Cyclic AMP Phosphodiesterase 4D (PDE4D) Tethers EPAC1 in a Vascular Endothelial Cadherin (VE-Cad)-based Signaling Complex and Controls cAMP-mediated Vascular Permeability

Abstract

Vascular endothelial cell (VEC) permeability is largely dependent on the integrity of VE-cadherin (VECAD)-based intercellular adhesions. Activators of protein kinase A (PKA) or of exchange protein activated by cAMP (EPAC) reduce VEC permeability largely by stabilizing VECAD-based intercellular adhesions. Currently, little is known concerning the nature and composition of the signaling complexes which allow PKA or EPAC to regulate VECAD-based structures and through these actions control permeability. Using pharmacological, biochemical and cell biological approaches we identify and determine the composition and functionality of a signaling complex that coordinate cAMP-mediated control of VECAD-based adhesions and VEC permeability. Thus, we report that PKA, EPAC1 and cyclic nucleotide phosphodiesterase 4D (PDE4D) enzymes integrate into VECAD-based signaling complexes in human arterial endothelial cells (HAECs) V体育官网. Importantly, we show that protein-protein interactions between EPAC1 and PDE4D serve to foster their integration into VECAD-based complexes and allow robust local regulation of EPAC1-based stabilization of VECAD-based adhesions. Of potential translational importance, we mapped the EPAC1 peptide motif involved in binding PDE4D and show that a cell-permeable variant of this peptide antagonizes EPAC1-PDE4D binding and directly alters VEC permeability. Collectively, our data indicate that PDE4D regulates both the activity and subcellular localization of EPAC1 and identify a novel mechanism for regulated EPAC1 signaling in these cells.