[RNA interference: from origins to a novel tool for gene silencing].

RNA interference (RNAi) is a conserved biological mechanism triggered by double-stranded RNA from exogenous (small interfering RNA, siRNA) or endogenous origin (microRNAs, miRNA) that inhibits gene expression at transcriptional level. First discovered as an ancient anti-viral response, RNAi is now recognized as a natural regulatory mechanism for silencing gene expression in eukaryotes and as a powerful tool for investigating gene function. Over the last seven years, RNAi has become a valuable and standardized tool to silence gene expression in almost every scientific research field. This review describes the RNAi as a biological response and as a research tool for silencing gene expression, focusing on primary information required when the RNAi is applying for first time at a laboratory. It provides a basic guide to promote RNAi advantages and a list of available web tools for RNAi application in research field at a laboratory. Information about RNAi-based therapeutics development is included.