MicroRNAs: master regulators in host–parasitic protist interactions

Abstract

MicroRNAs (miRNAs) are a group of small non-coding RNAs present in a wide diversity of organisms. MiRNAs regulate gene expression at a post-transcriptional level through their interaction with the 3′ untranslated regions of target mRNAs, inducing translational inhibition or mRNA destabilization and degradation. Thus, miRNAs regulate key biological processes, such as cell death, signal transduction, development, cellular proliferation and differentiation. The dysregulation of miRNAs biogenesis and function is related to the pathogenesis of diseases, including parasite infection. Moreover, during host–parasite interactions, parasites and host miRNAs determine the probability of infection and progression of the disease. The present review is focused on the possible role of miRNAs in the pathogenesis of diseases of clinical interest caused by parasitic protists. In addition, the potential role of miRNAs as targets for the design of drugs and diagnostic and prognostic markers of parasitic diseases is also discussed.

Roles of microRNAs and Long Non-Coding RNAs Encoded by Parasitic Helminths in Human Carcinogenesis

“…Their expressional profiles are distinct in different tissues [ 16 ]. Most miRNAs can be transcribed by RNA polymerase II or III, generating primary precursor miRNAs (pri-miRNAs) [ 17 ], which can be processed through the canonical or non-canonical pathways [ 18 ]. miRNAs can be intragenic or intergenic based on their position throughout the genome.…”

“…Additionally, miRNAs can be organized as single RNAs or as groups of RNAs (clusters). miRNA clusters can be transcribed polycistronically, which allows the coordinated regulation of complex biological processes and functional redundancy in some cases [ 18 ]. Generally, miRNAs bind the 3′-(UTR) untranslated region of messenger RNA (mRNA) to suppress expression [ 15 ], but they can also bind to the 5′-UTR region of mRNA to stimulate gene expression [ 16 ].…”

“…Generally, miRNAs bind the 3′-(UTR) untranslated region of messenger RNA (mRNA) to suppress expression [ 15 ], but they can also bind to the 5′-UTR region of mRNA to stimulate gene expression [ 16 ]. miRNAs perform their functions mainly in the cytoplasm; however, miRNAs also can be localized in other compartments such as the nucleus, mitochondria, endoplasmic reticulum, and Golgi apparatus [ 18 ].…”

“…Changes in host miRNA expressional profiles during the course of infectious diseases have been widely reported [ 18 , 20 ]; these changes have been associated with impaired host biological functions. The miRNAs of parasites also change their expression patterns in concordance with the relevant biological processes of the pathogens, and they are influenced by the host microenvironment.…”

microRNAs: Critical Players during Helminth Infections

“…MiRNAs are a group of ncRNAs (about 18–25 nucleotides) that regulate gene expression at the post-transcriptional level through their interaction with the 3′ untranslated regions of target mRNAs, promoting translational inhibition or mRNA destabilization and degradation. In addition, they regulate various biological processes, such as cell death, signal transduction, development, homeostasis, cellular proliferation, and differentiation [ 14 , 15 ]. Thus, miRNAs play an important role during host–pathogen interactions, modulating many biological aspects in the pathogen and host cells [ 15 , 16 , 17 ].…”