Studies on the mechanism of glucocorticoid hormone induced alterations in rat thymic transcription—II. Partial purification and characterization of RNA polymerases II from hydrocortisone and control vehicle treated animals
| Autor: | Piatt Mk, William C. Buss, Julie Stepanek, Kenneth Stalter |
|---|---|
| Rok vydání: | 1987 |
| Předmět: |
Amanitins
Hydrocortisone Transcription Genetic Cations Divalent RNA polymerase II Thymus Gland Biochemistry chemistry.chemical_compound Endocrinology In vivo Transcription (biology) RNA polymerase Animals Gene Polymerase biology Temperature RNA Rats Inbred Strains Hydrogen-Ion Concentration Chromatography Ion Exchange Molecular biology In vitro Rats Gene Expression Regulation chemistry biology.protein RNA Polymerase II |
| Zdroj: | Journal of Steroid Biochemistry. 28:129-138 |
| ISSN: | 0022-4731 |
| DOI: | 10.1016/0022-4731(87)90368-2 |
| Popis: | In experiments designed to study the mechanism of glucocorticoid hormone induced reductions in rat thymic transcription, adrenalectomized rats were injected with hydrocortisone (50 mg/kg) or control vehicle 12 h prior to sacrifice. Thymic nuclei were used to prepare soluble nuclear extracts containing RNA polymerase II. Nuclear extract RNA polymerases II were then partially purified (600-fold) on DEAE-Sephadex columns and characterized. The responses of partially purified thymic RNA polymerases II from rats treated in vivo with hydrocortisone or vehicle were similar to: pH, temperature, ionic strength, trypsin proteolysis, and inhibition by alpha-amanitin; however, RNA polymerase II from hydrocortisone treated animals was consistently reduced in activity compared to control RNA polymerase II. Determination of the apparent specific activities of peak RNA polymerase II fractions from DEAE-Sephadex columns suggested that the specific activity of RNA polymerase II from hydrocortisone treated animals was reduced compared to RNA polymerase II activity from control animals. The fact that both nuclear extract and partially purified RNA polymerases II from hydro-cortisone treated rats were reduced in activity when assayed in reconstituted transcriptive systems suggests a denatured, defective or modified RNA polymerase II molecule acting as a transcription inhibitor. Thermally denatured nucleoplasmic RNA polymerase II fractions were shown to interfere with transcription by native nucleoplasmic RNA polymerase II in vitro , but did not appear to inhibit transcription to the degree observed in vitro following in vivo hydrocortisone administration. |
| Databáze: | OpenAIRE |
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