Biophysical and aerodynamic properties of a peptide targeting the A-kinase anchoring function of PI3Kγ for pulmonary cAMP modulation.

Cyclic AMP (cAMP) signaling specificity relies on precise spatial regulation mediated by A-kinase anchoring proteins (AKAPs), which localize protein kinase A (PKA) within defined microdomains. Dysregulated AKAP signaling contributes to different pathologies, including chronic inflammatory airway diseases, making AKAP disruptors attractive therapeutic candidates. We previously showed that a cell-permeable PI3Kγ mimetic peptide (PI3Kγ MP, also known as KIT2014) that disrupts the interaction between the AKAP PI3Kγ and PKA enhances β₂-adrenergic receptordriven cAMP signaling to promote airway relaxation, mucus clearance, and reduced inflammation. Here, we investigated the structural, biophysical, and aerodynamic properties of PI3Kγ MP to gain deeper mechanistic insight. The peptide adopted a partially structured conformation essential for PKA binding, assembled into dynamic nanoparticles compatible with epithelial and mucus penetration, and retained biological activity in protease-rich environments, such as cystic fibrosis sputum. Aerodynamic profiling further demonstrated mass median aerodynamic diameters suitable for deep lung deposition upon nebulization. Collectively, these results position PI3Kγ MP as a first-in-class disruptor of the PI3Kγ-PKA complex with strong translational potential as an inhaled therapy for obstructive airway diseases driven by cAMP dysregulation.