Regulation of growth hormone gene expression: synergistic effects of thyroid and glucocorticoid hormones.
AUTOR(ES)
Martial, J A
RESUMO
Cultured rat pituitary cells (GC) respond to thyroid and glucocorticoid hormones by increases in growth hormone production and growth hormone mRNA. When these cells are transferred from medium containing normal animal serum (with 1.8 mug of thyroxine per dl) to a medium containing serum from a thyroidectomized calf, "hypothyroid medium" (with no detectable thyroid hormone), growth hormone production decreases markedly. In cells maintained for 5 days in hypothyroid medium, triiodothyronine induces within 50 hr a 17-fold increase in growth hormone production whereas glucocorticoids, during the same time, produce a negligible (3-fold or less) stimulation. In combination, the two hormones promote a 45-fold stimulation. In all instances the changes in growth hormone production are paralleled by changes in the levels of growth hormone mRNA as measured by cell-free translation. The transfer to hypothyroid medium and the hormonal induction do not affect the relative activities of other mRNAs whose products are detectable on polyacrylamide gels. These studies indicate that thyroid hormone can be an activator of the expression of the growth hormone gene. The results also show that triiodothyronine controls the magnitude of the effect of glucocorticoids on growth hormone mRNA, and provide a model for "permissive" triiodothyronine action. The synergistic effect of these two classes of hormone suggests that they increase levels of growth hormone mRNA by different mechanisms.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=431926Documentos Relacionados
- Regulation of growth hormone messenger RNA by thyroid and glucocorticoid hormones.
- Glucocorticoid and thyroid hormones transcriptionally regulate growth hormone gene expression.
- Dexamethasone regulation of glycosaminoglycan synthesis in cultured human skin fibroblasts. Similar effects of glucocorticoid and thyroid hormones.
- Posttranscriptional regulation of rat growth hormone gene expression: increased message stability and nuclear polyadenylation accompany thyroid hormone depletion.
- Tissue-specific regulation of avian glutamine synthetase expression during development and in response to glucocorticoid hormones.