CUCHER Marcela Alejandra
capítulos de libros
MicroRNAs in Endoparasites
MicroRNA and Non-Coding RNA: Technology, Developments and Applications
Nova Science Publishers
Año: 2013; p. 65 - 92
MicroRNAs (miRNAs) are short, non-coding RNAs that down-regulate gene expression post-transcriptionally by binding to the mRNA of their target genes. The importance of miRNAs in key biological processes such as development, cell proliferation, cell differentiation and metabolism has been widely documented since their discovery. To date, more than 25,000 mature miRNAs have been reported in 193 species of animals and plants (miRBase, release 19, Parasites face different environments during their complex life cycles and their ability to respond to environmental and developmental signals may require miRNA-mediated networking and fine-tuning of gene expression. Some protozoan and helminth parasites have shown peculiarities in their small-RNA machinery. For example, the small RNA-generating machinery of the apicomplexan parasite Toxoplasma gondii is phylogenetically and functionally related to that of plants and fungi. Among protozoan parasites, miRNAs have been reported in Giardia lamblia, Trichomonas vaginalis, Trichomonas foetus, Pentatrichomonas hominis, Trypanosoma brucei, Entameoba histolytica, Neospora caninum and Toxoplasma gondii. Most of the protozoan miRNAs do not share significant homology to any of the known miRNAs of plants and metazoans. Some interesting roles such as silencing of variant surface proteins have been proposed for a number of miRNAs in G. lamblia. However, in other unicellular parasites such as Trypanosoma cruzi and Plasmodium falciparum no miRNAs or small RNA machinery components have been identified. Among helminth parasites, miRNA identification and expression profile analyses have been performed by a combination of bioinformatic and experimental approaches. So far, miRNAs have been reported in the nematodes Angiostrongylus cantonensis, Brugia pahangi, Brugia malayi, Haemonchus contortus, Ascaris suum and Trichinella spiralis; the trematodes Fasciola hepatica, Fasciola gigantica, Schistosoma mansoni, Schistosoma japonicum, Clonorchis sinensis and Orientobilharzia turkestanicum and the cestodes Echinococcus granulosus, Echinococcus multilocularis and Taenia saginata. Conserved as well as novel miRNAs have been reported, some of them are abundantly expressed and display developmental regulation, suggesting important roles in several helminth parasite species. miRNA targets have been bioinformatically predicted in parasitic protozoa and helminths but only a small number of protozoan miRNAs has been experimentally validated. Unraveling miRNA roles in parasite biology and host interaction remains a challenge. For this end, bioinformatic strategies adapted to each phylum together with experimental strategies such as miRNA silencing and/or overexpression should be set up. The knowledge of miRNA roles in parasite development and survival in their hosts will in turn provide new control and intervention strategies against the worldwide distributed and mostly neglected diseases they produce.