title: RNA-mediated degradation of microRNAs: A widespread viral strategy?
abstract: Regulation of small RNAs by other non-coding RNAs is a ubiquitous feature of gene regulatory systems that can be exploited by viruses. Examples of this have been described in 3 different herpesviruses, where viral non-coding RNAs bind to highly abundant cellular (miRNAs), mediating their degradation: miR-27 is targeted by both murine cytomegalovirus and herpesvirus saimiri, while the miR-17 family is targeted by human cytomegalovirus. We review what is known about RNA-mediated regulation of miRNA stability and propose 3 potential roles that viral non-coding RNAs might assume to initiate the destruction of a miRNA, acting as "recruiters," "localizers" or "exposers." Whereas the miRNAs (miR-17 and miR-27) appear to be ancient and pre-date the common ancestor of all mammalian herpesviruses, comparative analyses of herpesvirus genomes indicate that the 3 known viral regulators of miRNA each evolved independently, and much more recently. Noting that the anti-viral activity of miRNAs might be countered by a variety of mechanisms, we propose that (i) there has been continual turnover of these mechanisms during herpesvirus evolution, and (ii) there may be many other, as yet undescribed, anti-miRNA activities encoded by other herpesviruses and indeed by viruses from other families.
authors: a Institute of Immunology and Infection Research; School of Biological Sciences; University of Edinburgh ; Edinburgh , UK.
authors: Jana
authors: J
authors: McCaskill
authors: Pairoa
authors: P
authors: Praihirunkit
authors: Paul M
authors: PM
authors: Sharp
authors: Amy H
authors: AH
authors: Buck
mesh_terms: D000818:Animals; D006561:Herpes Simplex / Q000378:metabolism*; D018259:Herpesvirus 1, Human / Q000378:metabolism*; D006801:Humans; D035683:MicroRNAs / Q000378:metabolism*; D020871:RNA Stability; D012367:RNA, Viral / Q000378:metabolism*
chemical_list: D035683:MicroRNAs; D012367:RNA, Viral
keywords: IL-10; RNA degradation; RNAi; herpesvirus; miRNA response element; microRNA; microRNA turnover; viral evolution