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OR24-03 GRK2 Mediates Beta-Adrenergic Receptor Crosstalk to Enhanced Adrenocortical AngII-Dependent Aldosterone Production

Aldosterone is produced by adrenocortical zona glomerulosa (AZG) cells in response to hyperkalemia or angiotensin II (AngII) acting through its type I receptors (AT(1)Rs). AT(1)R is a G protein-coupled receptor (GPCR) that induces aldosterone synthesis and secretion via both G proteins and the GPCR...

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Detalles Bibliográficos
Autores principales: Lymperopoulos, Anastasios, Pollard, Celina M, Pereyra, Janelle M, Desimine, Victoria L, Wertz, Shelby L, Perez, Arianna, Ferraino, Krysten E, Cora, Natalie
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7208074/
http://dx.doi.org/10.1210/jendso/bvaa046.047
Descripción
Sumario:Aldosterone is produced by adrenocortical zona glomerulosa (AZG) cells in response to hyperkalemia or angiotensin II (AngII) acting through its type I receptors (AT(1)Rs). AT(1)R is a G protein-coupled receptor (GPCR) that induces aldosterone synthesis and secretion via both G proteins and the GPCR adapter proteins βarrestins. AZG cells express all three subtypes of β-adrenergic receptor (AR) and respond to catecholamines by producing aldosterone. Being GPCRs, both activated βARs and AT(1)Rs are phosphorylated by GPCR-kinases (GRKs), followed by βarrestin binding to initiate G protein-independent signaling. Herein, we investigated whether the major adrenal GRKs, GRK2 and GRK5, are involved in catecholaminergic regulation of AngII-dependent aldosterone production. We used the human AZG cell line H295R, in which we measured aldosterone secretion via ELISA and synthesis via real-time PCR for steroidogenic acute regulatory (StAR) protein and CYP11B2 (aldosterone synthase) mRNA levels. Isoproterenol (Iso, a βAR full agonist) treatment significantly augmented AngII-dependent aldosterone synthesis (2.2+0.8-fold CYP11B2 & 1.6+0.5-fold StAR mRNA inductions over AngII alone; p<0.05, n=4), as well as secretion (2.3+0.8-fold of vehicle with Iso; 3.2+1.1-fold of vehicle with AngII; 7.4+1.1-fold of vehicle with Iso+AngII, p<0.05 vs. either agent alone; n=5) in H295R cells. Importantly, GRK2, but not the other major GRK isoform expressed in human adrenals GRK5, was indispensable for the catecholamine-mediated enhancement of aldosterone production in response to AngII in H295R cells. Specifically, GRK2 inhibition with the small molecule Cmpd101 abolished Iso effects on AngII-induced aldosterone synthesis and secretion (Iso+AngII-induced aldosterone secretion: 8.1+2.3-fold of vehicle without Cmpd101; 2.8+0.8-fold of vehicle with Cmpd101; p<0.05, n=5). In contrast, GRK5 knockout via CRISPR/Cas9 did not affect the synergism between isoproterenol and AngII in stimulating aldosterone production. Mechanistically, βAR-activated GRK2, but not GRK5, phosphorylated and activated the Ca(2+)-activated chloride channel anoctamine-1 (ANO1), also known as transmembrane member (TMEM)16A, ultimately increasing aldosterone production in H295R cells (Iso+10(–6) M [Ca(2+)]-induced ANO1 activity of Cmpd101-pretreated cells: 55+15 % of non-Cmpd101-pretreated cells; p<0.05, n=5). AngII alone failed to stimulate GRK2 in H295R cells. In conclusion, GRK2 mediates a βAR-AT(1)R signaling crosstalk at the level of ANO1 activation, which results in enhanced aldosterone production in H295R cells. This finding suggests that adrenal GRK2 may be a molecular link connecting the sympathetic nervous and renin-angiotensin systems in the adrenal cortex and that GRK2 inhibition might be therapeutically advantageous for aldosterone suppression.