Small-molecule eRF3a degraders rescue CFTR nonsense mutations by promoting premature termination codon readthrough

Area of Science:

• Cell Biology
• Genetic Diseases
• Drug Discovery

Background:

• Most cystic fibrosis (CF) patients benefit from CF transmembrane regulator (CFTR) modulator therapy.
• A subset of CF patients with premature termination codons (PTCs) or rare CFTR variants lack effective treatments.
• Primary airway epithelial cells accurately predict modulator response but are scarce for rare variants.

Purpose of the Study:

• To develop and validate immortalized airway epithelial cell lines for studying rare CFTR variants.
• To assess the utility of these cell lines in predicting CFTR modulator efficacy.
• To explore novel therapeutic strategies for CFTR nonsense mutations.

Main Methods:

• Overexpression of mouse Bmi-1 and human TERT (hTERT) to create immortalized airway epithelial cell lines.
• Characterization of cell line morphology and ion transport function.
• Testing response to CFTR modulators and novel therapeutic agents (e.g., Cereblon E3 ligase modulators).

Main Results:

• Successfully generated 8 airway epithelial cell lines (2 non-CF, 6 CF), including 3 with homozygous W1282X PTC.
• Bmi-1/hTERT cell lines replicated primary cell characteristics and accurately predicted F508del-CFTR modulator responses.
• Cereblon modulators partially restored W1282X-CFTR function and, with G418, significantly rescued G542X-CFTR function.

Conclusions:

• Bmi-1/hTERT immortalized cell lines serve as reliable models for CF research and drug screening.
• These cell lines faithfully mirror primary cell responses to CFTR modulators.
• Therapeutic strategies targeting nonsense mutations show promise for treating CF patients with limited options.