title: Single nucleotide seed modification restores in vivo tolerability of a toxic artificial miRNA sequence in the mouse brain.
abstract: Huntington's disease is a fatal neurodegenerative disease caused by polyglutamine-expansion in huntingtin (HTT). Recent work showed that gene silencing approaches, including RNA interference (RNAi), improve disease readouts in mice. To advance RNAi to the clinic, we designed miHDS1, with robust knockdown of human HTT and minimized silencing of unintended transcripts. In Rhesus macaque, AAV delivery of miHDS1 to the putamen reduced HTT expression with no adverse effects on neurological status including fine and gross motor skills, no immune activation and no induction of neuropathology out to 6 weeks post injection. Others showed safety of a different HTT-targeting RNAi in monkeys for 6 months. Application of miHDS1 to Huntington's patients requires further safety testing in normal rodents, despite the fact that it was optimized for humans. To satisfy this regulatory requirement, we evaluated normal mice after AAV.miHDS1 injection. In contrast to monkeys, neurological deficits occurred acutely in mice brain and was attributed to off-target silencing through interactions of miHDS1 with the 3'UTR of other transcripts. While we resolved miHDS1 toxicity in mouse brain and maintained miHDS1-silencing efficacy, these studies highlight that optimizing nucleic acid-based medicines for safety in humans presents challenges for safety testing in rodents or other distantly related species.
authors.affiliation: The Center for Cell and Molecular Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
authors.forename: Alex Mas
authors.initials: AM
authors.lastname: Monteys
authors.affiliation: Internal Medicine, University of Iowa, Iowa City, IA 52242, USA.
authors.forename: Ryan M
authors.initials: RM
authors.lastname: Spengler
authors.affiliation: Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR 97006, USA Department of Behavioral Neuroscience, Oregon Health Sciences University, Portland, OR 97239, USA.
authors.forename: Brett D
authors.initials: BD
authors.lastname: Dufour
authors.affiliation: Internal Medicine, University of Iowa, Iowa City, IA 52242, USA.
authors.forename: Matt S
authors.initials: MS
authors.lastname: Wilson
authors.affiliation: Internal Medicine, University of Iowa, Iowa City, IA 52242, USA.
authors.forename: Clayton K
authors.initials: CK
authors.lastname: Oakley
authors.affiliation: The Center for Cell and Molecular Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA.
authors.forename: Matt J
authors.initials: MJ
authors.lastname: Sowada
authors.affiliation: Division of Neuroscience, Oregon National Primate Research Center, Beaverton, OR 97006, USA Department of Behavioral Neuroscience, Oregon Health Sciences University, Portland, OR 97239, USA.
authors.forename: Jodi L
authors.initials: JL
authors.lastname: McBride
authors.affiliation: The Center for Cell and Molecular Medicine, The Children's Hospital of Philadelphia, Philadelphia, PA 19104, USA Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA davidsonbl@email.chop.edu.
authors.forename: Beverly L
authors.initials: BL
authors.lastname: Davidson
mesh_terms: D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D001927:Brain Diseases / Q000139:chemically induced; D002460:Cell Line; D057809:HEK293 Cells; D006801:Humans; D000071058:Huntingtin Protein; D008253:Macaca mulatta; D051379:Mice; D035683:MicroRNAs / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity*; D009419:Nerve Tissue Proteins / Q000235:genetics* / Q000378:metabolism; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D009711:Nucleotides; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism
chemical_list: C086055:HTT protein, human; C506812:Htt protein, mouse; D000071058:Huntingtin Protein; D035683:MicroRNAs; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D009711:Nucleotides; D012333:RNA, Messenger