Differential Association of Phosphodiesterase 4D Isoforms with β2-Adrenoceptor in Cardiac Myocytes

Vania De Arcangelis,Ruijie Liu,Dagoberto Soto,Yang Xiang

doi:10.1074/jbc.m109.020388

Vania De Arcangelis, Ruijie Liu + Show 2 more

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https://doi.org/10.1074/jbc.m109.020388

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Abstract

cAMP and protein kinase A (PKA) activation represents a key signaling mechanism upon beta-adrenergic stimulation under stress. Both beta(1)- and beta(2)-adrenoreceptor (ARs) subtypes induce cAMP accumulation, yet play distinct roles in cardiac contraction and myocyte apoptosis. Differences in controlling cAMP/PKA activities through the assembly of complexes between the receptors and cAMP-specific phosphodiesterases contribute to the distinct biological outcomes. Here, we demonstrate that beta(2)ARs form signaling complexes with a set of PDE4D isoforms expressed in cardiac myocytes. PDE4D9 and PDE4D8 bind to the beta(2)AR at resting conditions; however, agonist stimulation induces dissociation of PDE4D9 from the receptor but recruitment of PDE4D8 to the receptor. Agonist stimulation also induces recruitment of PDE4D5 to the beta(2)AR. Moreover, the receptor-associated PDE4D isoforms play distinct roles in controlling cAMP activities and regulating the PKA phosphorylation of the receptor and myocyte contraction rate responses. Knockdown of PDE4D9 with short hairpin RNA enhances the beta(2)AR-induced cAMP signaling, whereas knockdown of PDE4D8 only slightly prolongs the receptor-induced cAMP signaling in myocytes. Inhibition of PDE4D9 and PDE4D5 enhances the base-line levels of contraction rates, whereas inhibition of PDE4D9 and PDE4D8 enhances the maximal contraction rate increases upon activation of beta(2)AR. Our data underscore the complex regulation of intracellular cAMP by beta(2)AR-associated phosphodiesterase enzymes to enforce the specificity of the receptor signaling for physiological responses.

Highlights

Physiological responses in animal hearts [1]. ␤1AR and ␤2AR are highly homologous receptors expressed in animal heart for enhancing cardiac performance. ␤1AR plays a dominant role in stimulating heart rate and strength of myocyte contraction, whereas ␤2AR produces only modest chronotropic effects [1]
Association of PDE4D9 and PDE4D8 with ␤2AR in Cardiac Myocytes at Resting State—Our previous study has identified that phosphodiesterase 4D gene functionally associates with ␤2ARs in cardiac myocytes [5]
PDE4D isoforms play an essential role in regulating local cAMP/protein kinase A (PKA) activities induced by a variety of neurotransmitters and hormones

Summary

Introduction

Physiological responses in animal hearts [1]. ␤1AR and ␤2AR are highly homologous receptors expressed in animal heart for enhancing cardiac performance. ␤1AR plays a dominant role in stimulating heart rate and strength of myocyte contraction, whereas ␤2AR produces only modest chronotropic effects [1]. PDE4 and PDE3 are two major families expressed, which account for more than 90% of PDE activities [3]. These PDEs play a critical role for the subcellular specificity in cAMP signaling by preventing diffusion of cAMP from one microdomain to another [4, 5]. PDE4D splicing variants have been implicated in association with ␤AR subtypes for receptor signaling and function [5]. ␤1AR forms a signaling complex with PDE4D8, which dissociates from the receptor upon agonist stimulation [6]. The differential association of PDE4D isoforms with ␤2AR plays distinct roles in confining the receptor-induced cAMP activities for physiological contraction responses. Our data underscore the complexity of PDE regulation of cellular cAMP to enforce the specificity of ␤AR subtype signaling

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