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The structure of MR in complex with eplerenone.
Structural highlights
DiseaseMCR_HUMAN Defects in NR3C2 are a cause of pseudohypoaldosteronism 1, autosomal dominant (PHA1A) [MIM:177735. A salt wasting disease resulting from target organ unresponsiveness to mineralocorticoids. PHA1A is a mild form characterized by target organ defects confined to kidney. Patients may present with neonatal renal salt wasting with hyperkalaemic acidosis despite high aldosterone levels. These patients improve with age and usually become asymptomatic without treatment.[1] [2] [3] [4] [5] Defects in NR3C2 are a cause of early-onset hypertension with severe exacerbation in pregnancy (EOHSEP) [MIM:605115. Inheritance is autosomal dominant. The disease is characterized by the onset of severe hypertension before the age of 20, and by suppression of aldosterone secretion.[6] [7] [8] [9] FunctionMCR_HUMAN Receptor for both mineralocorticoids (MC) such as aldosterone and glucocorticoids (GC) such as corticosterone or cortisol. Binds to mineralocorticoid response elements (MRE) and transactivates target genes. The effect of MC is to increase ion and water transport and thus raise extracellular fluid volume and blood pressure and lower potassium levels.[10] Publication Abstract from PubMedExcess mineralocorticoid receptor (MR) activation promotes target organ dysfunction, vascular injury and fibrosis. MR antagonists like eplerenone are used for treating heart failure, but their use is limited due to the compound class-inherent hyperkalemia risk. Here we present evidence that AZD9977, a first-in-class MR modulator shows cardio-renal protection despite a mechanism-based reduced liability to cause hyperkalemia. AZD9977 in vitro potency and binding mode to MR were characterized using reporter gene, binding, cofactor recruitment assays and X-ray crystallopgraphy. Organ protection was studied in uni-nephrectomised db/db mice and uni-nephrectomised rats administered aldosterone and high salt. Acute effects of single compound doses on urinary electrolyte excretion were tested in rats on a low salt diet. AZD9977 and eplerenone showed similar human MR in vitro potencies. Unlike eplerenone, AZD9977 is a partial MR antagonist due to its unique interaction pattern with MR, which results in a distinct recruitment of co-factor peptides when compared to eplerenone. AZD9977 dose dependently reduced albuminuria and improved kidney histopathology similar to eplerenone in db/db uni-nephrectomised mice and uni-nephrectomised rats. In acute testing, AZD9977 did not affect urinary Na+/K+ ratio, while eplerenone increased the Na+/K+ ratio dose dependently. AZD9977 is a selective MR modulator, retaining organ protection without acute effect on urinary electrolyte excretion. This predicts a reduced hyperkalemia risk and AZD9977 therefore has the potential to deliver a safe, efficacious treatment to patients prone to hyperkalemia. Preclinical pharmacology of AZD9977: A novel mineralocorticoid receptor modulator separating organ protection from effects on electrolyte excretion.,Bamberg K, Johansson U, Edman K, William-Olsson L, Myhre S, Gunnarsson A, Geschwindner S, Aagaard A, Bjornson Granqvist A, Jaisser F, Huang Y, Granberg KL, Jansson-Lofmark R, Hartleib-Geschwindner J PLoS One. 2018 Feb 23;13(2):e0193380. doi: 10.1371/journal.pone.0193380., eCollection 2018. PMID:29474466[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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