA motifs and transcription factors have thus far been characterized 29 .…”

Proteomic analysis identifies endoribouclease EhL-PSP and EhRRP41 exosome protein as novel interactors of EhCAF1 deadenylase

“…Dis3 (RRP44) is the catalytic subunit responsible for both 3′ → 5′ exonucleolytic and endonucleolytic activities in yeast and human [20,50]. A recent study reported that E. histolytica contains seven exosome genes including Rrp41, Rrp43, Rrp46, Mtr3-Rrp42 and the catalytic subunit Dis3, as well as accessory stabilizing Rrp4, and Rrp40 proteins; but it lacks Rrp45 and Csl4 genes [30]. Because ribonucleases of exosome machinery are involved in the 3′ to 5′ decay of deadenylated transcript following CAF1-mediated deadenylation of transcripts, we decided to investigate the colocalization of EhRRP41 and EhL-PSP in trophozoites.…”

“…Recently, we have reported that mRNA decay machineries, including mainly decapping and deadenylation activities are generally well conserved in E. histolytica [30]. We also evidenced that several proteins involved in mRNA degradation, namely the EhXRN2 exoribonuclease, the EhDCP2 decapping enzyme, the EhCAF1 deadenylase and the EhAGO2-2 protein involved in RNA interference, are enriched in cytoplasmic P-body like structures in trophozoites [30,31]. Because of the relevance of poly(A) tail removal in mRNA decay, it is of prime interest to characterize the enzymes involved in deadenylation as they are likely to be target of regulators affecting mRNA stability.…”