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DOI: 10.1055/s-2004-819280
Metabolomics of the androgen receptor: Natural mutations of the ligand binding domain (LBD) cause mutation-specific trans-activation profiles in response to virilizing and anabolic androgens
Background: Androgens with different profiles of biological actions (e.g., dihydrotestosterone (DHT), stanozolol (S)) cause distinct activation profiles of structurally different androgen-regulated promoters via the androgen receptor (AR) (1). Mutations of the AR-gene cause androgen insensitivity syndrome (AIS), e.g., by reduced ligand binding. However, the quantiative receptor defect alone is not sufficient in explaining the phenotypic variability of AIS.
Objectives: To investigate whether natural mutations of the AR-gene cause qualitatively specific promoter-activation profiles.
Methods: Transfections of CHO-cells with either wild type or mutant AR expression plasmids containing mutations in the LBD (L712F, M780I, R855H=partial AIS; V866M=complete AIS). Co-transfection of three structurally different androgen-regulated reporter-genes (MMTV, (ARE2)TATA, GRE-OCT) as a model for different natural target genes. Incubation with DHT or S. Three independent triplicate experiments. No activity in the absence of the AR.
Results: Concentration-dependent activation of all three promoters by DHT > S via the wild type AR. Partial activity due to V866M in response to high DHT concentrations, complete inactivation using S. Selectively reduced (ARE2)TATA-activity due to M780I using S. Activity of L712F higher than M780I and R855H activating GRE-OCT. Inverse results using MMTV – and (ARE2)TATA.
Conclusions: We demonstrate for the first time that natural mutations of the AR-LBD cause mutation-specific trans-activation profiles which is further illuminated using different androgenic ligands. Our data strongly suggest that realisation of an AIS-phenotype may not only depend on the quantitative receptor defect, but moreover, may be influenced by selective, mutation-specific profiles of androgen regulated target genes. Therefore, our data provides scientific evidence for the general possibility of developing individual, genotype-guided hormone treatment regimens in steroid receptor mediated diseases.
(1) Holterhus et al. 2003, J Steroid Biochem Mol Biol 82:269–275