scholarly journals Regulation of ribonucleic acid synthesis by polyamines. Reversal by spermine of inhibition by methylglyoxal bis(guanylhydrazone) of ribonucleic acid synthesis and histone acetylation in rabbit heart

1975 ◽  
Vol 152 (1) ◽  
pp. 91-98 ◽  
Author(s):  
C M Caldarera ◽  
A Casti ◽  
C Guarnier ◽  
G Moruzzi

The relationship between polyamines and RNA synthesis was studied by considering the action of spermine on histone acetylation in perfused heart. In addition, the effect of methylglyoxal bis(guanylhydrazone), inhibitor of putrescine-activated S-adenosylmethionine decarboxylase activity, on RNA and polyamine specific radioactivity and on acetylation of histone fractions was also investigated in perfused heart. Different concentrations of spermine and/or methylglyoxas bis(guanylhydrazone) were injected into the heart, 15 min after beginning the perfusion. The results demonstrate that spermine stimulates the specific radioactivity of RNA of subcellular fractions. Acetylation of the arginine-rich histone fractions, involved in the regulation of RNA transcription, is enhanced by spermine. The perfusion with methylglyoxal bis(guanylhydrazone) causes a decrease in the specific radioactivity of polyamines and RNA, and in acetylation of histone fractions. However, spermine is able to reverse the methylglyoxal bis(guanylhydrazone) inhibition when injected simultaneously. From these results we may assume a possible role for spermine in the regulation of RNA transcription.

1979 ◽  
Vol 178 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Torsten Yngner ◽  
Claes Engelbrecht ◽  
Lillemor Lewan ◽  
Jan-Erik Annerfeldt

The balance between anabolism and catabolism of [5-3H]uridine was studied in the mouse after partial hepatectomy. Labelling of RNA and UDP-glucose was determined and evaluated in relation to changes in the specific radioactivity of UTP. The amounts of labelled catabolic products of uridine were increased several-fold in liver and blood after partial hepatectomy. The specific radioactivity of RNA decreased to about 60% of the control value at 6h and was in the same range as that of control liver at 24h after operation. Decreased labelling of RNA and UDP-glucose was attributable to decreased specific radioactivity of UTP. No changes in the size of the UTP pool or in the balance between uridine anabolism and catabolism were found that could explain the decreased specific radioactivity of UTP. Rather, the alterations in the labelling of this metabolite induced by the partial hepatectomy may be related to decreased phosphorylating capacity in the liver cells and/or dilution of the labelled precursor in an expanded uridine pool. The enhanced amounts of uridine catabolic products in liver and blood were probably a consequence of accumulation and altered incorporation of the metabolites from the blood into the liver cells. Despite the increased amounts of labelled catabolic products and the decreased labelling of RNA, the results reported here actually suggest decreased uridine catabolism and slightly increased RNA synthesis in mouse liver after partial hepatectomy. The results stress the importance of proper controls in determination of nucleic acid synthesis and in metabolic studies by use of labelled precursors.


1977 ◽  
Vol 168 (3) ◽  
pp. 341-345 ◽  
Author(s):  
A Corti ◽  
A Casti ◽  
G Mezzetti ◽  
N Reali ◽  
G Orlandini ◽  
...  

Treatment of perfused rabbit heart with reserpine causes a decrease of incorporation of labelled precursors into RNA species of subcellular fractions and polyamines. Ornithine decarboxylase, S-adenosylmethionine decarboxylase and cytoplasmic Mn2+-stimulated polyadenylate polymerase activities are not modified. Addition of noradrenaline to reserpine-treated perfused hearts enhances, compared with the control, the incorporation of precursor into RNA in all subcellular fractions other than the nuclear one, restores incorporation of labelled putrescine into polyamines, enhances ornithine decarboxylase and S-adenosylmethionine decarboxylase activities and causes a 12-fold increase in cytoplasmic Mn2+-dependent polyadenylate polymerase activity. After treatment with noradrenaline the increase in radioactivity was found solely in AMP after hydrolysis of microsomal RNA to nucleoside monophosphates.


1975 ◽  
Vol 148 (3) ◽  
pp. 381-387 ◽  
Author(s):  
S Sen ◽  
P I Payne ◽  
D J Osborne

Incorporation studies with radioactive precursors showed that synthesis of protein and RNA is initiated in germinating embryos of rye within the first hour of imbibition of water. By polyacrylamide-gel fractionations of radioactive nucleic acid components, the appearance of products of transcription of the genome was shown to follow the sequence: heterogeneous (ribonuclease-sensitive) RNA, 4S and 5S RNA by 20min, 31S and 25S rRNA by 40min, and 18S RNA by 60min. “Fingerprint’ analysis of T1-ribonuclease digests show that all the large oligonucleotides present in 25S and 18S RNA are present in the 31S species, indicating that 31S RNA is the precursor rRNA molecule to both 25S and 18S RNA. The importance of these early RNA syntheses and in particular the possible template function of the heterogeneous RNA is discussed in relation to the concept of long-lived mRNA and the coding for protein synthesis in the first hours of germination.


1977 ◽  
Vol 168 (3) ◽  
pp. 333-340 ◽  
Author(s):  
A Casti ◽  
A Corti ◽  
N Reali ◽  
G Mezzetti ◽  
G Orlandini ◽  
...  

Noradrenaline added to perfused rabbit heart previously perfused with labelled precursors causes, after 2.5 and 5.0 min, a general increase of specific radioactivity or RNA in subcellular fractions, but no augmentation of acetylation of F2a2 and F2a1 histone fractions and no stimulation of DNA-dependent RNA polymerase activities. Synthesis of spermidine and spermine is enhanced at 10.0 min of treatment, when there is also a fall in specific radioactivity of RNA. The cytoplasmic Mn2+-stimulated polyadenylate polymerase activity is strongly enhanced 30s to 2.5 min after injection of noradrenaline or of dibutyryl cyclic AMP. Both the cyclic nucleotide and noradrenaline have no influence in vitro on the polyadenylate polymerase reaction.


1970 ◽  
Vol 245 (10) ◽  
pp. 2679-2692
Author(s):  
David A. Sirbasku ◽  
John M. Buchanan

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