Human estrogen receptor regulation in a yeast model system and studies on receptor agonists and antagonists

Lyttle, C. Richard; Damián-Matsumura, Pablo; Juul, H.; Butt, Tauseef R.

doi:10.1016/0960-0760(92)90108-u

Cited by 89 publications

(55 citation statements)

References 28 publications

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“…This system has proved to be a suitable model to evaluate hormone agonistic, synergistic and antagonistic activities (Lyttle et al 1992). The results indicated that 3 GSD was able to induce hER -mediated -galactosidase activity in a dose-response manner (Fig.…”

Section: Discussionmentioning

confidence: 86%

“…Oestrogen-like activity of GSD and its A-ring reduced derivatives was assessed in the yeast expression system as previously reported (Lyttle et al 1992), where Saccharomyces cerevisiae hyperpermeable yeast strain RS 188 N was co-transfected with an expression vector containing the hER , under the control of a yeast copper metallothionein promoter and a -galactosidase reporter vector, expression of which was under the control of oestrogen response elements (EREs). Yeast cultures were grown overnight, as described by Sherman et al (1982), diluted to an optical density (o.d.)…”

Section: Oestrogen-induced Yeast Transactivation Systemmentioning

confidence: 99%

See 1 more Smart Citation

The oestrogenic effects of gestodene, a potent contraceptive progestin, are mediated by its A-ring reduced metabolites

Lemus¹,

Zaga²,

Santillán³

et al. 2000

Journal of Endocrinology

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Gestodene (17 -ethynyl-13 -ethyl-17 -hydroxy-4,15-gonadien-3-one) is the most potent synthetic progestin currently available and it is widely used as a fertility regulating agent in a number of contraceptive formulations because of its high effectiveness, safety and acceptability. The observation that contraceptive synthetic progestins exert hormone-like effects other than their progestational activities, prompted us to investigate whether gestodene (GSD) administration may induce oestrogenic effects, even though the GSD molecule does not interact with intracellular oestrogen receptors (ER).To assess whether GSD may exert oestrogenic effects through some of its neutral metabolites, a series of experimental studies were undertaken using GSD and three of its A-ring reduced metabolites. Receptor binding studies by displacement analysis confirmed that indeed GSD does not bind to the ER, whereas its 3 ,5 -tetrahydro reduced derivative (3 GSD) interacts with a relative high affinity with the ER. The 3 ,5 GSD isomer (3 GSD) also binds to the ER, though to a lesser extent. The ability of the A-ring reduced GSD derivatives to induce oestrogenic actions was evaluated by the use of two different molecular bioassays: (a) transactivation of a yeast system cotransfected with the human ER (hER ) gene and oestrogen responsive elements fused to the -galactosidase reporter vector and (b) transactivation of the hERmediated transcription of the chloramphenicol acetyl transferase (CAT) reporter gene in a HeLa cells expression system. The oestrogenic potency of 3 GSD was also assessed by its capability to induce oestrogen-dependent progestin receptors (PR) in the anterior pituitary of castrated female rats.The results demonstrated that 3 GSD and 3 GSD were able to activate, in a dose-dependent manner, the hERmediated transcription of both the -galactosidase and the CAT reporter genes in the yeast and HeLa cells expression systems respectively. In both assays the 3 derivative of GSD exhibited a significantly greater oestrogenic effect than its 3 isomer, while unchanged GSD and 5 GSD were completely ineffective. Neither 3 GSD nor 3 GSD exhibited oestrogen synergistic actions. Interestingly, the pure steroidal anti-oestrogen ICI-182,780 diminished the transactivation induced by 3 GSD and 3 GSD in the yeast expression system. Furthermore, administration of 3 GSD resulted in a significant increase of oestrogendependent PR in the anterior pituitaries of castrated rats in comparison with vehicle-treated animals. The characteristics of the 3 GSD-induced PR were identical to those induced by oestradiol benzoate.The overall results demonstrate that 3 GSD and its 3 isomeric alcohol specifically bind to the ER and possess a weak intrinsic oestrogenic activity, whereas unmodified GSD does not. The data contribute to a better understanding of the GSD mechanism of action and allow the hypothesis to be advanced that the slight oestrogenlike effects attributable to GSD are mediated by its non-phenolic, tetrahydro reduced metabolites.

