Targeting the regulation of CFTR channels

In this issue of the Biochemical Journal, Zhang et al. reveal a new strategy for modifying the regulated function of CFTR (cystic fibrosis transmembrane conductance regulator) on the apical surface of epithelial cells. Simply stated, these authors tested the idea that the cAMP-dependent channel activity of CFTR could be effectively enhanced by disruption of a protein–protein interaction which is normally inhibitory for the production of cAMP. This particular protein–protein interaction [between the PDZ motif of LPA₂ (type 2 lysophosphatidic acid receptor) and the scaffold protein Nherf2 (Na⁺/H⁺ exchanger regulatory factor 2)] is localized in the CFTR interactome on the apical membrane of epithelial cells. Hence disruption of the LPA₂–Nherf2 interaction should lead to a localized elevation in cAMP and, consequently, increased cAMP-dependent CFTR activity on the surface of epithelial cells. Zhang et al. confirmed these expectations for a small-molecule compound targeting the LPA₂–Nherf2 interaction using relevant cultures and tissues thought to model the human respiratory epithelium. The success of this strategy depended on previous knowledge regarding the role for multiple PDZ-motif-mediated interactions in signalling (directly or indirectly) to CFTR. Given the number and diversity of such PDZ-mediated interactions, future structural and computational studies will be essential for guiding the design of specific pharmacological interventions.