RNA INTERFERENCE MEDIATING SMALL RNA MOLECULES

摘要

Abstract Double-stranded RNA (dsRNA) induces sequence-specific post-transcrip 5 tional gene silencing in many organisms by a process known as .RNA interference (RNAI). Using a Drosophila in vitro system, we demonstrate that 19-23 nt short RNA fragments are the sequence-specific mediators of RNAi. The short interfering RNAs (siRNAs) are generated by an RNase Ill like processing reaction from long dsRNA. Chemically synthesized siRNA 10 duplexes with overhanging 3' ends mediate efficient target RNA cleavage. in the lysate, and the cleavage site is located near the center of the region spanned by the guiding siRNA. Furthermore, we provide evidence that the direction of dsRNA processing determines whether sense or aptisense target RNA can be cleaved by the produced siRNP complex.