title: RNA duplexes with abasic substitutions are potent and allele-selective inhibitors of huntingtin and ataxin-3 expression.
abstract: Abasic substitutions within DNA or RNA are tools for evaluating the impact of absent nucleobases. Because of the importance of abasic sites in genetic damage, most research has involved DNA. Little information is available on the impact of abasic substitutions within RNA or on RNA interference (RNAi). Here, we examine the effect of abasic substitutions on RNAi and allele-selective gene silencing. Huntington's disease (HD) and Machado Joseph Disease (MJD) are severe neurological disorders that currently have no cure. HD and MJD are caused by an expansion of CAG repeats within one mRNA allele encoding huntingtin (HTT) and ataxin-3 (ATX-3) proteins. Agents that silence mutant HTT or ATX-3 expression would remove the cause of HD or MJD and provide an option for therapeutic development. We describe flexible syntheses for abasic substitutions and show that abasic RNA duplexes allele-selectively inhibit both mutant HTT and mutant ATX-3. Inhibition involves the RNAi protein argonaute 2, even though the abasic substitution disrupts the catalytic cleavage of RNA target by argonaute 2. Several different abasic duplexes achieve potent and selective inhibition, providing a broad platform for subsequent development. These findings introduce abasic substitutions as a tool for tailoring RNA duplexes for gene silencing.
authors.affiliation: Departments of Pharmacology and Biochemistry, UT Southwestern Medical Center, 6001 Forest Park Road, Dallas, TX 75390-9041, USA, Department of Chemistry and Institute for Life Sciences, University of Southampton, Highfield, Southampton, SO17 1BJ, UK and Alnylam Pharmaceuticals, 300 Third St., Cambridge, MA 02142, USA.
authors.forename: Jing
authors.initials: J
authors.lastname: Liu
authors.forename: Hannah
authors.initials: H
authors.lastname: Pendergraff
authors.forename: K Jayaprakash
authors.initials: KJ
authors.lastname: Narayanannair
authors.forename: Jeremy G
authors.initials: JG
authors.lastname: Lackey
authors.forename: Satya
authors.initials: S
authors.lastname: Kuchimanchi
authors.forename: Kallanthottathil G
authors.initials: KG
authors.lastname: Rajeev
authors.forename: Muthiah
authors.initials: M
authors.lastname: Manoharan
authors.forename: Jiaxin
authors.initials: J
authors.lastname: Hu
authors.forename: David R
authors.initials: DR
authors.lastname: Corey
mesh_terms: D000483:Alleles; D000067699:Ataxin-3; D020137:Base Pair Mismatch; D002460:Cell Line; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000235:genetics; D017827:Machado-Joseph Disease / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000138:chemical synthesis / Q000737:chemistry*; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism
chemical_list: C086055:HTT protein, human; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D034741:RNA, Small Interfering; D012097:Repressor Proteins; C092341:ATXN3 protein, human; D000067699:Ataxin-3