title: Functional characterization of the hGRαT556I causing Chrousos syndrome.
abstract: BACKGROUND
  Chrousos syndrome is a rare pathologic condition characterized by generalized, partial resistance of target tissues to glucocorticoids and caused by inactivating mutations of the human glucocorticoid receptor (hGR) gene. A novel case of Chrousos syndrome has been reported in a patient with adrenal incidentaloma, who harboured a heterozygous point mutation in the hGR gene, which resulted in threonine (T) to isoleucine (I) substitution at amino acid position 556 in the ligand-binding domain of the receptor.
  
  
  OBJECTIVE
  To delineate the molecular mechanisms through which the mutant receptor hGRαT556I causes Chrousos syndrome.
  
  
  RESULTS
  Compared with the wild-type receptor, the mutant receptor hGRαT556I demonstrated 50% reduction in its ability to transactivate glucocorticoid-responsive genes and in the affinity for the ligand, 30% increase in the ability to transrepress the nuclear factor-κB-target genes and a 3,4-fold delay in the cytoplasmic-to-nuclear translocation. The mutant receptor hGRαT556I did not exert a dominant negative effect upon the hGRα-mediated transcriptional activity; it preserved its ability to bind to DNA and interacted with the glucocorticoid receptor-interacting protein 1 coactivator mostly through its activation function-1 domain. Structural biology studies revealed that the T556I mutation caused disruption of the hydrogen bond formed by the T556 with the =O group of P637 backbone, which resulted in a significant relocation of the P637-bearing loop. This conformational alteration affected the local 3D arrangement of the receptor and hence the electrostatic surface of the region.
  
  
  CONCLUSIONS
  The hGRαT556I causes Chrousos syndrome by impairing multiple steps of the glucocorticoid signal transduction pathway.
authors.affiliation: Division of Endocrinology, Metabolism and Diabetes, First Department of Pediatrics, University of Athens Medical School, 'Aghia Sophia' Children's Hospital, Athens, Greece.|Division of Endocrinology and Metabolism, Clinical Research Center, Biomedical Research Foundation of the Academy of Athens, Athens, Greece.
authors.forename: Nicolas C
authors.initials: NC
authors.lastname: Nicolaides
authors.affiliation: Division of Endocrinology and Metabolism, Clinical Research Center, Biomedical Research Foundation of the Academy of Athens, Athens, Greece.
authors.forename: Eirini
authors.initials: E
authors.lastname: Skyrla
authors.affiliation: Bioinformatics and Medical Informatics Team, Biomedical Research Foundation of the Academy of Athens, Athens, Greece.
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Vlachakis
authors.affiliation: Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece.
authors.forename: Anna-Maria G
authors.initials: AM
authors.lastname: Psarra
authors.affiliation: Department of Clinical Biochemistry, University of Athens Medical School, 'Attiko' Hospital, Athens, Greece.
authors.forename: Paraskevi
authors.initials: P
authors.lastname: Moutsatsou
authors.affiliation: Division of Endocrinology, Metabolism and Diabetes, First Department of Pediatrics, University of Athens Medical School, 'Aghia Sophia' Children's Hospital, Athens, Greece.|Division of Endocrinology and Metabolism, Clinical Research Center, Biomedical Research Foundation of the Academy of Athens, Athens, Greece.
authors.forename: Amalia
authors.initials: A
authors.lastname: Sertedaki
authors.affiliation: Bioinformatics and Medical Informatics Team, Biomedical Research Foundation of the Academy of Athens, Athens, Greece.|IMGT®, The International ImMunoGeneTics Information System®, Institute of Human Genetics, Montpellier, France.
authors.forename: Sophia
authors.initials: S
authors.lastname: Kossida
authors.affiliation: Division of Endocrinology, Metabolism and Diabetes, First Department of Pediatrics, University of Athens Medical School, 'Aghia Sophia' Children's Hospital, Athens, Greece.|Division of Endocrinology and Metabolism, Clinical Research Center, Biomedical Research Foundation of the Academy of Athens, Athens, Greece.
authors.forename: Evangelia
authors.initials: E
authors.lastname: Charmandari
mesh_terms: D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002522:Chlorocebus aethiops; D003907:Dexamethasone / Q000378:metabolism; D005938:Glucocorticoids / Q000378:metabolism; D045325:HCT116 Cells; D006367:HeLa Cells; D006801:Humans; D008661:Metabolism, Inborn Errors / Q000235:genetics*; D051958:Nuclear Receptor Coactivator 2 / Q000378:metabolism; D017354:Point Mutation; D011965:Receptors, Glucocorticoid / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D005938:Glucocorticoids; C498001:NCOA2 protein, human; D051958:Nuclear Receptor Coactivator 2; D011965:Receptors, Glucocorticoid; C411470:glucocorticoid receptor alpha; D003907:Dexamethasone
keywords: Chrousos syndrome; glucocorticoid receptor; glucocorticoid signalling; hGR mutations