Document Detail


Hormonal regulation of transcription of rDNA. Inhibition of transcription during glucocorticoid-mediated inhibition of proliferation of lymphosarcoma P1798 cells in culture.
MedLine Citation:
PMID:  6688417     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
A lymphosarcoma cell line designated P1798.S6M has been characterized with respect to glucocorticoid responsiveness in culture. Cells ceased to proliferate in the presence of 10(-7) M dexamethasone. Cell viability remained high and glucocorticoid-sensitive cells could be rescued from cultures treated with dexamethasone for 24 or 48 h. These data indicate that P1798.S6M undergoes reversible arrest in the presence of dexamethasone. The system was used to study the effects of mitotic arrest upon transcription of rDNA. Incorporation of [methyl-3H]methionine into rRNA was rapidly inhibited and pulse-chase experiments indicated that 28 S RNA was not synthesized after 24 h of exposure to dexamethasone. Hybridization studies indicated that the amount of pre-rRNA was reduced by 90 to 95% in cells treated for 24 h. Transcription studies were carried out in isolated nuclei. Twenty-four hours after addition of dexamethasone, template-bound RNA polymerase I activity decreased by 89 to 96%. Total RNA polymerase I activity did not decrease, whereas disengaged nuclear polymerase I activity increased dramatically. Filter hybridization studies indicated that labeling of nascent pre-rRNA chains in vitro was inhibited 93%. These data are interpreted as follows: Dexamethasone reversibly inhibits proliferation of P1798.S6M cells and transcription of rDNA. Total RNA polymerase I activity does not decrease, but the amount of template-bound enzyme is reduced with a concomitant increase in the amount of disengaged polymerase I. This indicates that initiation of transcription is inhibited in cells undergoing mitotic arrest in the presence of dexamethasone.
Authors:
A H Cavannaugh; E A Thompson
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  258     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  1983 Aug 
Date Detail:
Created Date:  1983-10-08     Completed Date:  1983-10-08     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  9768-73     Citation Subset:  IM    
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MeSH Terms
Descriptor/Qualifier:
Animals
Cell Division / drug effects
Cells, Cultured
DNA / metabolism*
DNA, Ribosomal
Dexamethasone / pharmacology
Glucocorticoids / pharmacology*
Lymphoma, Non-Hodgkin / pathology*
Methionine / metabolism
Mice
Neoplasms, Experimental / pathology
Transcription, Genetic / drug effects*
Grant Support
ID/Acronym/Agency:
CA22394/CA/NCI NIH HHS; CA24347/CA/NCI NIH HHS
Chemical
Reg. No./Substance:
0/DNA, Ribosomal; 0/Glucocorticoids; 50-02-2/Dexamethasone; 63-68-3/Methionine; 9007-49-2/DNA

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