GRK5 is an essential co-repressor of the cardiac mineralocorticoid receptor and is selectively induced by finerenone

Figure 1 G protein-coupled receptor-kinase 5 phosphorylates the cardiac mineralocorticoid receptor in response to finerenone but not to eplerenone. A: Western blotting to confirm G protein-coupled receptor-kinase (GRK)-5 overexpression (OE) with a wild type GRK5-encoding lentivirus or deletion (KO) via a GRK5-targeting CRISPR lentivirus in H9c2 cardiomyocytes. GAPDH blotting is also shown as loading control; B, C: Western blotting for the phosphoserine content of the mineralocorticoid receptor in response to 10 mmol/L finerenone (Fin) or 10 mmol/L eplerenone (Epl) in GRK5-overexpressing (GRK5-OE) or in GRK5-KO or in control, empty virus (EV)-infected H9c2 cells. Representative blots are shown in (B) and the densitometric quantitation of three independent experiments in (C). ^aP < 0.05, vs Epl; n = 3 independent experiments performed in duplicate per cell clone/treatment. EV: Empty vector mock virus-transfected (control) cells; IP: Immunoprecipitation; IB: Immunoblotting.