Nucleic Acids Research Advance Access published online on October 6, 2009
Nucleic Acids Research, doi:10.1093/nar/gkp812
Molecular Biology |
Expanded RNA-binding activities of mammalian Argonaute 2
1Department of Medicine, 2Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA and 3Department of Microbiology and Immunology, Diabetes Center, University of California, San Francisco, CA 94122, USA
*To whom correspondence should be addressed. Tel: +1 215 573 6639; Fax: +1 215 573 7599; Email: kiriakim{at}uphs.upenn.edu
Received April 28, 2009. Revised September 14, 2009. Accepted September 15, 2009.
Mammalian Argonaute 2 (Ago2) protein associates with microRNAs (miRNAs) or small interfering RNAs (siRNAs) forming RNA-induced silencing complexes (RISCs/miRNPs). In the present work, we characterize the RNA-binding and nucleolytic activity of recombinant mouse Ago2. Our studies show that recombinant mouse Ago2 binds efficiently to miRNAs forming active RISC. Surprisingly, we find that recombinant mouse Ago2 forms active RISC using pre-miRNAs or long unstructured single stranded RNAs as guides. Furthermore, we demonstrate that, in vivo, endogenous human Ago2 binds directly to pre-miRNAs independently of Dicer, and that Ago2:pre-miRNA complexes are found both in the cytoplasm and in the nucleus of human cells.