Trimethylangelicin promotes the functional rescue of mutant F508del CFTR protein in cystic fibrosis airway cells.

Cystic Fibrosis Transmembrane conductance Regulator (CFTR) carrying the F508del mutation is retained in endoplasmic reticulum and fails to traffic to the cell surface where it functions as a PKA activated chloride channel. Pharmacological correctors that rescue the trafficking of F508del CFTR may overcome this defect; however the rescued F508del CFTR still displays reduced chloride permeability. Therefore, a combined administration of correctors and potentiators of the gating defect is ideal. We recently found that 4,6,4'-trimethylangelicin (TMA), beside inhibiting the expression of the IL-8 gene in airway cells in which the inflammatory response was challenged with P. aeruginosa, also potentiates the cAMP/PKA-dependent activation of wild type CFTR or F508del CFTR that has been restored to the plasma membrane. Here, we demonstrate that long preincubation with nanomolar concentrations of TMA, is able to effectively rescue both F508del CFTR-dependent chloride secretion and F508del CFTR cell surface expression in both primary or secondary airway cell monolayers homozygous for F508del mutation. The correction effect of TMA seems to be selective for CFTR and persisted for 24 hours after washout. Altogether, the results suggest that TMA, besides its anti-inflammatory and potentiator activities also displays corrector properties.