ATP modulates siRNA interactions with an endogenous human Dicer complex.

Short interfering RNA (siRNA) binding by Dicer is important for RNA interference in Drosophila, but human Dicer (hDcr) has been reported to lack siRNA binding activity. We used native gel electrophoresis to characterize the siRNA-binding activity of endogenous hDcr-containing complexes in extracts from human cells. We identified a complex (D) that contains hDcr, as demonstrated by antibody supershift.

A Dicer-2-dependent 80s complex cleaves targeted mRNAs during RNAi in Drosophila.

We use native gel electrophoresis to characterize complexes that mediate RNA interference (RNAi) in Drosophila. Our data reveal three distinct complexes (R1, R2, and R3) that assemble on short interfering RNAs (siRNAs) in vitro. To form, all three complexes require Dicer-2 (Dcr-2), which directly contacts siRNAs in the ATP-independent R1 complex.

R2D2 leads the silencing trigger to mRNA's death star.

During RNA interference (RNAi), Dicer generates short interfering RNAs (siRNAs), which then guide target mRNA cleavage by the RISC complex. Now, Liu et al. identify R2D2, a Dicer-associated protein that is important for siRNA incorporation into RISC, thus linking the initiation and execution phases of RNAi.