Mineralocorticoid Receptor Double Mutant with Bound Spironolactone
[MCR_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.     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.   
[MCR_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.
Publication Abstract from PubMed
Ligand binding is the first step in hormone regulation of mineralocorticoid receptor (MR) activity. Here, we report multiple crystal structures of MR (NR3C2) bound to both agonist and antagonists. These structures combined with mutagenesis studies reveal that maximal receptor activation involves an intricate ligand-mediated hydrogen bond network with Asn770 which serves dual roles: stabilization of the loop preceding the C-terminal activation function-2 helix and direct contact with the hormone ligand. In addition, most activating ligands hydrogen bond to Thr945 on helix 10. Structural characterization of the naturally occurring S810L mutant explains how stabilization of a helix 3/helix 5 interaction can circumvent the requirement for this hydrogen bond network. Taken together, these results explain the potency of MR activation by aldosterone, the weak activation induced by progesterone and the antihypertensive agent spironolactone, and the binding selectivity of cortisol over cortisone.
A ligand-mediated hydrogen bond network required for the activation of the mineralocorticoid receptor.,Bledsoe RK, Madauss KP, Holt JA, Apolito CJ, Lambert MH, Pearce KH, Stanley TB, Stewart EL, Trump RP, Willson TM, Williams SP J Biol Chem. 2005 Sep 2;280(35):31283-93. Epub 2005 Jun 20. PMID:15967794
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.