Intranuclear maturation pathways of rat liver ribosomal ribonucleic acids

Dabeva, Mariana D.; Dudov, K P; Hadjiolov, A.A.; Emanuilov, I; Todorov, B.

doi:10.1042/bj1600495

Cited by 44 publications

(32 citation statements)

References 27 publications

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“…The proposed explanation of our experimental findings is based on the assumption that the specification of endonuclease-attack sites 1-4 is a stable characteristic of the 45-S pre-rRNA particle. The observed discrete intermediate pre-rRNA peaks and their molecular weights are in line with such an assumption (see [2,18,23]). However, analysis of terminal sequences in all intermediate pre-rRNA components is needed before the proposed tentative scheme of 45-S pre-rRNA processing can be ascertained.…”

Section: Discussionsupporting

confidence: 60%

“…the pattern of nucleolar RNA is altered already at 30 -60 min after cycloheximide administration. The peaks of 41-S and 21-S pre-rRNA are reduced to background, while the peak of 39-S prerRNA [16,23] becomes more and more prominent. Accumulation of 260-nm absorbing material in 36-S and 32-S pre-rRNA also takes place making the peaks of these two pre-rRNA species prominent.…”

Section: Processing O J Rrna Precursors Upon Inhibition Of Protein Symentioning

confidence: 96%

“…As can be seen, the A260 [16]. Upon 15-min labelling with [14C]orotate in vivo, the bulk of the label is in 45-S pre-rRNA, but some labelling of 41-S, 36-S and 32-S pre-rRNA also takes place [23].…”

Section: Processing O J Rrna Precursors Upon Inhibition Of Protein Symentioning

confidence: 98%

“…The early appearance of a prominent 39-S pre-rRNA peak is of particular interest. We have shown earlier that it may originate from a low-probability direct endonuclease split of 45-S prerRNA at site 4 [18,23]. Hydrolysis at site 4 generates 39-S and '28-S' RNA components, which are unlikely to be processed further and may be considered as aberrant products destined for degradation.…”

Section: Discussionmentioning

confidence: 99%

“…The homogenate was filtered through four layers of gauze and centrifuged for 10 min at 2000 x g The crude nuclear pellet was rehomogenized with two strokes of the pestle in 2.3 M sucrose in the same buffer and processed further to isolate pure liver nuclei as described [15]. The post-nuclear supernatant was diluted with an equal volume of 0.25 M sucrose, 0.1 M Tris-HC1 (pH 7.6), 0.05 M KCl and centrifuged for 15 min at 17000 x g to sediment mitochondria and lysosomes.…”

Section: Cell Fractionationmentioning

confidence: 99%

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Alterations in the Processing of Rat-Liver Ribosomal RNA Caused by Cycloheximide Inhibition of Protein Synthesis

