Functional regulation of cystic fibrosis transmembrane conductance regulator-containing macromolecular complexes: A small-molecule inhibitor approach

CFTR (cystic fibrosis transmembrane conductance regulator) has been shown to form multiple protein macromolecular complexes with its interacting partners at discrete subcellular microdomains to modulate trafficking, transport and signalling in cells. Targeting protein-protein interactions within these macromolecular complexes would affect the expression or function of the CFTR channel. We specifically targeted the PDZ domain-based LPA₂ (type 2 lysophosphatidic acid receptor)-NHERF2 (Na⁺/H⁺ exchanger regulatory factor-2) interaction within the CFTR-NHERF2-LPA₂- containing macromolecular complexes in airway epithelia and tested its regulatory role on CFTR channel function. We identified a cell-permeable small-molecule compound that preferentially inhibits the LPA₂-NHERF2 interaction. We show that this compound can disrupt the LPA₂-NHERF2 interaction in cells and thus compromises the integrity of macromolecular complexes. Functionally, it elevates cAMP levels in proximity to CFTR and upregulates its channel activity. The results of the present study demonstrate that CFTR Cl^- channel function can be finely tuned by modulating PDZ domain-based protein-protein interactions within the CFTR-containing macromolecular complexes. The present study might help to identify novel therapeutic targets to treat diseases associated with dysfunctional CFTR Cl ^- channels.