Defective function of the cystic fibrosis-causing missense mutation G551D is recovered by genistein

The patch-clamp technique was used to investigate the effects of the isofla vone genistein on disease-causing mutations (G551D and Delta F508) of the c ystic fibrosis transmembrane conductance regulator (CFTR). In HeLa cells re combinantly expressing the trafficking-competent G551D-CFTR, the forskolin- stimulated Cl currents were small,:and average open probability of G551D-CF TR was P-o = 0.047 +/- 0.019. Addition of genistein activated Cl currents s imilar to 10-fold, and the P-o of G551D-CFTR increased to 0.49 +/- 0.12, wh ich is a P-o similar to wild-type CFTR. In cystic fibrosis (CF) epithelial cells homozygous for the trafficking-impaired Delta F508 mutation, forskoli n and genistein activated Cl currents only after 4-phenylbutyrate treatment . These data suggested that genistein activated CFTR mutants that were pres ent in the cell membrane. Therefore, we tested the effects of genistein in CF patients with the G551D mutation in nasal,potential difference (PD) meas urements in vivo. The perfusion of the nasal mucosa of G551D CF patients wi th isoproterenol had no effect; however, genistein stimulated Cl-dependent nasal PD by, on average, -2.4 +/- 0.6 mV, which corresponds to 16.9% of the responses (to beta-adrenergic stimulation) found in healthy subjects.