학술논문
Capitalizing on the heterogeneous effects of CFTR nonsense and frameshift variants to inform therapeutic strategy for cystic fibrosis.
Document Type
Article
Author
Sharma, Neeraj; Evans, Taylor A.; Pellicore, Matthew J.; Davis, Emily; Aksit, Melis A.; McCague, Allison F.; Joynt, Anya T.; Lu, Zhongzhu; Han, Sangwoo T.; Anzmann, Arianna F.; Lam, Anh-Thu N.; Thaxton, Abigail; West, Natalie; Merlo, Christian; Gottschalk, Laura B.; Raraigh, Karen S.; Sosnay, Patrick R.; Cotton, Calvin U.; Cutting, Garry R.
Source
Subject
*CYSTIC fibrosis transmembrane conductance regulator
*CYSTIC fibrosis treatment
*GENETIC code
*FRAMESHIFT mutation
*MESSENGER RNA
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Language
ISSN
1553-7390
Abstract
CFTR modulators have revolutionized the treatment of individuals with cystic fibrosis (CF) by improving the function of existing protein. Unfortunately, almost half of the disease-causing variants in CFTR are predicted to introduce premature termination codons (PTC) thereby causing absence of full-length CFTR protein. We hypothesized that a subset of nonsense and frameshift variants in CFTR allow expression of truncated protein that might respond to FDA-approved CFTR modulators. To address this concept, we selected 26 PTC-generating variants from four regions of CFTR and determined their consequences on CFTR mRNA, protein and function using intron-containing minigenes expressed in 3 cell lines (HEK293, MDCK and CFBE41o-) and patient-derived conditionally reprogrammed primary nasal epithelial cells. The PTC-generating variants fell into five groups based on RNA and protein effects. Group A (reduced mRNA, immature (core glycosylated) protein, function <1% (n = 5)) and Group B (normal mRNA, immature protein, function <1% (n = 10)) variants were unresponsive to modulator treatment. However, Group C (normal mRNA, mature (fully glycosylated) protein, function >1% (n = 5)), Group D (reduced mRNA, mature protein, function >1% (n = 5)) and Group E (aberrant RNA splicing, mature protein, function > 1% (n = 1)) variants responded to modulators. Increasing mRNA level by inhibition of NMD led to a significant amplification of modulator effect upon a Group D variant while response of a Group A variant was unaltered. Our work shows that PTC-generating variants should not be generalized as genetic ‘nulls’ as some may allow generation of protein that can be targeted to achieve clinical benefit. [ABSTRACT FROM AUTHOR]