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Cyclic AMP (cAMP) activates protein kinase A (PKA) but also the guanine nucleotide exchange factor 'exchange protein directly activated by cAMP' (EPAC1; also known as RAPGEF3). Although phosphorylation by PKA is known to regulate CFTR channel gating - the protein defective in cystic fibrosis - the contribution of EPAC1 to CFTR regulation remains largely undefined. Here, we demonstrate that in human airway epithelial cells, cAMP signaling through EPAC1 promotes CFTR stabilization at the plasma membrane by attenuating its endocytosis, independently of PKA activation. EPAC1 and CFTR colocalize and interact through protein adaptor NHERF1 (also known as SLC9A3R1). This interaction is promoted by EPAC1 activation, triggering its translocation to the plasma membrane and binding to NHERF1. Our findings identify a new CFTR-interacting protein and demonstrate that cAMP activates CFTR through two different but complementary pathways - the well-known PKA-dependent channel gating pathway and a new mechanism regulating endocytosis that involves EPAC1. The latter might constitute a novel therapeutic target for treatment of cystic fibrosis.

Original publication




Journal article


J Cell Sci

Publication Date





2599 - 2612


CFTR, EPAC1, Membrane stability, Protein trafficking, cAMP, A549 Cells, Cyclic AMP, Cyclic AMP-Dependent Protein Kinases, Cystic Fibrosis, Cystic Fibrosis Transmembrane Conductance Regulator, Endocytosis, Epithelial Cells, Guanine Nucleotide Exchange Factors, Humans, Phosphoproteins, Phosphorylation, Protein Binding, Protein Interaction Maps, Respiratory System, Signal Transduction, Sodium-Hydrogen Exchangers