Work

Protein Kinase A and assembly of an ABCC4 protein network

Year: 2025

Type: article

Abstract: Cyclic AMP (cAMP) compartmentalization at the plasma membrane employs export by ABCC4, yet the protein machinery that creates spatially restricted signaling has remained unclear. We show that robust PKA activation increases ABCC4 at the cell surface and assembles a PDZ-dependent macromolecular complex that constrains ABCC4 mobility and stabilizes the transporter. Using Avi-tag crosslinking/AP-MS and APEX proximity labeling, we map a PKA-induced ABCC4 neighborhood enriched for PDZ-domain scaffolds that couple ABCC4 to actin and cell junctions. SCRIB emerges as a previously unrecognized interactor whose depletion lowers surface ABCC4 and blunts ABCC4-dependent drug resistance. Deleting the ABCC4 PDZ motif accelerates lateral diffusion ~4-fold, halves protein half-life, and attenuates PKA-stimulated increases in surface ABCC4 and cAMP efflux, establishing a requirement for the PDZ motif in optimal export under PKA drive. Finally, the selective ABCC4 inhibitor Ceefourin-2 lowers ABCC4’s melting temperature and dismantles the actin/junction–enriched neighborhood, revealing a non-classical small molecule inhibitory mechanism based on network disruption. These findings define a PKA-driven, PDZ-dependent ABCC4 protein neighborhood that stabilizes the transporter and optimizes cAMP efflux—an advance over prior work that localized ABCC4 but lacked a mechanistic blueprint for its membrane microdomain organization. cAMP export by ABCC4 is critical for localized signaling. Here, the authors revealed that PKA activation drives ABCC4 to the plasma membrane and organizes a PDZ-dependent protein network with actin cytoskeleton and scaffolds, like SCRIB, that stabilize the transporter and optimize cAMP efflux. Furthermore, the authors show that the potent ABCC4 inhibitor Ceefourin 2 disrupts this network, revealing a non-canonical mechanism of ABCC4 inhibition.

Source: Nature Communications

DOI: 10.1038/s41467-025-66877-4