Positive epistasis between disease-causing missense mutations and silent polymorphism with effect on mRNA translation...

Area of Science:

• Genetics
• Molecular Biology
• Biochemistry

Background:

• Epistasis describes mutation dependence on genetic context, complicating human disorder phenotypes and disease outcome variations.
• Understanding nonadditive mutation relationships and physiological effects is crucial for predicting phenotypic outcomes.

Purpose of the Study:

• To investigate positive epistasis between intragenic mutations within the cystic fibrosis transmembrane conductance regulator (CFTR) gene.
• To identify mechanisms underlying enhanced CFTR protein expression and activity through combined mutations.

Main Methods:

• Identification of a synonymous single-nucleotide polymorphism (sSNP) affecting CFTR translation speed.
• Analysis of epistatic effects of the sSNP in combination with CF-causing missense mutations.
• Functional studies to elucidate the role of ribosomal velocity in CFTR function.

Main Results:

• A specific sSNP demonstrated positive epistatic effects on certain CF-causing missense mutations in cis.
• Combined mutations led to enhanced CFTR protein expression and activity compared to individual mutations.
• Synergistic alteration of ribosomal velocity was identified as the mechanism, increasing time for domain-domain interactions.

Conclusions:

• Positive epistasis between intragenic CFTR mutations, including an sSNP, can enhance protein function.
• Altered translation speed is a key mechanism driving these epistatic effects, offering potential therapeutic insights for cystic fibrosis.