title: Base pairing between hepatitis C virus RNA and microRNA 122 3' of its seed sequence is essential for genome stabilization and production of infectious virus.
abstract: MicroRNA 122 (miR-122) facilitates hepatitis C virus (HCV) replication by recruiting an RNA-induced silencing complex (RISC)-like complex containing argonaute 2 (Ago2) to the 5' end of the HCV genome, thereby stabilizing the viral RNA. This requires base pairing between the miR-122 "seed sequence" (nucleotides [nt] 2 to 8) and two sequences near the 5' end of the HCV RNA: S1 (nt 22 to 28) and S2 (nt 38 to 43). However, recent reports suggest that additional base pair interactions occur between HCV RNA and miR-122. We searched 606 sequences from a public database (genotypes 1 to 6) and identified two conserved, putatively single-stranded RNA segments, upstream of S1 (nt 2 and 3) and S2 (nt 30 to 34), with potential for base pairing to miR-122 (nt 15 and 16 and nt 13 to 16, respectively). Mutagenesis and genetic complementation experiments confirmed that HCV nt 2 and 3 pair with nt 15 and 16 of miR-122 bound to S1, while HCV nt 30 to 33 pair with nt 13 to 16 of miR-122 at S2. In genotype 1 and 6 HCV, nt 4 also base pairs with nt 14 of miR-122. These 3' supplementary base pair interactions of miR-122 are functionally important and are required for Ago2 recruitment to HCV RNA by miR-122, miR-122-mediated stabilization of HCV RNA, and production of infectious virus. However, while complementary mutations at HCV nt 30 and 31 efficiently rescued the activity of a 15C,16C miR-122 mutant targeting S2, similar mutations at nt 2 and 3 failed to rescue Ago2 recruitment at S1. These data add to the current understanding of miR-122 interactions with HCV RNA but indicate that base pairing between miR-122 and the 5' 43 nt of the HCV genome is more complex than suggested by existing models.
authors.affiliation: Division of Infectious Diseases, Department of Medicine, Inflammatory Diseases Institute and Lineberger Comprehensive Cancer Center, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Shimakami
authors.forename: Daisuke
authors.initials: D
authors.lastname: Yamane
authors.forename: Christoph
authors.initials: C
authors.lastname: Welsch
authors.forename: Lucinda
authors.initials: L
authors.lastname: Hensley
authors.forename: Rohit K
authors.initials: RK
authors.lastname: Jangra
authors.forename: Stanley M
authors.initials: SM
authors.lastname: Lemon
mesh_terms: D020029:Base Pairing; D001483:Base Sequence; D005816:Genetic Complementation Test; D042822:Genomic Instability; D016174:Hepacivirus / Q000235:genetics / Q000502:physiology*; D006801:Humans; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism*; D014779:Virus Replication
chemical_list: C531907:MIRN122 microRNA, human; D035683:MicroRNAs; D012367:RNA, Viral