title: Arginine-rich cell-penetrating peptide dramatically enhances AMO-mediated ATM aberrant splicing correction and enables delivery to brain and cerebellum.
abstract: Antisense morpholino oligonucleotides (AMOs) can reprogram pre-mRNA splicing by complementary binding to a target site and regulating splice site selection, thereby offering a potential therapeutic tool for genetic disorders. However, the application of this technology into a clinical scenario has been limited by the low correction efficiency in vivo and inability of AMOs to efficiently cross the blood brain barrier and target brain cells when applied to neurogenetic disorders such as ataxia-telangiecatasia (A-T). We previously used AMOs to correct subtypes of ATM splicing mutations in A-T cells; AMOs restored up to 20% of the ATM protein and corrected the A-T cellular phenotype. In this study, we demonstrate that an arginine-rich cell-penetrating peptide, (RXRRBR)(2)XB, dramatically improved ATM splicing correction efficiency when conjugated with AMOs, and almost fully corrected aberrant splicing. The restored ATM protein was close to normal levels in cells with homozygous splicing mutations, and a gene dose effect was observed in cells with heterozygous mutations. A significant amount of the ATM protein was still detected 21 days after a single 5 µm treatment. Systemic administration of an fluorescein isothiocyanate-labeled (RXRRBR)(2)XB-AMO in mice showed efficient uptake in the brain. Fluorescence was evident in Purkinje cells after a single intravenous injection of 60 mg/kg. Furthermore, multiple injections significantly increased uptake in all areas of the brain, notably in cerebellum and Purkinje cells, and showed no apparent signs of toxicity. Taken together, these results highlight the therapeutic potential of (RXRRBR)(2)XB-AMOs in A-T and other neurogenetic disorders.
authors.affiliation: Department of Pathology and Laboratory Medicine, The David Geffen School of Medicine at UCLA, Los Angeles, CA 90095-1732, USA. ldu@mednet.ucla.edu
authors.forename: Liutao
authors.initials: L
authors.lastname: Du
authors.forename: Refik
authors.initials: R
authors.lastname: Kayali
authors.forename: Carmen
authors.initials: C
authors.lastname: Bertoni
authors.forename: Francesca
authors.initials: F
authors.lastname: Fike
authors.forename: Hailiang
authors.initials: H
authors.lastname: Hu
authors.forename: Patrick L
authors.initials: PL
authors.lastname: Iversen
authors.forename: Richard A
authors.initials: RA
authors.lastname: Gatti
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000737:chemistry*; D001260:Ataxia Telangiectasia / Q000201:enzymology / Q000473:pathology; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000235:genetics*; D057846:Cell-Penetrating Peptides / Q000737:chemistry / Q000494:pharmacology*; D002531:Cerebellum / Q000187:drug effects / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics*; D016650:Fluorescein-5-isothiocyanate / Q000378:metabolism; D018014:Gene Transfer Techniques; D051379:Mice; D008969:Molecular Sequence Data; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D021381:Protein Transport / Q000187:drug effects; D011689:Purkinje Cells / Q000187:drug effects / Q000378:metabolism; D012326:RNA Splicing / Q000187:drug effects / Q000235:genetics*; D011836:Radiation Tolerance / Q000187:drug effects; D025521:Tumor Suppressor Proteins / Q000235:genetics*
chemical_list: D018797:Cell Cycle Proteins; D057846:Cell-Penetrating Peptides; D004268:DNA-Binding Proteins; D016376:Oligonucleotides, Antisense; D025521:Tumor Suppressor Proteins; D001120:Arginine; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases; D016650:Fluorescein-5-isothiocyanate