RNA Interference In Entamoeba Histolytica : Implications For Parasite Biology And Gene Silencing

Abstract

Entamoeba histolytica is a major health threat to people in developing countries, where it causes invasive diarrhea and liver abscesses. The study of this important human pathogen has been hindered by a lack of tools for genetic manipulation. Recently, a number of genetic approaches based on variations of the RNAi method have been successfully developed and cloning of endogenous small-interfering RNAs from E. histolytica revealed an abundant population of small RNAs with an unusual 5′-polyphosphate structure. However, little is known about the implications of these findings to amebic biology or the mechanisms of gene silencing in this organism. In this article we review the literature relevant to RNAi in E. histolytica, discuss its implications for advances in gene silencing in this organism and outline potential future directions towards understanding the repertoire of RNAi and its impact on the biology of this deep-branching eukaryotic parasite.

Regulation of gene expression in the protozoan parasite Entamoeba invadens: identification of core promoter elements and promoters with stage-specific expression patterns

“…We took a similar strategy by selecting transcripts, which showed stage-specific expression, from recent RNA-Seq data (Ehrenkaufer et al, 2013). Given that multiple mechanisms for regulating gene expression have been described in Entamoeba (transcription factor, epigenetic control and small RNA regulation) (Mirelman et al, 2008; Singh and Ehrenkaufer, 2009; Zhang et al, 2011; Morf et al, 2013), it was not clear whether stage-specific mRNA patterns would be recapitulated in stage-specific promoter activity. For the multiple promoters analyzed, we found concordant regulation of luciferase expression in a stage-specific manner, thus validating the RNA-Seq data.…”

RNA Interference in Protozoan Parasites: Achievements and Challenges

“…The only other protozoan parasite with a well-studied but still not completely understood RNAi system is E. histolytica (75). The emerging theme is that long dsRNA (or the expression of long antisense transcripts that base pair with the target to form long dsRNAs) is an excellent trigger for RNAi not only in trypanosomes but also in E. histolytica (77), G. intestinalis (51), and T. gondii (4).…”

The emerging world of small silencing RNAs in protozoan parasites

“…In contrast to Giardia, a variety of studies have provided evidence that expression or delivery of dsRNA can be used as a tool to downregulate E. histolytica gene expression [43]. Entamoeba has three predicted AGO-like proteins, one of which (EH_125650) predominates in axenically-grown parasites and is found associated with a special class of ssRNAs [43], as discussed below.…”