RNA Helicase A Interacts with RISC in Human Cells and Functions in RISC Loading

• DOI: 10.1016/j.molcel.2007.04.016
• Publication Date: 2007-05-25T12:54:55Z
• Authors: G. Brett Robb; Tariq M. Rana
• Keywords: RNA-induced silencing complex; Dicer; Argonaute; RNA Silencing; RNA Helicase A; Trans-acting siRNA

RNA interference is a conserved pathway of sequence-specific gene silencing that depends on small guide RNAs and the action of proteins assembled in the RNA-induced silencing complex (RISC). Minimally, the action of RISC requires the endonucleolytic slicer activity of Argonaute2 (Ago2) directed to RNA targets whose sequences are complementary to RISC-incorporated small RNA. To identify RISC components in human cells, we developed an affinity-purification strategy to isolate siRNA-programmed RISC. Here we report the identification of RNA helicase A (RHA) as a human RISC-associated factor. We show that RHA interacts in human cells with siRNA, Ago2, TRBP, and Dicer and functions in the RNAi pathway. In RHA-depleted cells, RNAi was reduced as a consequence of decreased intracellular concentration of active RISC assembled with the guide-strand RNA and Ago2. Our results identify RHA as a RISC component and demonstrate that RHA functions in RISC as an siRNA-loading factor.