Why Only Some Cystic Fibrosis Patients Respond To Treatments That Prevent The Generation Of Truncated Proteins

Individuals with the genetic lung disorder cystic fibrosis (CF) lack any functional CFTR protein because their genes that encode this protein carry a mutation. One mutation (the W1282X mutation) that results in CF does so because it causes the cellular machinery that converts the initial product of a gene (mRNA) into a functional protein to prematurely stop making CFTR protein. Agents (such as gentamicin) that enable the protein-generating machinery to ignore such mutations have shown benefit in some, but not all, CF patients with the W1282X mutation. In a study that appears online in advance of publication in the March print issue of the Journal of Clinical Investigation, researchers from The Hebrew University of Jerusalem, Israel, describe a potential molecular explanation for the distinct responsiveness of patients with Cf to treatment with gentamicin.

Batsheva Kerem and colleagues found that CF patients with the W1282X mutation who responded to treatment with gentamicin expressed more nonsense CFTR mRNA than patients who did not respond to treatment. Further analysis showed that different cell lines from CF patients with the W1282X mutation had distinct abilities to destroy nonsense mRNA. Inhibiting the destruction of nonsense mRNA in these cell lines increased the amount of nonsense CFTR mRNA present, making them more susceptible to the ability of gentamicin to induce the production of functional CFTR protein. This study suggests that the ability of an individual's affected cells to destroy nonsense mRNA determines how responsive CF patients with the W1282X mutation are likely to be to treatment with gentamicin. Such observations might also extend to other genetic disorders in which mutations causing the cellular machinery to prematurely stop making protein have been identified, such as Duchenne muscular dystrophy.

TITLE: Nonsense-mediated mRNA decay affects nonsense transcript levels and governs response of cystic fibrosis patients to gentamicin

AUTHOR CONTACT:
Batsheva Kerem
The Hebrew University of Jerusalem, Jerusalem, Israel.

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JCI table of contents -- February 8, 2006

Contact: Karen Honey
Journal of Clinical Investigation