Protein kinase A‐mediated phosphorylation of naked cuticle homolog 2 stimulates cell‐surface delivery of transforming growth factor‐α for epidermal growth factor receptor transactivation

Abstract

The classic mode of G protein‐coupled receptor (GPCR)‐mediated transactivation of the receptor tyrosine kinase epidermal growth factor receptor (EGFR) transactivation occurs via matrix metalloprotease (MMP)‐mediated cleavage of plasma membrane‐anchored EGFR ligands. Herein, we show that the Gαs‐activating GPCR ligands vasoactive intestinal peptide (VIP) and prostaglandin E2 (PGE2) transactivate EGFR through increased cell‐surface delivery of the EGFR ligand transforming growth factor‐α (TGFα) in polarizing madin‐darby canine kidney (MDCK) and Caco‐2 cells. This is achieved by PKA‐mediated phosphorylation of naked cuticle homolog 2 (NKD2), previously shown to bind TGFα and direct delivery of TGFα‐containing vesicles to the basolateral surface of polarized epithelial cells. VIP and PGE2 rapidly activate protein kinase A (PKA) that then phosphorylates NKD2 at Ser‐223, a process that is facilitated by the molecular scaffold A‐kinase anchoring protein 12 (AKAP12). This phosphorylation stabilized NKD2, ensuring efficient cell‐surface delivery of TGFα and increased EGFR activation. Thus, GPCR‐triggered, PKA/AKAP12/NKD2‐regulated targeting of TGFα to the cell surface represents a new mode of EGFR transactivation that occurs proximal to ligand cleavage by MMPs.

AKAP12 ameliorates liver injury via targeting PI3K/AKT/PCSK6 pathway

“…A-kinase anchor protein 12 (AKAP12)/Src-suppressed C-kinase substrate (SSeCKS) is a member of the AKAP family and a component of the cytoskeleton structure [ 1 ]. AKAP12 maintains the stability of cells and tissues, and regulates cell proliferation and metastasis through activation of the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) or protein kinase A (PKA)/protein kinase C (PKC) pathways [ [1] , [2] , [3] , [4] ].…”

Electrodeposited magnetic nanoporous membrane for high-yield and high-throughput immunocapture of extracellular vesicles and lipoproteins

“…Western blots were done according to the general protocol described previously 47 . Briefly, proteins were quantified by BCA (Thermo, Cat# 23235) using the manufacturer’s instructions.…”