title: Identification and characterization of a ligand-selective mineralocorticoid receptor coactivator.
abstract: The mineralocorticoid receptor (MR) is unique in responding to 2 physiological ligands: aldosterone and cortisol. In epithelial tissues, aldosterone selectivity is determined by the activity of 11β-hydroxysteroid dehydrogenase type 2. In other tissues, cortisol is the primary ligand. To understand the structural determinants of ligand-specific MR activation, we sought to identify coregulatory molecules that interact with the ligand-binding domain (LBD) of the MR. A yeast-2-hybrid (Y2H) kidney cDNA library was screened with the human MR-LBD in the presence of aldosterone and cortisol. One clone, identified as aldosterone-specific in the Y2H assay, exhibited a 7-fold greater response, aldosterone vs. cortisol, in a mammalian-2-hybrid (M2H) assay. This clone encodes the region of the tesmin gene that has 2 leucine-x-x-leucine-leucine (LxxLL) motifs. Full-length tesmin coactivates (>2-fold) MR-mediated transactivation in the presence of aldosterone, but not of cortisol; this specificity is observed with a range of promoters. GST pulldown and coimmunoprecipitation of the MR by tesmin supports a direct interaction, mediated by the 2 LxxLL motifs. Tesmin thus represents a novel MR coregulator that exhibits a differential interaction, providing further evidence of the adoption of ligand-dependent conformations by the MR-LBD.
authors.affiliation: Prince Henry's Institute of Medical Research, Clayton, Victoria, Australia.
authors.forename: Fraser M
authors.initials: FM
authors.lastname: Rogerson
authors.affiliation: Prince Henry's Institute of Medical Research, Clayton, Victoria, Australia.
authors.forename: Yi-Zhou
authors.initials: YZ
authors.lastname: Yao
authors.affiliation: Prince Henry's Institute of Medical Research, Clayton, Victoria, Australia.
authors.forename: Morag J
authors.initials: MJ
authors.lastname: Young
authors.affiliation: Prince Henry's Institute of Medical Research, Clayton, Victoria, Australia peter.fuller@princehenrys.org.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Fuller
mesh_terms: D000450:Aldosterone / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002522:Chlorocebus aethiops; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism; D008668:Metallothionein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D056918:Nuclear Receptor Coactivators / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D018161:Receptors, Mineralocorticoid / Q000235:genetics / Q000378:metabolism*; D013379:Substrate Specificity; D020798:Two-Hybrid System Techniques
chemical_list: D056918:Nuclear Receptor Coactivators; D018161:Receptors, Mineralocorticoid; C119112:tesmin; D000450:Aldosterone; D008668:Metallothionein; D006854:Hydrocortisone
keywords: aldosterone; cortisol; nuclear receptors