Receptor- and cellular compartment-specific activation of the cAMP/PKA pathway by α1-adrenergic and ETA endothelin receptors

• Published in: Cellular signalling Vol. 44; pp. 43 - 50
• Main Authors: Martin, Ryan D., Sun, Yalin, Bourque, Kyla, Audet, Nicolas, Inoue, Asuka, Tanny, Jason C., Hébert, Terence E.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.04.2018
• Subjects: Adrenergic receptors; Cardiac hypertrophy; Endothelin receptors; G protein-coupled receptors (GPCRs); Signal compartmentalization; Cardiac hypertrophy; Adrenergic receptors; Signal compartmentalization; G protein-coupled receptors (GPCRs); Endothelin receptors
• ISSN: 0898-6568; 1873-3913
• DOI: 10.1016/j.cellsig.2018.01.002

The signalling functions of many G protein-coupled receptors (GPCRs) expressed in the myocardium are incompletely understood. Among these are the endothelin receptor (ETR) family and α1-adrenergic receptor (α1-AR), which are thought to couple to the G protein Gαq. In this study, we used transcriptome analysis to compare the signalling networks downstream of these receptors in primary neonatal rat cardiomyocytes. This analysis indicated increased expression of target genes of cAMP responsive element modulator (CREM) after 24 h treatment with the α1-AR agonist phenylephrine, but not the ETR agonist endothelin-1, suggesting a specific role for the α1-AR in promoting cAMP production in cardiomyocytes. To validate the difference observed between these two GPCRs, we used heterologous expression of the receptors and genetically encoded biosensors in HEK 293 cell lines. We validated that both α1A- and α1B-AR subtypes were able to lead to the accumulation of cAMP in response to phenylephrine in both the nucleus and cytoplasm in a Gαs-dependent manner. However, the ETR subtype ETA did not affect cAMP levels in either compartment. All three receptors were coupled to Gαq signalling as expected. Further, we showed that activation of PKA in different compartments was α1-AR subtype specific, with α1B-AR able to activate PKA in the cytoplasm and nucleus and α1A-AR only able to in the nucleus. We provide evidence for a pathway downstream of the α1-AR, and show that distinct pools of a receptor lead to differential activation of downstream effector proteins dependent on their cellular compartment. •G protein-coupled receptors that regulate cardiac hypertrophy show distinct signaling properties.•Regulation of cAMP levels by α1-adrenergic receptors is dependent on the presence of Gαs.•α1A-adrenergic receptors increase nuclear and cytoplasmic cAMP levels, but only activate protein kinase A in the nucleus.•α1B-adrenergic receptor increases cAMP levels and activates protein kinase A in both the cytoplasm and nucleus.•Endothelin-A receptor does not regulate cAMP levels or protein kinase A activity.