Mutation of the androgen receptor at amino acid 708 (Gly-->Ala) abolishes partial agonist activity of steroidal antiandrogens.
Mutation of a single amino acid in the ligand-binding domain (LBD) of the human androgen receptor (hAR) can induce functional abnormalities in androgen binding, stabilization of active conformation, or interaction with coactivators. The Gly708Ala and Gly708Val substitutions are associated with partial and complete androgen insensitivity syndromes, respectively. In this work, we introduced Ala, Val, and aromatic Phe mutations at position 708 on helix H3 of the hAR-LBD and tested the functional and structural consequences on hAR activity in the presence of steroidal or nonsteroidal agonists and antagonists. The residues involved in the specific recognition of these androgen ligands were identified and analyzed in the light of in vitro biological experiments and the 3D hAR-LBD structure. Our study demonstrated that the Gly708Ala mutation influenced the agonist versus antagonist activity of the ligands and confirmed the crucial role of this residue within the ligand-binding pocket (LBP) in the modulation of androgen agonists. The Gly708Ala mutation transformed the antiandrogen cyproterone acetate (CPA), a partial agonist, into a pure antiandrogen, and the pure nonsteroidal antiandrogen hydroxyflutamide in a partial agonist. From the docking studies, we suggest that CPA acts on AR through the novel mechanism called "passive antagonism".
Terouanne
Béatrice
B
Institut National de la Santé et de la Recherche Médicale U439, Montpellier France.
Nirdé
Philippe
P
Rabenoelina
Fanja
F
Bourguet
William
W
Sultan
Charles
C
Auzou
Gilles
G
D000409:Alanine / Q000235:genetics; D019943:Amino Acid Substitution; D000726:Androgen Antagonists / Q000494:pharmacology*; D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002522:Chlorocebus aethiops; D017373:Cyproterone Acetate / Q000494:pharmacology; D005998:Glycine / Q000235:genetics; D006801:Humans; D015741:Metribolone / Q000494:pharmacology; D008958:Models, Molecular; D009154:Mutation; D011487:Protein Conformation / Q000187:drug effects; D011944:Receptors, Androgen / Q000737:chemistry / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D045165:Testosterone Congeners / Q000494:pharmacology; D015533:Transcriptional Activation / Q000187:drug effects; D014162:Transfection; D014316:Tritium
D000726:Androgen Antagonists; D011944:Receptors, Androgen; D045165:Testosterone Congeners; D014316:Tritium; D015741:Metribolone; D017373:Cyproterone Acetate; D000409:Alanine; D005998:Glycine