In cellulo analyses of the p.Val322Ala mutation on the CFTR protein conformation and activity

Cystic fibrosis is caused by mutations on the Cystic Fibrosis Transmembrane conductance Regulator gene (CFTR). Exonic mutations may have variable effect on the CFTR protein and may alter the normal localization of CFTR on the apical membrane of epithelial cells or/and its function as a chloride channel. Identifying the effect of a missense mutation can be a first step in helping the medical counseling and the therapeutic strategies. In this study, the effect of the c.965T > C exon 8 mutation that induces a valine-to-alanine substitution (p.Val322Ala) into the fifth helix of the first membrane spanning domain was determined by in silico and in cellulo analyses. The confocal microscopy analyses and functionality test showed, in the tested cell line, that this mutation should have no impact on the function of the p.Val322Ala-CFTR protein. However, regarding the importance of this Val322 amino acid in the CFTR protein, precautions and individual follow-up are still required when c.965T > C if associated with other mutation(s).