Glucocorticoid regulation of rat thymus RNA polymerase activity: The role of RNA and protein synthesis

The effects of treatment with phospholipases and extraction with solvents on the activities of RNA polymerases from several rat tissues were studied. The RNA polymerase activity of particulate enzyme from rat liver nuclei was decreased by pretreatment of the enzyme with phospholipase A. The phospholipase decreased the RNA polymerase activity in presence of Mg2+ but not that in presence of Mn2+. The effect of phospholipase A was observed only at low ionic concentration. When the RNA polymerase activity was determined in presence of ammonium sulfate, KCl, or NaCl, phospholipase A did not decrease the RNA polymerase activity. Extraction of the RNA polymerase with ether or iso-octane decreased the RNA polymerase activity to approximately the same extent as the pretreatment with phospholipase A. Phospholipase C produced similar changes as phospholipase A but phospholipase D and lipase did not have any effect on the RNA polymerase activity. Treatment with phospholipase A as well as extraction with solvents enhanced the activity of chromatin-bound RNA polymerase from rat brain, and the RNA polymerase activities of similar preparations from spleen, kidney, heart, and lung were affected only to a relatively smaller extent.

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Stimulation of Protein Synthesis and of RNA Polymerase Activity in the Liver of 3-Methylcholanthrene-Treated Rats

Tumori Journal ◽

10.1177/030089167305900204 ◽

1973 ◽

Vol 59 (2) ◽

pp. 119-127

Author(s):

Claudia Greco ◽

Umberto Ferrini

Keyword(s):

Protein Synthesis ◽

Single Dose ◽

Rna Polymerase ◽

Rat Liver ◽

Transport Mechanism ◽

Polymerase Activity ◽

Isolated Nuclei ◽

Rna Polymerase Activity ◽

Stimulation Of

Following a single dose of 3-methylcholanthrene in rat liver the RNA polymerase activity of Mg++ and Mn++/(NH4)2SO4 - dependent forms is stimulated in isolated nuclei and particularly in the chromatin of extranucleolar fraction. The early enhancement of N-2-fluorenylacetamide microsomal hydroxylating activity does not parallel the shift of the monomer-polysome equilibrium to more aggregated forms. It is suggested that the rate of synthesis and the transport mechanism of RNA messengers into the cytoplasm can be selectively regulated by 3-methylcholanthrene and its metabolites.

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RIBONUCLEIC ACID SYNTHESIS AND OESTRADIOL ACTION IN THE UTERUS

Acta Endocrinologica ◽

10.1530/acta.0.071s396 ◽

1972 ◽

Vol 71 (2_Suppla) ◽

pp. S396-S419 ◽

Cited By ~ 13

Author(s):

Etienne-Emile Baulieu ◽

Charles R. Wira ◽

Edwin Milgrom ◽

Claude Raynaud- Jammet

Keyword(s):

Protein Synthesis ◽

Rna Polymerase ◽

Half Life ◽

Acid Synthesis ◽

Polymerase Activity ◽

Target Cells ◽

Differentiated Cells ◽

Short Half Life ◽

Cellular Machinery ◽

Rna Polymerase Activity

ABSTRACT Some aspects of the fate of oestradiol in uterine cells and of a proposed »cascade« mechanism of its activity are discussed. After a newly described step of entry of the hormone into the target cells, oestradiol is recognized by an intracellular transfer receptor system delivering it selectively to specific Non Histone Chromatin (NHC) protein of very feable abundance, provoking in turn (in a still unknown manner) the transcription of one (or a very few) gene(s). The resulting mRNA(s) would have a short half life and code for Key Intermediary Protein (KIP)(s) (also of very short half life). The latter activates the synthesis of essential component(s) of the cellular machinery in particular rRNAs, which are implicated post-transcriptionally in the generalized protein synthesis and therefore promote the growth of the differentiated cells. The reported changes in uterine RNA polymerase activity and protein synthesis are also discussed in the frame of other mechanisms.

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