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Aldosterone binding to G Protein Estrogen Receptor‐GPER
Author(s) -
Ding Qingming,
Chorazyczewski Jozef,
Gros Robert,
Feldman Ross
Publication year - 2019
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2019.33.1_supplement.503.9
Subject(s) - gper , radioligand , agonist , aldosterone , receptor , binding site , mineralocorticoid receptor , biology , chemistry , estrogen receptor , endocrinology , biochemistry , genetics , cancer , breast cancer
MR‐independent effects of aldosterone acting through GPER have been appreciated since 2011. However, whether this related to direct aldosterone‐GPER binding has been disputed. Two previous radioligand studies failed to demonstrate direct aldosterone binding to a putative GPER. However, in neither study was it demonstrated that the radioligand used, bound to a physiological receptor. Further, both utilized 3 H estradiol‐ whose low potency for GPER binding would not be expected to allow GPER receptor identification using vacuum filtration methods related to its high off‐rates. Therefore to determine if aldosterone did bind to GPER, we studied its displacement of [ 3 H] 2‐methoxyestradiol binding ([ 3 H]2ME ‐ a higher affinity GPER‐selective agonist) in SF9 cells with heterologous GPER expression mediated by baculovirus. In this model system, following GPER gene transfer, [ 3 H]2ME demonstrated saturable and reversible binding to a high affinity population of receptors with a Kd = 3.4±0.4 nM and Bmax = 645±49 fmol/mg. In the absence of baculovirus GPER gene transduction, no high affinity [ 3 H]2ME binding was demonstrable in SF9 cells. [ 3 H]2ME binding was guanine‐nucleotide sensitive with a 43±8% reduction in high affinity binding in the presence of GppNHp (100μM). High affinity [ 3 H]2ME binding was displaceable by 2ME [with an IC50 comparable to the determined Kd (1.3±0.4 nM)], the GPER agonist G1, the GPER antagonist G15, estradiol (E2) and aldosterone (Aldo) but not by hydrocortisone (HC) with an order of potency of (2ME>Aldo>E2=G1>G15>>HC). In summary, we demonstrate high affinity [ 3 H]2ME binding to GPER with an order of potency for aldosterone vs. estradiol (vs. hydrocortisone) that parallels the order of potency of their functional effects in previously studied models. These data support the hypothesis that aldosterone mediates its GPER‐dependent effects by direct binding to the receptor. Support or Funding Information Heart and Stroke Foundation of Canada This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .