Article

Pharmaceutical therapies to recode nonsense mutations in inherited diseases.

Department of Molecular Genetics, Microbiology, and Immunology, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway, NJ, United States.
Pharmacology [?] Therapeutics (Impact Factor: 7.79). 07/2012; 136(2):227-66. DOI: 10.1016/j.pharmthera.2012.07.007
Source: PubMed

ABSTRACT Nonsense codons, generated from nonsense mutations or frameshifts, contribute significantly to the spectrum of inherited human diseases such as cystic fibrosis, Duchenne muscular dystrophy, hemophilia, spinal muscular atrophy, and many forms of cancer. The presence of a mutant nonsense codon results in premature termination to preclude the synthesis of a full-length protein and leads to aberrations in gene expression. Suppression therapy to recode a premature termination codon with an amino acid allowing readthrough to rescue the production of a full-length protein presents a promising strategy for treatment of patients suffering from debilitating nonsense-mediated disorders. Suppression therapy using aminoglycosides to promote readthrough in vitro have been known since the sixties. Recent progress in the field of recoding via pharmaceuticals has led to the continuous discovery and development of several pharmacological agents with nonsense suppression activities. Here, we review the mechanisms that are involved in discriminating normal versus premature termination codons, the factors involved in readthrough efficiency, the epidemiology of several well-known nonsense-mediated diseases, and the various pharmacological agents (aminoglycoside and non-aminoglycoside compounds) that are currently being employed in nonsense suppression therapy studies. We also discuss how these therapeutic agents can be used to regulate gene expression for gene therapy applications.

0 Bookmarks
 · 
88 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Cystic fibrosis (CF) is an autosomal recessive disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene, which encodes an epithelial anion channel. Since the identification of the disease in 1938 and up until 2012, CF patients have been treated exclusively with medications aimed at bettering their respiratory, digestive, inflammatory and infectious symptoms. The identification of the CFTR gene in 1989 gave hopes of rapidly finding a cure for the disease, for which over 1,950 mutations have been identified. Since 2012, recent approaches have enabled the identification of small molecules targeting either the CFTR protein directly or its key processing steps, giving rise to novel promising therapeutic tools. This review presents the current CFTR mutation classifications according to their clinical consequences and to their effect on the structure and function of the CFTR channel. How these classifications are essential in the establishment of mutation-targeted therapeutic strategies is then discussed. The future of CFTR-targeted treatment lies in combinatory therapies that will enable CF patients to receive a customized treatment.
    The international journal of biochemistry & cell biology 01/2014; · 4.89 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: About 12% of human genetic disorders involve premature termination codons (PTCs). Aminoglycoside antibiotics have been proposed for restoring full-length proteins by readthrough of PTC. To assess the efficiency of readthrough, we selected homozygous and compound heterozygous skin fibroblasts from xeroderma pigmentosum (XP) patients with different PTCs in the XPC DNA repair gene. XP patients have a nucleotide excision repair defect and a 10,000-fold increased risk of UV-induced skin cancer. In six of eight PTC-containing XP-C cells, treatment with Geneticin and gentamicin resulted in (i) stabilized XPC-mRNA, which would have been degraded by nonsense-mediated decay; (ii) increased expression of XPC protein that localized to UV-damaged sites; (iii) recruitment of XPB and XPD proteins to UV DNA damage sites; and (iv) increased repair of 6-4 photoproducts and cyclobutane pyrimidine dimers. Expression of PTC in a transfected vector revealed that readthrough depends on the PTC sequence and its location within the gene. This sensitive DNA repair assay system demonstrates the complexity of response to PTC readthrough inducers. The efficiency of aminoglycoside-mediated readthrough depends on the type and copy number of PTC, the downstream 4+ nucleotide, and the location within the exon. Treatment with small-molecule nonaminoglycoside compounds (PTC124, BZ16, or RTC14) resulted in similarly increased XPC mRNA expression and photoproduct removal with less toxicity than with the aminoglycosides. Characterizing PTC structure and parameters governing effective PTC readthrough may provide a unique prophylactic therapy for skin cancer prevention in XP-C patients.
    Proceedings of the National Academy of Sciences 11/2013; · 9.81 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Kabuki syndrome is a multiple congenital anomalies syndrome characterized by characteristic facial features and varying degrees of mental retardation, caused by mutations in KMT2D/MLL2 and KDM6A/UTX genes. In this study we performed a mutational screening on 303 Kabuki patients by direct sequencing, MLPA, and qPCR identifying 133 KMT2D, 62 never described before, and 4 KDM6A mutations, three of them are novel. We found that a number of KMT2D truncating mutations result in mRNA degradation through the nonsense-mediated mRNA decay, contributing to protein haploinsufficiency. Furthermore we demonstrated that the reduction of KMT2D protein level in patients' lymphoblastoid and skin fibroblast cell lines carrying KMT2D truncating mutations affects the expression levels of known KMT2D target genes. Finally we hypothesized that the Kabuki syndrome patients may benefit from a readthrough therapy to restore physiological levels of KMT2D and KDM6A proteins. To assess this we performed a proof-of-principle study on 14 KMT2D and 2 KDM6A nonsense mutations using specific compounds that mediate translational readthrough and thereby stimulate the re-expression of full-length functional proteins. Our experimental data showed that both, KMT2D and KDM6A nonsense mutations, displayed high levels of readthrough in response to gentamicin treatment, paving the way to further studies aimed at eventually treating some Kabuki patients with readthrough inducers. This article is protected by copyright. All rights reserved.
    Human Mutation 03/2014; · 5.21 Impact Factor