oxadiazoles and Genetic-Diseases--Inborn

According to previous reports, nearly one in 10 genetic diseases are caused by nonsense mutations around the world. Nonsense mutations lead to premature transcription terminations in cells, which in turn generate non-functional, truncated proteins. In recent years, read-through drugs are playing increasing prominent roles in the researches related to genetic diseases caused by nonsense mutations. However, due to the fact that the mechanisms lying behind translation termination still remain to be elucidated, the mechanistic research and clinical application of read-through drugs are facing new challenges. This review mainly discusses about the pathogenesis of genetic diseases caused by nonsense mutations, and then introduces the current clinical application of read-through drugs. Finally, we display some problems that remain to be solved and propose some possible coping strategies.

Topics: Aminoglycosides; Codon, Nonsense; Cystic Fibrosis; Genetic Diseases, Inborn; Humans; Muscular Dystrophy, Duchenne; Oxadiazoles

An estimated one-third of genetic disorders are the result of mutations that generate premature termination codons (PTCs) within protein coding genes. These disorders are phenotypically diverse and consist of diseases that affect both young and old individuals. Various small molecules have been identified that are capable of modulating the efficiency of translation termination, including select antibiotics of the aminoglycoside family and multiple novel synthetic molecules, including PTC124. Several of these agents have proved their effectiveness at promoting nonsense suppression in preclinical animal models, as well as in clinical trials. In addition, it has recently been shown that box H/ACA RNA-guided peudouridylation, when directed to modify PTCs, can also promote nonsense suppression. In this review, we summarize our current understanding of eukaryotic translation termination and discuss various methods for promoting the read-through of disease-causing PTCs, as well as the current obstacles that stand in the way of using the discussed agents broadly in clinical practice.

Topics: Aminoglycosides; Anti-Bacterial Agents; Clinical Trials as Topic; Codon, Nonsense; Genetic Diseases, Inborn; Humans; Mutation; Oxadiazoles; Peptide Chain Termination, Translational; Ribonucleoproteins, Small Nucleolar

Premature termination codons (PTCs) are a cause of numerous genetic disorders spanning diseases that affect children and adults, and are produced by base pair substitutions that create abnormal stop codons within the open reading frame. Several ribosome-binding drugs, including select aminoglycosides and synthetic novel small molecules, induce 'translational readthrough' of PTCs, restoring full-length functional protein in a number of preclinical and clinical settings. In this review, we examine the mechanistic underpinnings of PTC suppression, including the nature of the interactions between agents that suppress PTCs and the eukaryotic ribosome regulation of transcript levels in eukaryotic cells, and the importance of the mRNA context in suppression of PTCs. We also examine results from proof-of-concept studies in preclinical model systems and clinical trials (with a focus on PTC124). Several of the published studies in cystic fibrosis have reported improvements in cystic fibrosis transmembrane conductance regulator (CFTR) biomarkers during short-term evaluation, including topical and systemic aminoglycoside treatment, and oral dosing with PTC124. These results, coupled with our improved understanding of how translation termination is regulated at PTCs, will help guide future directions of research involving this innovative treatment strategy for genetic diseases.

Topics: Aminoglycosides; Animals; Clinical Trials as Topic; Codon, Nonsense; Cystic Fibrosis; Genetic Diseases, Inborn; Humans; Muscular Dystrophies; Oxadiazoles; Protein Biosynthesis

Approximately one-third of alleles causing genetic diseases carry premature termination codons (PTCs), which lead to the production of truncated proteins. The past decade has seen considerable interest in therapeutic approaches aimed at readthrough of in-frame PTCs to enable synthesis of full-length proteins. However, attempts to readthrough PTCs in many diseases resulted in variable effects. Here, we focus on the efforts of such therapeutic approaches in cystic fibrosis and Duchenne muscular dystrophy and discuss the factors contributing to successful readthrough and how the nonsense-mediated mRNA decay (NMD) pathway regulates this response. A deeper understanding of the molecular basis for variable response to readthrough of PTCs is necessary so that appropriate therapies can be developed to treat many human genetic diseases caused by PTCs.

Topics: Alleles; Codon, Nonsense; Cystic Fibrosis; Genetic Diseases, Inborn; Humans; Models, Biological; Muscular Dystrophy, Duchenne; Oxadiazoles; RNA Stability; RNA, Messenger

Nonsense mutations promote premature translational termination and cause anywhere from 5-70% of the individual cases of most inherited diseases. Studies on nonsense-mediated cystic fibrosis have indicated that boosting specific protein synthesis from <1% to as little as 5% of normal levels may greatly reduce the severity or eliminate the principal manifestations of disease. To address the need for a drug capable of suppressing premature termination, we identified PTC124-a new chemical entity that selectively induces ribosomal readthrough of premature but not normal termination codons. PTC124 activity, optimized using nonsense-containing reporters, promoted dystrophin production in primary muscle cells from humans and mdx mice expressing dystrophin nonsense alleles, and rescued striated muscle function in mdx mice within 2-8 weeks of drug exposure. PTC124 was well tolerated in animals at plasma exposures substantially in excess of those required for nonsense suppression. The selectivity of PTC124 for premature termination codons, its well characterized activity profile, oral bioavailability and pharmacological properties indicate that this drug may have broad clinical potential for the treatment of a large group of genetic disorders with limited or no therapeutic options.

Topics: Alleles; Animals; Biological Availability; Codon, Nonsense; Dystrophin; Genetic Diseases, Inborn; Humans; Mice; Mice, Inbred mdx; Oxadiazoles; Phenotype; Protein Biosynthesis; RNA, Messenger; Substrate Specificity

Topics: Animals; Codon, Nonsense; Dystrophin; Genetic Diseases, Inborn; Humans; Oxadiazoles; Protein Biosynthesis; RNA, Messenger; Substrate Specificity