title: Phosphorodiamidate morpholino oligomers suppress mutant huntingtin expression and attenuate neurotoxicity.
abstract: Huntington's disease (HD) is a neurodegenerative disorder caused by a CAG trinucleotide repeat expansion in the huntingtin (HTT) gene. Disease pathogenesis derives, at least in part, from the long polyglutamine tract encoded by mutant HTT. Therefore, considerable effort has been dedicated to the development of therapeutic strategies that significantly reduce the expression of the mutant HTT protein. Antisense oligonucleotides (ASOs) targeted to the CAG repeat region of HTT transcripts have been of particular interest due to their potential capacity to discriminate between normal and mutant HTT transcripts. Here, we focus on phosphorodiamidate morpholino oligomers (PMOs), ASOs that are especially stable, highly soluble and non-toxic. We designed three PMOs to selectively target expanded CAG repeat tracts (CTG22, CTG25 and CTG28), and two PMOs to selectively target sequences flanking the HTT CAG repeat (HTTex1a and HTTex1b). In HD patient-derived fibroblasts with expanded alleles containing 44, 77 or 109 CAG repeats, HTTex1a and HTTex1b were effective in suppressing the expression of mutant and non-mutant transcripts. CTGn PMOs also suppressed HTT expression, with the extent of suppression and the specificity for mutant transcripts dependent on the length of the targeted CAG repeat and on the CTG repeat length and concentration of the PMO. PMO CTG25 reduced HTT-induced cytotoxicity in vitro and suppressed mutant HTT expression in vivo in the N171-82Q transgenic mouse model. Finally, CTG28 reduced mutant HTT expression and improved the phenotype of Hdh(Q7/Q150) knock-in HD mice. These data demonstrate the potential of PMOs as an approach to suppressing the expression of mutant HTT.
authors.affiliation: Division of Neurobiology, Department of Psychiatry and Behavioral Sciences.
authors.forename: Xin
authors.initials: X
authors.lastname: Sun
authors.affiliation: Division of Neurobiology, Department of Psychiatry and Behavioral Sciences.
authors.forename: Leonard O
authors.initials: LO
authors.lastname: Marque
authors.affiliation: Behavioral Neuroscience Laboratory, Department of Psychiatry and Behavioral Sciences.
authors.forename: Zachary
authors.initials: Z
authors.lastname: Cordner
authors.affiliation: Division of Neurobiology, Department of Psychiatry and Behavioral Sciences.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Pruitt
authors.affiliation: Division of Neurobiology, Department of Psychiatry and Behavioral Sciences.
authors.forename: Manik
authors.initials: M
authors.lastname: Bhat
authors.affiliation: Division of Neurobiology, Department of Psychiatry and Behavioral Sciences.
authors.forename: Pan P
authors.initials: PP
authors.lastname: Li
authors.affiliation: Division of Neurobiology, Department of Psychiatry and Behavioral Sciences.
authors.forename: Geetha
authors.initials: G
authors.lastname: Kannan
authors.affiliation: Behavioral Neuroscience Laboratory, Department of Psychiatry and Behavioral Sciences.
authors.forename: Ellen E
authors.initials: EE
authors.lastname: Ladenheim
authors.affiliation: Behavioral Neuroscience Laboratory, Department of Psychiatry and Behavioral Sciences.
authors.forename: Timothy H
authors.initials: TH
authors.lastname: Moran
authors.affiliation: Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Department of Neurology, and Program of Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA.
authors.forename: Russell L
authors.initials: RL
authors.lastname: Margolis
authors.affiliation: Division of Neurobiology, Department of Psychiatry and Behavioral Sciences, Program of Cellular and Molecular Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21287, USA drudnic1@jhmi.edu.
authors.forename: Dobrila D
authors.initials: DD
authors.lastname: Rudnicki
mesh_terms: D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D005347:Fibroblasts / Q000187:drug effects / Q000378:metabolism; D015870:Gene Expression; D055879:Gene Knock-In Techniques; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000235:genetics; D051379:Mice; D008822:Mice, Transgenic; D060172:Morpholinos / Q000737:chemistry / Q000494:pharmacology*; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D016376:Oligonucleotides, Antisense / Q000737:chemistry / Q000494:pharmacology*; D012333:RNA, Messenger / Q000378:metabolism; D019680:Trinucleotide Repeat Expansion
chemical_list: C086055:HTT protein, human; D000071058:Huntingtin Protein; D060172:Morpholinos; D009419:Nerve Tissue Proteins; D016376:Oligonucleotides, Antisense; D012333:RNA, Messenger