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: 7.75). 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
 · 
102 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The eye has become an excellent target for gene therapy, and gene augmentation therapy of inherited retinal disorders has made major progress in recent years. Nevertheless, a recent study indicated that gene augmentation intervention might not stop the progression of retinal degeneration in patients. In addition, for many genes, viral-mediated gene augmentation is currently not feasible due to gene size and limited packaging capacity of viral vectors as well as expression of various heterogeneous isoforms of the target gene. Thus, alternative gene-based strategies to stop or delay the retinal degeneration are necessary. This review focuses on an alternative pharmacologic treatment strategy based on the usage of translational read-through inducing drugs (TRIDs) such as PTC124, aminoglycoside antibiotics, and designer aminoglycosides for overreading in-frame nonsense mutations. This strategy has emerged as an option for up to 30-50% of all cases of recessive hereditary retinal dystrophies. In-frame nonsense mutations are single-nucleotide alterations within the gene coding sequence resulting in a premature stop codon. Consequently, translation of such mutated genes leads to the synthesis of truncated proteins, which are unable to fulfill their physiologic functions. In this context, application of TRIDs facilitates the recoding of the premature termination codon into a sense codon, thus restoring syntheses of full-length proteins. So far, clinical trials for non-ocular diseases have been initiated for diverse TRIDs. Although the clinical outcome is not analyzed in detail, an excellent safety profile, namely for PTC124, was clearly demonstrated. Moreover, recent data demonstrated sustained read-through efficacies of nonsense mutations causing retinal degeneration, as manifested in the human Usher syndrome. In addition, a strong retinal biocompatibility for PTC124 and designer aminoglycosides has been demonstrated. In conclusion, recent progress emphasizes the potential of TRIDs as an alternative pharmacologic treatment strategy for treating nonsense mutation-based retinal disorders.
    Visual Neuroscience 06/2014; · 1.68 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Harlequin ichthyosis (HI) is the most severe and devastating form of the autosomal recessive congenital ichthyoses (ARCIs). Mutations in the ABCA12 gene result in disruption of intercellular lipid deposition in the stratum corneum and a major skin barrier defect. Patients present at birth, often premature, with cutaneous thick, yellow, hyperkeratotic plates with deep erythematous fissures, causing a typical facial appearance. Harlequin ichthyosis has often been considered to be fatal, and management tends to be palliative, but follow-up of 45 affected infants has shown that with good neonatal care and early introduction of oral retinoids, survival rates are improving. Because ABCA12 mutations have been identified, known carriers are able to undergo preventative preimplantation and prenatal genetic testing. Experimental studies have shown recovery of lipid secretion in lamellar granules using corrective gene therapy. Further research is needed to develop alternative therapies to retinoids in HI.
    Pediatric Dermatology 06/2014; · 1.52 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Negamycin is a natural product with broad-spectrum antibacterial activity and efficacy in animal models of infection. Although its precise mechanism of action has yet to be delineated, negamycin inhibits cellular protein synthesis and causes cell death. Here, we show that single point mutations within 16S rRNA that confer resistance to negamycin are in close proximity of the tetracycline binding site within helix 34 of the small subunit head domain. As expected from its direct interaction with this region of the ribosome, negamycin was shown to displace tetracycline. However, in contrast to tetracycline-class antibiotics, which serve to prevent cognate tRNA from entering the translating ribosome, single-molecule fluorescence resonance energy transfer investigations revealed that negamycin specifically stabilizes near-cognate ternary complexes within the A site during the normally transient initial selection process to promote miscoding. The crystal structure of the 70S ribosome in complex with negamycin, determined at 3.1 Å resolution, sheds light on this finding by showing that negamycin occupies a site that partially overlaps that of tetracycline-class antibiotics. Collectively, these data suggest that the small subunit head domain contributes to the decoding mechanism and that small-molecule binding to this domain may either prevent or promote tRNA entry by altering the initial selection mechanism after codon recognition and before GTPase activation.
    Proceedings of the National Academy of Sciences 11/2014; · 9.81 Impact Factor