AUTHOR=Cannavo Alessandro , Marzano Federica , Elia Andrea , Liccardo Daniela , Bencivenga Leonardo , Gambino Giuseppina , Perna Claudia , Rapacciuolo Antonio , Cittadini Antonio , Ferrara Nicola , Paolocci Nazareno , Koch Walter J. , Rengo Giuseppe 

TITLE=Aldosterone Jeopardizes Myocardial Insulin and β-Adrenergic Receptor Signaling via G Protein-Coupled Receptor Kinase 2

JOURNAL=Frontiers in Pharmacology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2019.00888

DOI=10.3389/fphar.2019.00888

ISSN=1663-9812

ABSTRACT=<p>Hyperaldosteronism alters cardiac function, inducing adverse left ventricle (LV) remodeling either <italic>via</italic> increased fibrosis deposition, mitochondrial dysfunction, or both. These harmful effects are due, at least in part, to the activation of the G protein-coupled receptor kinase 2 (GRK2). In this context, we have previously reported that this kinase dysregulates both β-adrenergic receptor (βAR) and insulin (Ins) signaling. Yet, whether aldosterone modulates cardiac Ins sensitivity and βAR function remains untested. Nor is it clear whether GRK2 has a role in this modulation, downstream of aldosterone. Here, we show <italic>in vitro</italic>, in 3T3 cells, that aldosterone impaired insulin signaling, increasing the negative phosphorylation of insulin receptor substrate 1 (<sup>ser307</sup>pIRS1) and reducing the activity of Akt. Similarly, aldosterone prevented the activation of extracellular signal-regulated kinase (ERK) and the production of cyclic adenosine 3′,5′-monophosphate (cAMP) in response to the β<sub>1</sub>/β<sub>2</sub>AR agonist, isoproterenol. Of note, all of these effects were sizably reduced in the presence of GRK2-inhibitor CMPD101. Next, in wild-type (WT) mice undergoing chronic infusion of aldosterone, we observed a marked GRK2 upregulation that was paralleled by a substantial β1AR downregulation and augmented <sup>ser307</sup>pIRS1 levels. Importantly, in keeping with the current <italic>in vitro</italic> data, we found that aldosterone effects were wholly abolished in cardiac-specific GRK2-knockout mice. Finally, in WT mice that underwent 4-week myocardial infarction (MI), we observed a substantial deterioration of cardiac function and increased LV dilation and fibrosis deposition. At the molecular level, these effects were associated with a significant upregulation of cardiac GRK2 protein expression, along with a marked β1AR downregulation and increased <sup>ser307</sup>pIRS1 levels. Treating MI mice with spironolactone prevented adverse aldosterone effects, blocking GRK2 upregulation, and thus leading to a marked reduction in cardiac <sup>ser307</sup>pIRS1 levels while rescuing β1AR expression. Our study reveals that GRK2 activity is a critical player downstream of the aldosterone signaling pathway; therefore, inhibiting this kinase is an attractive strategy to prevent the cardiac structural disarray and dysfunction that accompany any clinical condition accompanied by hyperaldosteronism.</p>