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A Long Lasting beta(1) Adrenergic Receptor Stimulation of cAMP/Protein Kinase A (PKA) Signal in Cardiac Myocytes
Journal article   Open access   Peer reviewed

A Long Lasting beta(1) Adrenergic Receptor Stimulation of cAMP/Protein Kinase A (PKA) Signal in Cardiac Myocytes

Qin Fu, Sungjin Kim, Dagoberto Soto, Vania De Arcangelis, Lisa DiPilato, Shubai Liu, Bing Xu, Qian Shi, Jin Zhang and Yang K. Xiang
The Journal of biological chemistry, Vol.289(21), pp.14771-14781
05/23/2014
DOI: 10.1074/jbc.M113.542589
PMCID: PMC4031532
PMID: 24713698
url
https://doi.org/10.1074/jbc.M113.542589View
Published (Version of record) Open Access

Abstract

Small-molecule, ligand-activated G protein-coupled receptors are generally thought to be rapidly desensitized within a period of minutes through receptor phosphorylation and internalization after repeated or prolonged stimulation. This transient G protein-coupled receptor activation remains at odds with many observed long-lasting cellular and physiological responses. Here, using live cell imaging of cAMP with a FRET-based biosensor and myocyte contraction assay, we show that the catecholamine-activated beta(1) adrenergic receptor (beta(1)AR) continuously stimulates second messenger cAMP synthesis in primary cardiac myocytes and neurons, which lasts for more than 8 h (a decay t(1/2) of 3.9 h) in cardiac myocytes. However, the beta(1)AR-induced cAMP signal is counterbalanced and masked by the receptor-bound phosphodiesterase (PDE) 4D8-dependent cAMP hydrolysis. Inhibition of PDE4 activity recovers the receptor-induced cAMP signal and promotes contractile response in mouse hearts during extended periods of agonist stimulation. beta(1)AR associates with PDE4D8 through the receptor C-terminal PDZ motif-dependent binding to synaptic-associated protein 97 (SAP97). Knockdown of SAP97 or mutation of the beta(1)AR PDZ motif disrupts the complex and promotes sustained agonist-induced cAMP activity, PKA phosphorylation, and cardiac myocyte contraction response. Together, these findings unveil a long lasting adrenergic signal in neurons and myocytes under prolonged stimulation and an underappreciated role of PDE that is essential in classic receptor signaling desensitization and in maintaining a long lasting cAMP equilibrium for ligand-induced physiological response.
Biochemistry & Molecular Biology Life Sciences & Biomedicine Science & Technology

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