A potential role of tyrosine phosphorylation in the function of the cystic fibrosis transmembrane conductance regulator (CFTR)

The role of tyrosine phosphorylation (pTyr) in the function of the cystic fibrosis transmembrane conductance regulator (CFTR) is unclear, as both genistein and sodium orthovanadate are reported to increase CFTR function. We investigated the role of pTyr in CFTR regulation in native human bronchial epithelial (HBE) cells using the tyrosine phosphatase inhibitor phenylarsine oxide (PAO). CFTR function was analysed using the whole cell patch clamp technique with a high sodium chloride (NaCl) bath solution and a cesium chloride (CsCl) pipette solution. It was hypothesised that PAO treatment would increase CFTR activity, resulting in an increase in the CFTR‐mediated outward and inward conductances (G out and G in , respectively). However, pre‐incubating cells in 10μM PAO prior to stimulation with 10μM forskolin/100μM IBMX resulted in a significant decrease in G out from 1090 ± 240 (n = 19) to 170 ± 43 μS/cm 2 (n = 17) (P<0.005 unpaired t‐test) and G in from 931 ± 207 to 214 ± 45 μS/cm 2 (P<0.005 unpaired t‐test). These data suggest that increased tyrosine phosphorylation inhibits CFTR, either through altering the phosphorylation of CFTR itself or an accessory protein. CFTR is known to be regulated by a number of accessory proteins, and future work will examine whether changes in tyrosine phosphorylation alters the interaction of CFTR with these. Funded by the BBSRC and Wellcome Trust.