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Functional Anatomy of a dsRNA Trigger

2000; Elsevier BV; Volume: 6; Issue: 5 Linguagem: Inglês

10.1016/s1097-2765(00)00106-4

1097-4164

Susan Parrish, Jamie Fleenor, Siqun Xu, Craig C. Mello, Andrew Fire,

RNA and protein synthesis mechanisms

In RNA-mediated interference (RNAi), externally provided mixtures of sense and antisense RNA trigger concerted degradation of homologous cellular RNAs. We show that RNAi requires duplex formation between the two trigger strands, that the duplex must include a region of identity between trigger and target RNAs, and that duplexes as short as 26 bp can trigger RNAi. Consistent with in vitro observations, a fraction of input dsRNA is converted in vivo to short segments of ∼25 nt. Interference assays with modified dsRNAs indicate precise chemical requirements for both bases and backbone of the RNA trigger. Strikingly, certain modifications are well tolerated on the sense, but not the antisense, strand, indicating that the two trigger strands have distinct roles in the interference process.