title: Systematic identification of mRNAs recruited to argonaute 2 by specific microRNAs and corresponding changes in transcript abundance.
abstract: microRNAs (miRNAs) are small non-coding RNAs that regulate mRNA stability and translation through the action of the RNAi-induced silencing complex (RISC). Our current understanding of miRNA function is inferred largely from studies of the effects of miRNAs on steady-state mRNA levels and from seed match conservation and context in putative targets. Here we have taken a more direct approach to these issues by comprehensively assessing the miRNAs and mRNAs that are physically associated with Argonaute 2 (Ago2), which is a core RISC component. We transfected HEK293T cells with epitope-tagged Ago2, immunopurified Ago2 together with any associated miRNAs and mRNAs, and quantitatively determined the levels of these RNAs by microarray analyses. We found that Ago2 immunopurified samples contained a representative repertoire of the cell's miRNAs and a select subset of the cell's total mRNAs. Transfection of the miRNAs miR-1 and miR-124 caused significant changes in the association of scores of mRNAs with Ago2. The mRNAs whose association with Ago2 increased upon miRNA expression were much more likely to contain specific miRNA seed matches and to have their overall mRNA levels decrease in response to the miRNA transfection than expected by chance. Hundreds of mRNAs were recruited to Ago2 by each miRNA via seed sequences in 3'-untranslated regions and coding sequences and a few mRNAs appear to be targeted via seed sequences in 5'-untranslated regions. Microarray analysis of Ago2 immunopurified samples provides a simple, direct method for experimentally identifying the targets of miRNAs and for elucidating roles of miRNAs in cellular regulation.
authors.affiliation: Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: David G
authors.initials: DG
authors.lastname: Hendrickson
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Hogan
authors.forename: Daniel
authors.initials: D
authors.lastname: Herschlag
authors.forename: James E
authors.initials: JE
authors.lastname: Ferrell
authors.forename: Patrick O
authors.initials: PO
authors.lastname: Brown
mesh_terms: D020413:3' Untranslated Regions / Q000235:genetics; D020121:5' Untranslated Regions / Q000235:genetics; D000818:Animals; D060565:Argonaute Proteins; D002460:Cell Line; D029721:Drosophila Proteins / Q000235:genetics*; D005786:Gene Expression Regulation; D020868:Gene Silencing; D006801:Humans; D007668:Kidney; D007700:Kinetics; D035683:MicroRNAs / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D034743:RNA-Induced Silencing Complex / Q000235:genetics*; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; C433807:AGO2 protein, Drosophila; D060565:Argonaute Proteins; D029721:Drosophila Proteins; D035683:MicroRNAs; D012333:RNA, Messenger; D034743:RNA-Induced Silencing Complex