Stoyanova¹,

Hadjiolov²

1979

European Journal of Biochemistry

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Cycloheximide given in vivo at low doses (2 -5 mg/kg body weight) causes within 30 min a complete inhibition of protein synthesis in rat liver. The labelling of nuclear proteins is also strongly inhibited. Under these conditions, the amount of nucleolar 45-S pre-rRNA and its ['"CIorotate labelling remain unaffected for at least 4 h. These results show that initially the rates of synthesis and processing of 45-S pre-rRNA are not appreciably altered. On the other hand, drastic alterations in the 45-S pre-rRNA processing pathways occur at the early stages of cycloheximide action. Formation of 18-S rRNA is abolished and that of 28-S rRNA is reduced to about half the level in control rats. This dichotomy in the production of the two ribosomal particles may be correlated with a block in the formation of 41-S and 21-S pre-rRNA. Generation of 36-S and 32-S pre-rRNA is still taking place, but the rate of their processing to nucleolar 28-S rRNA is decreased, thus causing the accumulation of these two pre-rRNA species. In parallel, processing of 45-S prerRNA to an aberrant 39-S rRNA species is markedly enhanced. The results obtained show that the channelling of nucleolar pre-rRNA along alternative processing pathways is under stringent control by the continuous supply of critical protein(s).The formation of ribosomes in animal cells is dependent on the continuous supply of proteins. However, the critical sites in the pathway leading to mature ribosomes, affected primarily by the lack of control structural or regulatory protein(s), are not yet identified [1,2]. Experiments with HeLa cells [3] and rat liver in vivo [4] showed that cycloheximide block of protein synthesis results in a rapid inhibition of 45-S pre-rRNA synthesis. This early inhibition of transcription of rRNA genes appears to be due to an altered interaction of RNA polymerase A with nucleolar template chromatin [5,6]. The shortage of some control protein(s), characterized by a rapid turnover, has been implicated to explain the observed alterations in transcription [5-81. On the other hand, it was reported that block of protein synthesis by low doses of cycloheximide does not alter the synthesis of total nuclear RNA in rat liver [9]. Therefore, the inhibition of transcription, observed with high doses of cycloheximide, could be due to some side effect of the drug or its metabolites rather than to the shortage of putative control proteins (see [2]).Inhibition of 45-S pre-rRNA processing and formation of mature ribosomes upon cycloheximide block of protein synthesis was observed with HeLa [3,10] and L [ l l , 121 cells, regenerating rat liver [13] and culAbbreviations. pre-rRNA, precursor to rRNA; hnRNA, heterogeneous nuclear RNA. tured lymphocytes [14]. The exact mechanisms of this inhibition of ribosome formation and its possible dependence on simultaneous alterations of transcription remain unclear (see [1,2]).In this work we studied the action of cycloheximide in vivo on 45-S pre-rRNA synthesis and processing in rat liver. It is shown that low doses of cycl...

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Section: Discussionsupporting

confidence: 60%

Section: Processing O J Rrna Precursors Upon Inhibition Of Protein Symentioning

confidence: 96%

Section: Processing O J Rrna Precursors Upon Inhibition Of Protein Symentioning

confidence: 98%

Section: Discussionmentioning

confidence: 99%

Section: Cell Fractionationmentioning

confidence: 99%

See 3 more Smart Citations

Alterations in the Processing of Rat-Liver Ribosomal RNA Caused by Cycloheximide Inhibition of Protein Synthesis

Stoyanova¹,

Hadjiolov²

1979

European Journal of Biochemistry

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In vivo disruption of Xenopus U3 snRNA affects ribosomal RNA processing.

1990

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DNA oligonucleotide complementary to sequences in the 5′ third of U3 snRNA were injected into Xenopus oocyte nuclei to disrupt endogenous U3 snRNA. The effect of this treatment on rRNA processing was examined. We found that some toads have a single rRNA processing pathway, whereas in other toads, two rRNA processing pathways can coexist in a single oocyte. U3 snRNA disruption in toads with the single rRNA processing pathway caused a reduction in 20S and ‘32S’ pre‐rRNA. In addition, in toads with two rRNA processing pathways, an increase in ‘36S’ pre‐rRNA of the second pathway is observed. This is the first in vivo demonstration that U3 snRNA plays a role in rRNA processing. Cleavage site #3 is at the boundary of ITS 1 and 5.8S and links all of the affected rRNA intermediates: 20S and ‘32S’ are the products of site #3 cleavage in the first pathway and ‘36S’ is the substrate for cleavage at site #3 in the second pathway. We postulate that U3 snRNP folds pre‐rRNA into a conformation dictating correct cleavage at processing site #3.

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Biogenesis of Ribosomes in Eukaryotes

Hadjiolov

1980

Subcellular Biochemistry

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Intranuclear maturation pathways of rat liver ribosomal ribonucleic acids

Cited by 44 publications

References 27 publications

Alterations in the Processing of Rat-Liver Ribosomal RNA Caused by Cycloheximide Inhibition of Protein Synthesis

Alterations in the Processing of Rat-Liver Ribosomal RNA Caused by Cycloheximide Inhibition of Protein Synthesis

In vivo disruption of Xenopus U3 snRNA affects ribosomal RNA processing.

Biogenesis of Ribosomes in Eukaryotes

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