**Therapy for Cystic Fibrosis Caused by Nonsense Mutations**

Roberto Gambari, Giulia Breveglieri, Francesca Salvatori, Alessia Finotti and Monica Borgatti

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/61053

#### **Abstract**

Nonsense mutations cover about 10% of cystic fibrosis (CF) patients and generate premature termination codons (PTCs) leading to premature translational termination and causing the synthesis of truncated non-functional or partially functional CFTR (cystic fibrosis transmembrane conductance regulator) protein. The read-through approach is the suppression of translation terminations at PTCs and it has been developed as a therapeutic strategy to restore full-length protein using aminoglyco‐ side antibiotics or PTC124. Phenotypic consequences of PTCs can be exacerbated by the nonsense-mediated mRNA decay (NMD) pathway, which detects and degrades mRNA containing PTC. Therefore, modulation of NMD is also of interest as a potential target for suppression therapy. Not all PTCs are susceptible to the read-through treatment alone, especially where the nonsense mutations are combined with other CFTR mutations. For example, many CF patients present the highly frequent F508del CF mutation, causing an alteration of the cell membrane positioning of the CFTR channel. Pharmacological correctors that rescue the trafficking of F508del CFTR may overcome this defect. A combined administration of correctors/potentiators, readthrough molecules, and/or NMD inhibitors, depending on the genotype of the CF patients, could be the basis for the design of a personalized therapeutic approach.

**Keywords:** Cystic fibrosis, PTCs, read-through, NMD inhibitors, correctors, poten‐ tiators

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