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Section: Discussionmentioning

confidence: 86%

Section: Oestrogen-induced Yeast Transactivation Systemmentioning

confidence: 99%

The oestrogenic effects of gestodene, a potent contraceptive progestin, are mediated by its A-ring reduced metabolites

Lemus¹,

Zaga²,

Santillán³

et al. 2000

Journal of Endocrinology

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“…Thus, the alternative ligands ICI 164,384, ICI 182,780, and tamoxifen activate transcription at low doses but diminish transcription at high doses (Lyttle et al 1992, Wang et al 1995.…”

Section: Figurementioning

confidence: 99%

Biochemical origins of the non-monotonic receptor-mediated dose-response

Kohn¹,

Melnick²

2002

Journal of Molecular Endocrinology

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A mathematical model was created to examine how xenobiotic ligands that bind to nuclear receptor proteins may affect transcriptional activation of hormone-regulated genes. The model included binding of the natural ligand (e.g. hormone) and xenobiotic ligands to the receptor, binding of the liganded receptor to receptor-specific DNA response sequences, binding of co-activator or co-repressor proteins (Rp) to the resulting complex, and the consequent transcriptional rate relative to that in the absence of the xenobiotic agent. The model predicted that the xenobiotic could act as a pure agonist, a pure antagonist, or a mixed agonist whose dose-response curve exhibits a local maximum. The response to the agent depends on the affinity of the liganded receptor-DNA complex for binding additional transcription factors (e.g. co-activator proteins). An inverted U-shaped dose-response occurred when basal levels of the natural ligand did not saturate receptor binding sites and the affinity for co-activator is weaker when the xenobiotic ligand is bound to the receptor than when the endogenous ligand is bound. The dose-response curve shape was not dependent on the affinity of the receptor for the xenobiotic agent; alteration of this value merely shifted the curve along the concentration axis. The amount of receptor, the density of DNA response sequences, and the affinity of the DNA-bound receptor for Rp determine the amplitude of the computed response with little overall change in curve shape. This model indicates that a non-monotonic dose-response is a plausible outcome for xenobiotic agents that activate nuclear receptors in the same manner as natural ligands.

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“…Sendo elas, as sequências do fator de transcrição quimérico (LOUVION; HAVAUX-COPF; PICARD, 1993;LYTTLE et al, 1992;NALLEY;JOHNSTON;KODADEK, 2006;QUINTERO et al, 2007;TANAKA et al, 1989) para reconhecimento do indutor estrogênio e a sequência do promotor quimérico cbh1 do T. reesei (CARRARO et al, 1998;HENRIQUE-SILVA et al, 1996;NEVALAINEN;TE'O;BERQQUIST, 2005). PICARD, 1993;TANAKA et al, 1989).…”

Section: Desenho E Construção Do Sistema De Expressãounclassified

“…Alguns trabalhos (LYTTLE et al, 1992;QUINTERO et al, 2007) Figura 29. Determinação da atividade enzimática de cbh1.O transformante 2 foi submetido à indução no meio YP Sacarose 2% sob diferentes concentrações de DES e E2 (zero, 5µM e 10µM).A análise da atividade da celobiohidrolase I foi feita pelo teste de DNS nos intervalos de tempo de 6, 12 e 24 horas, cujo resultado é apresentado no gráfico em µg/mL.…”

Section: Atividade Enzimáticaunclassified

Sistema de expressão induzido por estradiol em <i>Saccharomyces cerevisiae</i>.

Adriani¹

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Human estrogen receptor regulation in a yeast model system and studies on receptor agonists and antagonists

Cited by 89 publications

References 28 publications

The oestrogenic effects of gestodene, a potent contraceptive progestin, are mediated by its A-ring reduced metabolites

The oestrogenic effects of gestodene, a potent contraceptive progestin, are mediated by its A-ring reduced metabolites

Biochemical origins of the non-monotonic receptor-mediated dose-response

Sistema de expressão induzido por estradiol em <i>Saccharomyces cerevisiae</i>.

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