Ribosomal frameshifting selectively modulates the assembly, function, and pharmacological rescue of a misfolded CFTR...

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• Cystic fibrosis (CF) is primarily caused by cotranslational misfolding of the cystic fibrosis transmembrane conductance regulator (CFTR) chloride channel.
• The most common CF variant, ΔF508, involves misfolding that affects CFTR's translational regulation and quality control.
• The direct impact of nascent polypeptide misassembly on translation machinery activity remains poorly understood.

Purpose of the Study:

• To investigate how RNA structure within the CFTR transcript influences translation and quality control.
• To elucidate the role of ribosomal frameshifting in the context of ΔF508 CFTR misfolding.
• To explore the therapeutic implications of targeting RNA structure for CF treatment.

Main Methods:

• Identification of a structural motif in the CFTR transcript.
• Analysis of ribosomal frameshifting and premature translation termination.
• Assessment of protein-RNA interactions using silent mutations.
• Measurement of ΔF508 CFTR channel gating and response to CFTR modulators.
• Investigation of the role of ER membrane protein complexes.

Main Results:

• A specific RNA structural motif was identified that stimulates -1 ribosomal frameshifting and premature translation termination.
• Disrupting this RNA structure alters the association of nascent ΔF508 CFTR with translation and quality control proteins.
• Modifying the RNA structure enhances ΔF508 CFTR channel function and its rescue by CFTR modulators like Trikafta.
• These effects are modulated by ER membrane protein complexes, influencing ribosome collisions.

Conclusions:

• Ribosomal frameshifting dynamically modulates the assembly, function, and pharmacological rescue of misfolded CFTR variants.
• Interactions between the nascent chain, quality control machinery, and ribosomes can tune translation processivity in response to cotranslational misfolding.
• Targeting RNA structure presents a novel therapeutic strategy for enhancing CFTR function in cystic fibrosis.