A conserved biological response to double-stranded RNA, known variously as RNA interference (RNAi) or post-transcriptional gene silencing, mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes. RNAi has been... mehr

The discovery of RNA interference (RNAi) may well be one of the transforming events in biology in the past decade. RNAi can result in gene silencing or even in the expulsion of sequences from the genome. Harnessed as an experimental tool, RNAi has revolutionized approaches to decoding gene... mehr

Our understanding of RNA interference has been enhanced by new data concerning RNase III molecules. The role of Dicer has previously been established in RNAi as the originator of 22-mers characteristic of silencing phenomena. Recently, a related RNAse III enzyme, Drosha, has surfaced as another... mehr

Senescence naturally limits the proliferation of mammalian cells in culture,possibly by shortening the telomere regions at the ends of chromosomes duringcell division. In support of this idea, introducing TERT,the catalytic subunit of telomerase — the enzyme that maintains chromosomeends —... mehr

Silencing gene expression by RNA interference (RNAi) has become a daily activity for mammalian cell biologists. Those who often use this approach have come to appreciate its occasional frustrations and potential limitations. A pair of recent papers in Cell provides rules for designing short... mehr

IN mammalian cells, DNA damage increases the levels of the nuclear tumour-suppressor p53, resulting in elevated synthesis of p21, an inhibitor of cyclin-dependent kinases (CDK)1Â6. p21 may also directly block DNA replication by inhibiting the proliferating-cell nuclear antigen (PCNA)7, an... mehr

RNA interference (RNAi) is the mechanism through which double-strandedRNAs silence cognate genes. In plants, this canoccur at both the transcriptional and the post-transcriptional levels; however, in animals, only post-transcriptional RNAi has beenreported to date. In both plants and animals,... mehr

DNA methylation has important functions in stable, transcriptional gene silencing, immobilization of transposable elements and genome organization. In Arabidopsis, DNA methylation can be induced by double-stranded RNA through the RNA interference (RNAi) pathway, a response known as RNA-directed... mehr

Mature microRNAs (miRNAs) are generated via a two-step processing pathway to yield ∼22-nucleotide small RNAs that regulate gene expression at the post-transcriptional level. Initial cleavage is catalysed by Drosha, a nuclease of the RNase III family, which acts on primary miRNA transcripts... mehr

RNA interference is a powerful method for suppressing gene expression in mammalian cells. Stable knock-down can be achieved by continuous expression of synthetic short hairpin RNAs, typically from RNA polymerase III promoters. But primary microRNA transcripts, which are endogenous triggers of RNA... mehr