Display Settings:

Format

Send to:

Choose Destination
We are sorry, but NCBI web applications do not support your browser and may not function properly. More information
Genes Dev. 2005 Dec 15;19(24):2979-90.

A human, ATP-independent, RISC assembly machine fueled by pre-miRNA.

Author information

  • 1Department of Pathology, Division of Neuropathology, University of Pennsylvania School of Medicine, Philadelphia, 19104, USA.

Abstract

RNA interference (RNAi) is mediated by RNA-induced silencing complexes (RISCs), which are guided by microRNAs (miRNAs) or short interfering RNAs (siRNAs) to cognate RNA targets. In humans, the catalytic engine of RISC is a ribonucleoprotein formed by the Argonaute2 (Ago2) protein and either miRNA (miRNP) or siRNA (siRNP). The Dicer nuclease produces mature miRNAs and siRNAs from pre-miRNAs and double-stranded RNA (dsRNA), respectively, and associates with Ago2. Here, we studied the assembly of human RISC by presenting pre-miRNA to immunopurified complexes that contain Ago2, Dicer, and TRBP. Mature miRNAs were produced in an ATP-independent manner and guided specific cleavage of cognate RNA targets in a pattern that is typical of RISC. This de novo formed RISC activity dissociated from Dicer. The asymmetry of the RISC loading process was fully recapitulated in this system, which, however, could not efficiently assemble RISC from siRNA duplexes. Our findings demonstrate that, in humans, a miRNA loading complex (miRLC) is formed by Ago2 and Dicer prior to their encounter with pre-miRNA. We suggest that the miRLC couples the processing of the pre-miRNA substrate to the unwinding of the product and that after loading of the mature miRNA to Ago2, the miRLC disassembles and the miRNP is released.

PMID:
16357216
[PubMed - indexed for MEDLINE]
PMCID:
PMC1315402
Free PMC Article

Images from this publication.See all images (8)Free text

Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Figure 6.
Figure 7.
Figure 8.
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire Icon for PubMed Central
    Loading ...
    Write to the Help Desk