title: Role of Pro-637 and Gln-642 in human glucocorticoid receptors and Ser-843 and Leu-848 in mineralocorticoid receptors in their differential responses to cortisol and aldosterone.
abstract: 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.
authors.affiliation: Division of Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, Pharmacenter, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland.
authors.forename: Orlando
authors.initials: O
authors.lastname: Mani
authors.affiliation: Division of Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, Pharmacenter, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland.
authors.forename: Lyubomir G
authors.initials: LG
authors.lastname: Nashev
authors.affiliation: Department of Medicine, 0693, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States.
authors.forename: Christopher
authors.initials: C
authors.lastname: Livelo
authors.affiliation: Department of Medicine, 0693, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093, United States. Electronic address: mbaker@ucsd.edu.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Baker
authors.affiliation: Division of Molecular and Systems Toxicology, Department of Pharmaceutical Sciences, Pharmacenter, University of Basel, Klingelbergstrasse 50, 4056 Basel, Switzerland. Electronic address: alex.odermatt@unibas.ch.
authors.forename: Alex
authors.initials: A
authors.lastname: Odermatt
mesh_terms: D000450:Aldosterone / Q000502:physiology*; D019943:Amino Acid Substitution; D001665:Binding Sites; D017124:Conserved Sequence; D003907:Dexamethasone; D005973:Glutamine / Q000737:chemistry; D057809:HEK293 Cells; D006801:Humans; D006854:Hydrocortisone / Q000502:physiology*; D006860:Hydrogen Bonding; D007930:Leucine / Q000737:chemistry; D008958:Models, Molecular; D016297:Mutagenesis, Site-Directed; D011392:Proline / Q000737:chemistry; D011485:Protein Binding; D011965:Receptors, Glucocorticoid / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018161:Receptors, Mineralocorticoid / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012694:Serine / Q000737:chemistry; D040681:Structural Homology, Protein; D015533:Transcriptional Activation
chemical_list: D011965:Receptors, Glucocorticoid; D018161:Receptors, Mineralocorticoid; D005973:Glutamine; D012694:Serine; D000450:Aldosterone; D003907:Dexamethasone; D011392:Proline; D007930:Leucine; D006854:Hydrocortisone
keywords: Aldosterone; Cortisol; Evolution; Glucocorticoid receptor; Mineralocorticoid receptor; Site-directed mutagenesis; Structural modelling