Targeting genes in living mammals by RNA interference

More than a decade has passed since the discovery of RNA interference (RNAi), an eukaryotic sequence-specific degradation of mRNA induced by complementary double-stranded RNA (dsRNA). RNAi became a common tool for controlled down-regulation of gene expression in cultured cells, as well as in various model organisms. This review summarizes RNAi-based tools for silencing genes in living mammals, which include: (i) transgenic RNAi strategies, where RNAi is triggered by a transgene transmitted through the germline and (ii) approaches, where an RNAi trigger is delivered into an adult animal.