Hsc70/Hsp90 Chaperone Machinery Mediates ATP-Dependent RISC Loading of Small RNA Duplexes

• Published in: Molecular cell Vol. 39; no. 2; pp. 292 - 299
• Main Authors: Iwasaki, Shintaro, Kobayashi, Maki, Yoda, Mayuko, Sakaguchi, Yuriko, Katsuma, Susumu, Suzuki, Tsutomu, Tomari, Yukihide
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 30.07.2010
• Subjects: Adenosine Triphosphate - metabolism; Animals; ATP; Drosophila melanogaster; Drosophila Proteins - genetics; Drosophila Proteins - metabolism; HSC70 Heat-Shock Proteins - genetics; HSC70 Heat-Shock Proteins - metabolism; HSP90 Heat-Shock Proteins - genetics; HSP90 Heat-Shock Proteins - metabolism; MicroRNAs - genetics; MicroRNAs - metabolism; PROTEINS; RNA; RNA, Double-Stranded - genetics; RNA, Double-Stranded - metabolism; RNA, Small Interfering - genetics; RNA, Small Interfering - metabolism; RNA-Induced Silencing Complex - genetics; RNA-Induced Silencing Complex - metabolism; RNA; PROTEINS
• ISSN: 1097-2765; 1097-4164
• DOI: 10.1016/j.molcel.2010.05.015

Small silencing RNAs—small interfering RNAs (siRNAs) or microRNAs (miRNAs)—direct posttranscriptional gene silencing of their mRNA targets as guides for the RNA-induced silencing complex (RISC). Both siRNAs and miRNAs are born double stranded. Surprisingly, loading these small RNA duplexes into Argonaute proteins, the core components of RISC, requires ATP, whereas separating the two small RNA strands within Argonaute does not. Here we show that the Hsc70/Hsp90 chaperone machinery is required to load small RNA duplexes into Argonaute proteins, but not for subsequent strand separation or target cleavage. We envision that the chaperone machinery uses ATP and mediates a conformational opening of Ago proteins so that they can receive bulky small RNA duplexes. Our data suggest that the chaperone machinery may serve as the driving force for the RISC assembly pathway. [Display omitted] ► Hsc70/Hsp90 machinery mediates ATP-dependent RISC loading of small RNA duplexes ► Hsc70/Hsp90 machinery is dispensable for duplex separation or target cleavage ► Hsc70-4 is an important factor for RISC loading in flies