Distinguishing androgen receptor agonists and antagonists: Distinct mechanisms of activation by medroxyprogesterone acetate and dihydrotestosterone
Por:
Kemppainen J.A., Langley E., Wong C.-I., Bobseine K., Kelce W.R., Wilson E.M.
Publicada:
1 ene 1999
Resumen:
Natural and pharmacological androgen receptor (AR) ligands were tested for their ability to induce the AR NH2-terminal and carboxyl-terminal (N/C) interaction in a two-hybrid protein assay to determine whether N/C complex formation distinguishes in vivo AR agonists from antagonists. High-affinity agonists such as dihydrotestosterone, mibolerone, testosterone, and methyltrienolone at concentrations between 0.1 and 1 nM induce the N/C interaction more than 40-fold. The lower affinity anabolic steroids, oxandrolone and fluoxymesterone, require concentrations of 10-100 nM for up to 23-fold induction of the N/C interaction. However no N/C interaction was detected in the presence of the antagonists, hydroxyflutamide, cyproterone acetate, or RU56187, at concentrations up to 1 ?M, or with 1 ?M estradiol, progesterone, or medroxyprogesterone acetate; each of these steroids at 1- 500 nM inhibited the dihydrotestosterone-induced N/C interaction, with medroxyprogesterone acetate being the most effective. In transient and stable cotransfection assays using the mouse mammary tumor virus reporter vector, all ligands displayed concentration-dependent AR agonist activity that paralleled induction of the N/C interaction, with antagonists and weaker agonists failing to induce the N/C interaction. AR dimerization and DNA binding in mobility shift assays and AR stabilization reflected, but were not dependent on, the N/C interaction. The results indicate that the N/C interaction facilitates agonist potency at low physiological ligand concentrations as detected in transcription, dimerization/DNA binding, and stabilization assays. However the N/C interaction is not required for agonist activity at sufficiently high ligand concentrations, nor does its inhibition imply antagonist activity.
Filiaciones:
Kemppainen J.A.:
Labs. for Reproductive Biology, Department of Pediatrics, University of North Carolina, Chapel Hill, NC 27599, United States
Langley E.:
Labs. for Reproductive Biology, Department of Pediatrics, University of North Carolina, Chapel Hill, NC 27599, United States
Dept. of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, United States
Depto. de Biotecnología, Inst. de Invest. Biomédicas, Univ. Nac. Autonoma de Mexico, México, D. F., Mexico
Wong C.-I.:
Labs. for Reproductive Biology, Department of Pediatrics, University of North Carolina, Chapel Hill, NC 27599, United States
Bobseine K.:
Endocrinology Branch, Reproductive Toxicology Division, Natl. Hlth./Environ. Effects Res. L., Research Triangle Park, NC 27711, United States
Kelce W.R.:
Endocrinology Branch, Reproductive Toxicology Division, Natl. Hlth./Environ. Effects Res. L., Research Triangle Park, NC 27711, United States
Monsanto Company, 645 South Newstead Avenue, St. Louis, MO 63110, United States
Wilson E.M.:
Labs. for Reproductive Biology, Department of Pediatrics, University of North Carolina, Chapel Hill, NC 27599, United States
Dept. of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC 27599, United States
Labs. for Repro. Biology, CB 7500, Medical Sciences Research Building, University of North Carolina, Chapel Hill, NC 27599, United States
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