Mani Orlando, Nashev Lyubomir G, Livelo Christopher, Baker Michael E, Odermatt Alex
Division of Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, Pharmacenter, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland.
Department of Medicine, 0693, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States.
J Steroid Biochem Mol Biol. 2016 May;159:31-40. doi: 10.1016/j.jsbmb.2016.02.017. Epub 2016 Feb 22.
Mineralocorticoid receptors (MR) and glucocorticoid receptors (GR) are descended from a common ancestral corticoid receptor. The basis for specificities of human MR for aldosterone and human GR for glucocorticoids, such as cortisol, bearing 17α-hydroxyl-groups, is incompletely understood. Differences in MR at S843 and L848 and GR at the corresponding P637 and Q642 have been proposed as important in their different responses to glucocorticoids with 17α-hydroxyl-groups. We investigated the impact of these residues on binding affinity (Ki) and transcriptional activation (EC50) of mutants MR-S843P, MR-L848Q and MR-S843P/L848Q and mutants GR-P637S, GR-Q642L and GR-P637S/Q642L in the presence of different corticosteroids. Aldosterone, cortisol and corticosterone had similar affinities for wild-type MR and all mutants, while dexamethasone had increased affinity for the three mutants. However, transactivation of MR-S843P and MR-S843P/L848Q by all four steroids was significantly lower than for wild-type MR. In contrast, transactivation of MR-L848Q tended to be 3-fold higher for cortisol and corticosterone and increased 7-fold for dexamethasone, indicating that MR-L848Q has an increased response to glucocorticoids, while retaining a strong response to aldosterone. Compared to wild-type GR, GR-P637S and GR-Q642L had increased affinities and significantly increased transcriptional activity with aldosterone and corticosterone, and GR-P637S had similar transcriptional activity with cortisol and dexamethasone, while GR-Q642L and GR-P637S/Q642L had a significant decrease in transcriptional activity with cortisol and dexamethasone. 3D-models of these MR and GR mutants revealed that dexamethasone and aldosterone, respectively, fit nicely into the steroid-binding pocket, consistent with the affinity of dexamethasone for MR mutants and aldosterone for GR mutants.
盐皮质激素受体（MR）和糖皮质激素受体（GR）源自共同的祖先皮质激素受体。人类MR对醛固酮以及人类GR对具有17α-羟基的糖皮质激素（如皮质醇）的特异性基础尚未完全明确。有人提出，MR的S843和L848位点以及GR相应的P637和Q642位点的差异，对于它们对具有17α-羟基的糖皮质激素的不同反应至关重要。我们研究了这些残基对突变体MR-S843P、MR-L848Q和MR-S843P/L848Q以及突变体GR-P637S、GR-Q642L和GR-P637S/Q642L在不同皮质类固醇存在下的结合亲和力（Ki）和转录激活（EC50）的影响。醛固酮、皮质醇和皮质酮对野生型MR和所有突变体的亲和力相似，而地塞米松对这三个突变体的亲和力增加。然而，MR-S843P和MR-S843P/L848Q被所有四种类固醇的反式激活显著低于野生型MR。相比之下，MR-L848Q对皮质醇和皮质酮的反式激活倾向于高3倍，对地塞米松的反式激活增加7倍，这表明MR-L848Q对糖皮质激素的反应增强，同时对醛固酮仍保持强烈反应。与野生型GR相比，GR-P637S和GR-Q642L对醛固酮和皮质酮的亲和力增加，转录活性显著增强，GR-P637S对皮质醇和地塞米松具有相似的转录活性，而GR-Q642L和GR-P637S/Q642L对皮质醇和地塞米松的转录活性显著降低。这些MR和GR突变体的三维模型显示，地塞米松和醛固酮分别很好地契合类固醇结合口袋，这与地塞米松对MR突变体的亲和力以及醛固酮对GR突变体的亲和力一致。
