Delocalization of Endogenous A-kinase Antagonizes Rap1-Rho-α2C-Adrenoceptor Signaling in Human Microvascular Smooth Muscle Cells.
The second messenger cyclic AMP (cAMP) plays a vital role in the physiology of the cardiovascular system, including vasodilation of large blood vessels. This study focused on cAMP signaling in peripheral blood vessels, specifically in human vascular smooth muscle (microVSM) cells explanted from skin punch biopsy arterioles (also known as resistance vessels) of healthy volunteers. Using these human microVSM we recently demonstrated cAMP activation of exchange protein activated by cAMP (Epac), the Ras-related small GTPase Rap1A, and RhoA-ROCK-F-actin signaling in human microVSM to increase expression and cell surface translocation of functional α2C-adrenoceptors (α2C-ARs) that mediate vasoconstriction. Protein-protein association with the actin-binding protein filamin-2 and phosphorylation of filamin-2 Ser2113by cAMP-Rap1A-Rho-ROCK signaling were necessary for receptor translocation in these cells. Although cAMP activated A-kinase in these cells, these effects were independent of A-kinase, and suggested compartmentalized A-kinase local signaling facilitated by A-kinase anchoring proteins (AKAPs). In this study we globally disrupted A-kinase-AKAP interactions by the anchoring inhibitor decoy peptide Ht31 and examined the effect on α2C-AR expression, translocation, and function in quiescent microVSM treated with the adenylyl cyclase activator and cAMP elevating agent forskolin. The results show that Ht31, but not the control peptide Ht31-P, reduced forskolin-stimulated Ser133phosphorylation of A-kinase substrate CREB, reduced α2C-AR mRNA levels, reduced cell surface translocated receptors, and attenuated agonist-triggered receptor functional responses. Together, the results suggest that compartmentalized cAMP signaling elicits a selective cellular response in microVSM, which may have relevance to arteriole physiological function and responses.
Center for Cardiovascular & Pulmonary Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA ; Faculty of Pharmacy, Department of Pharmacology & Toxicology, Helwan University, Helwan, Egypt.
Hanaa K B
HK
Motawea
Davis Heart and Lung Research Institute, Ohio State University, Columbus, Ohio, USA.
Alisa D
AD
Blazek
Internal Medicine, Ohio State University Wexner Medical Center, Columbus, Ohio, USA.
Matthew J
MJ
Zirwas
Internal Medicine, Ohio State University Wexner Medical Center, Columbus, Ohio, USA.
Adam P
AP
Pleister
Faculty of Pharmacy, Department of Pharmacology & Toxicology, Helwan University, Helwan, Egypt.
Amany A E
AA
Ahmed
Department of Pharmacological and Pharmaceutical Sciences, University of Houston, Texas Medical Center, Houston, Texas, USA.
Bradley K
BK
McConnell
Center for Cardiovascular & Pulmonary Research, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, USA ; Davis Heart and Lung Research Institute, Ohio State University, Columbus, Ohio, USA ; Department of Pediatrics, Ohio State University, Columbus, Ohio, USA.
Maqsood A
MA
Chotani
Arteriole; Ht31; Microcirculation; Resistance vessel; Signal transduction; UK 14, 304; Vascular smooth muscle; Vasoconstriction; cAMP