Transcriptional and posttranscriptional mechanisms of glucocorticoid-mediated repression of phosphoenolpyruvate carboxykinase gene expression in adipocytes
| Autor: | Jocelyne Antras-Ferry, Danielle Robin, Claude Forest, Sylvie Franckhauser-Vogel, Pierre Robin |
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| Rok vydání: | 1997 |
| Předmět: |
medicine.medical_specialty
Time Factors Transcription Genetic Biology Cycloheximide Biochemistry Dexamethasone chemistry.chemical_compound Mice Internal medicine Gene expression Protein biosynthesis medicine Adipocytes Animals Molecular Biology Psychological repression Glucocorticoids Anisomycin Protein Synthesis Inhibitors Dose-Response Relationship Drug Isoproterenol Proteins Cell Biology Adrenergic beta-Agonists Endocrinology chemistry Puromycin Protein Biosynthesis Phosphoenolpyruvate Carboxykinase (GTP) Phosphoenolpyruvate carboxykinase hormones hormone substitutes and hormone antagonists Glucocorticoid medicine.drug |
| Zdroj: | Journal of cellular biochemistry. 66(3) |
| ISSN: | 0730-2312 |
| Popis: | Glucocorticoids exert pleiotropic effects, among which negative regulation of transcription has been recognized as of crucial importance. While glucocorticoids induce phosphoenolpyruvate carboxykinase (PEPCK) gene expression in liver cells, it represses gene activity in adipose cells. We used the 3T3-F442A adipocytes to analyze the underlying mechanisms in these cells, the synthetic glucocorticoid dexamethasone exerts a dominant repression either on basal or on beta-agonist stimulation of PEPCK gene expression. To determine whether glucocorticoid action required protein synthesis, we employed cycloheximide, anisomycin, and puromycin, three different translation inhibitors. None of these affected induction by isoprenaline or repression by dexamethasone of isoprenaline stimulation. In contrast, dexamethasone inhibitory action on basal PEPCK mRNA was totally prevented by the three translation inhibitors. Time courses of glucocorticoid action on basal and on induction by beta-agonist were similar. Half-maximal effect of dexamethasone on isoprenaline-induced PEPCK mRNA was obtained at about 10 nM, a tenfold higher concentration than that observed for the reduction of basal mRNA. Using the transcription inhibitor DRB, we showed that dexamethasone did not alter mRNA half-life, while isoprenaline strongly stabilized mRNA. In a 3T3-F442A stable transfectant bearing -2,100 base pairs of the PEPCK promoter fused to the chloramphenicol acetyltransferase (CAT) gene, isoprenaline stimulated CAT activity, whereas dexamethasone reduced basal and isoprenaline-induced CAT expression. Hence, beta-agonists exert both transcriptional and posttranscriptional regulation, while glucocorticoid action is purely transcriptional. However, mechanisms of glucocorticoid repression of basal and of beta-agonist stimulation appear different. |
| Databáze: | OpenAIRE |
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