[Binding of glucocorticoid-receptor complexes with the acceptor zones of nuclei and effect of glucocorticoids on RNA synthesis in hormone-sensitive and hormone-resistant cell populations].
The binding of free radioactive glucocorticoid and the glucocorticoid-receptor complex to rat liver nuclei was studied in vitro. The binding is non-saturated and independent of preliminary injection of the "cold" hormone. In the course of DNA hydrolysis the amount of the radioactive hormone bound to the chromatin moiety in vivo remains practically unchanged relatively to the initial radioactivity of the protein. The liberation of the nuclei into a cell-free medium and the effect of DNAase I on the nuclei are associated with the redistribution of the hormone-receptor complex in the chromatin molecule and with the appearance of new, previously masked acceptor zones of the hormone binding. During the first 1-2 hours following the hormone injection the endogenous RNA-synthesizing activity of the nuclei is decreased. The increase of RNA synthesis in liver nuclei occurs not earlier than 3 hours after the injection. In Zajdela hepatoma nuclei the repression of RNA synthesis persists as long as 3 hours after the injection of dexamethasone. When RNA synthesis is determined in the nuclei in the presence of exogenous RNA-polymerase of E. coli in vitro, the increase in nuclear RNA synthesis can be observed beginning with the 30th min after the hormone injection. It is assumed that this effect is due to conformational changes in the chromatin structure, which are concomitant with the initial steps of association of the hormone-receptor complex.
D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D002843:Chromatin / Q000187:drug effects; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D004351:Drug Resistance; D004926:Escherichia coli / Q000201:enzymology; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008114:Liver Neoplasms, Experimental / Q000378:metabolism*; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D011965:Receptors, Glucocorticoid / Q000187:drug effects / Q000378:metabolism*; D011987:Receptors, Steroid / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects*
D002843:Chromatin; D011965:Receptors, Glucocorticoid; D011987:Receptors, Steroid; D003907:Dexamethasone; D012321:DNA-Directed RNA Polymerases
Sviazyvanie gliukokortikoid-retseptornykh kompleksov aktseptornymi zonami iader i vliianie gliukokortikoidov na sintez RNK v chuvstvitel'nykh i gormonorezistentnykh kletochnykh populiatsiiakh.