Arginine-rich cell-penetrating peptide dramatically enhances AMO-mediated ATM aberrant splicing correction and enables delivery to brain and cerebellum

• Published in: Human molecular genetics 2011-08, Vol.20 (16), p.3151-3160
• Main Authors: Du, Liutao, Kayali, Refik, Bertoni, Carmen, Fike, Francesca, Hu, Hailiang, Iversen, Patrick L., Gatti, Richard A.
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Arginine - chemistry; Ataxia Telangiectasia - enzymology; Ataxia Telangiectasia - pathology; Ataxia Telangiectasia Mutated Proteins; Biological and medical sciences; Cell Cycle Proteins - genetics; Cell physiology; Cell transformation and carcinogenesis. Action of oncogenes and antioncogenes; Cell-Penetrating Peptides - chemistry; Cell-Penetrating Peptides - pharmacology; Cerebellum - drug effects; Cerebellum - metabolism; DNA-Binding Proteins - genetics; Fluorescein-5-isothiocyanate - metabolism; Fundamental and applied biological sciences. Psychology; Gene Transfer Techniques; Genetics of eukaryotes. Biological and molecular evolution; Mice; Molecular and cellular biology; Molecular Sequence Data; Oligonucleotides, Antisense - pharmacology; Protein Transport - drug effects; Protein-Serine-Threonine Kinases - genetics; Purkinje Cells - drug effects; Purkinje Cells - metabolism; Radiation Tolerance - drug effects; RNA Splicing - drug effects; RNA Splicing - genetics; Tumor Suppressor Proteins - genetics
• ISSN: 0964-6906; 1460-2083
• DOI: 10.1093/hmg/ddr217

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)2XB, 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)2XB-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)2XB-AMOs in A-T and other neurogenetic disorders.