RNAi and miRNA pathways in birds

Abstract

RNA silencing denotes sequence-specific repression mediated by small RNAs. In vertebrates, there are two closely related pathways, which share several protein factors: RNA interference (RNAi) and microRNA (miRNA) pathway. The miRNA pathway regulates endogenous protein-coding gene expression and has been implicated in many biological processes. RNAi generally serves as a form of innate immunity targeting viruses and mobile elements. This text reviews miRNA and RNAi pathways in birds. Although the available literature on RNA silencing in birds is very limited, many features can be deduced from the genomic data in the public domain. miRNA, RNAi and other dsRNA-responding pathways in birds appear very much like those in mammals, important bird-specific features of RNA silencing pathways are yet to be identified. The miRNA pathway is likely the dominant small RNA pathway while the existence and functionality of endogenous RNAi remains unclear. Some variations may be present in the main bird antiviral interferon system.