Position-dependent function for a tandem microRNA miR-122-binding site located in the hepatitis C virus RNA genome.
MicroRNAs usually interact with 3' noncoding regions (3'NCRs) of target mRNAs leading to downregulation of mRNA expression. In contrast, liver-specific microRNA miR-122 interacts with the 5' end of the hepatitis C virus RNA genome, resulting in increased viral RNA abundance. We find that inserting the viral miR-122 binding site into the 3' noncoding region of a reporter mRNA leads to downregulation of mRNA expression, indicating that the location of the miR-122 binding site dictates its effect on gene regulation. Furthermore, we discovered an adjacent, second miR-122 binding site, separated from the first by a highly conserved 14-nucleotide sequence. Mutational analysis demonstrates that both miR-122 binding sites in a single viral genome are occupied by the microRNA and function cooperatively to regulate target gene expression. These findings set a paradigm for dual, position-dependent functions of tandem microRNA-binding sites. Targeting an oligomeric microRNA complex offers potential as an antiviral-intervention strategy.
Jopling
Catherine L
CL
Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA, UK; Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Schütz
Sylvia
S
Sarnow
Peter
P
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D001665:Binding Sites; D004252:DNA Mutational Analysis; D017930:Genes, Reporter; D016679:Genome, Viral; D016174:Hepacivirus / Q000235:genetics*; D035683:MicroRNAs / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D012367:RNA, Viral / Q000235:genetics* / Q000378:metabolism*
D020413:3' Untranslated Regions; D020121:5' Untranslated Regions; D035683:MicroRNAs; D012333:RNA, Messenger; D012367:RNA, Viral