title: siRNAs targeted to certain polyadenylation sites promote specific, RISC-independent degradation of messenger RNAs.
abstract: While most siRNAs induce sequence-specific target mRNA cleavage and degradation in a process mediated by Ago2/RNA-induced silencing complex (RISC), certain siRNAs have also been demonstrated to direct target RNA reduction through deadenylation and subsequent degradation of target transcripts in a process which involves Ago1/RISC and P-bodies. In the current study, we present data suggesting that a third class of siRNA exist, which are capable of promoting target RNA reduction that is independent of both Ago and RISC. These siRNAs bind the target messenger RNA at the polyA signal and are capable of redirecting a small amount of polyadenylation to downstream polyA sites when present, however, the majority of the activity appears to be due to inhibition of polyadenylation or deadenylation of the transcript, followed by exosomal degradation of the immature mRNA.
authors.affiliation: Department of Core Antisense Research, ISIS Pharmaceuticals, Inc. 2855 Gazelle Court, Carlsbad, CA 92010, USA. tvickers@isisph.com
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Vickers
authors.forename: Stanley T
authors.initials: ST
authors.lastname: Crooke
mesh_terms: D000818:Animals; D060565:Argonaute Proteins / Q000235:genetics / Q000378:metabolism; D005095:Exoribonucleases / Q000378:metabolism; D051379:Mice; D026723:Polyadenylation; D012333:RNA, Messenger / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism; D034743:RNA-Induced Silencing Complex / Q000378:metabolism; D019948:Receptors, Interleukin-4 / Q000235:genetics / Q000378:metabolism
chemical_list: C526735:Ago2 protein, mouse; D060565:Argonaute Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D034743:RNA-Induced Silencing Complex; D019948:Receptors, Interleukin-4; D005095:Exoribonucleases