A nonnatural peptide targeting the A-kinase anchoring function of PI3Kγ for therapeutic cAMP modulation in pulmonary cells

A-kinase anchoring proteins (AKAPs) are key orchestrators of cAMP signaling that act by recruiting protein kinase A (PKA) in proximity of its substrates and regulators to specific subcellular compartments. Modulation of AKAPs function offers the opportunity to achieve compartment-restricted modulation of the cAMP/PKA axis, paving the way to new targeted treatments. For instance, blocking the AKAP activity of phosphoinositide 3-kinase y (PI3Ky) improves lung function by inducing cAMP-mediated bronchorelaxation, ion transport, and antiinflammatory responses. Here, we report the generation of a nonnatural peptide, D-retroinverso (DRI)-Pep #20, optimized to disrupt the AKAP function of PI3Ky. DRI-Pep #20 mimicked the native interaction between the N-terminal domain of PI3Ky and PKA, demonstrating nanomolar affinity for PKA, high resistance to protease degradation and high permeability to the pulmonary mucus barrier. DRI-Pep #20 triggered cAMP elevation both in vivo in the airway tract of mice upon intratracheal administration, and in vitro in bronchial epithelial cells of cystic fi brosis (CF) patients. In CF cells, DRI-Pep #20 rescued the defective function of the cAMPoperated channel cystic fi brosis transmembrane conductance regulator, by boosting the efficacy of approved cystic fi brosis transmembrane conductance regulator modulators. Overall, this study unveils DRI-Pep #20 as a potent PI3Ky/PKA disruptor for achieving therapeutic cAMP elevation in chronic respiratory disorders.