Effects of Hormones Targeting Nuclear Receptors on Transcriptional Regulation of the Growth Hormone Gene in the MtT/S Rat Somatotrope Cell Line
| Autor: | Masanori Yoshida, Kinji Inoue, Masato Asai, Yasumasa Iwasaki, Minako Morishita, Yutaka Oiso, Akiko Onishi |
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| Rok vydání: | 2004 |
| Předmět: |
Transcriptional Activation
Receptors Steroid endocrine system medicine.medical_specialty Receptors Retinoic Acid Endocrinology Diabetes and Metabolism Receptors Cytoplasmic and Nuclear Peptide hormone Biology Cell Line Thyroid hormone receptor beta Retinoids Cellular and Molecular Neuroscience Endocrinology Pituitary Gland Anterior Internal medicine medicine Animals Promoter Regions Genetic Glucocorticoids Analysis of Variance Receptors Thyroid Hormone Thyroid hormone receptor Estradiol Estriol Endocrine and Autonomic Systems Sex hormone receptor Hormones Rats Gene Expression Regulation Nuclear receptor Hormone receptor Growth Hormone Triiodothyronine Glucocorticoid Hormone medicine.drug |
| Zdroj: | Neuroendocrinology. 79:229-236 |
| ISSN: | 1423-0194 0028-3835 |
| Popis: | We have examined the effects of nuclear receptor hormones such as glucocorticoid, gonadal steroid hormones, thyroid hormone and retinoids on the transcriptional regulation of the 5′-promoter activity of growth hormone (GH) gene using the MtT/S rat pure somatotrope cell line or MtT/SGL, a subclone of MtT/S in which the rat GH gene 5′-promoter (1.7 Kb)-luciferase fusion gene was stably incorporated. RT-PCR analyses revealed that receptors for all the hormones except androgen receptor were expressed in the cell line. Triiodothyronine (T3, 10 nM) transiently but significantly stimulated the promoter activity of GH gene, whereas retinoic acids (9-cis and all-trans, both 1 µM) showed sustained stimulation. There were no additive effects among the T3, all-trans, and9-cis retinoic acids. Synthetic glucocorticoid hormone dexamethasone (100 nM) showed an inhibitory effect but, interestingly, significantly enhanced T3-stimulated GH promoter activity during long-term incubation. Among the gonadal steroid hormones tested, estradiol and estriol had significant stimulatory effects, and deletion analysis showed that the estrogen effect was maintained with the shortest construct examined (–150 to +6, +1 denotes the transcription start site). These results suggest that thyroid hormone and retinoids stimulate the transcription of GH gene, probably through a common response element, whereas glucocorticoid has both negative and positive effects on GH expression, depending on the combination with other hormones and the time of exposure. Estrogens also have direct stimulatory effects through the proximal promoter region of GH gene. |
| Databáze: | OpenAIRE |
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