Posttranslational phosphorylation of specific chromosomal proteins and transcription of hnRNA genes in isolated nuclei: Retention of <i>in vivo</i> sensitivity to 5,6‐dichloro‐1‐β‐D‐ribofuranosylbenzimidazole (DRB)

Holst, Mikael; Egyházi, E.

doi:10.1002/jcb.240290207

Cited by 13 publications

(2 citation statements)

References 23 publications

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“…ORB has been shown to inhibit reversibly the synthesis of heterogeneous nuclear RNA (hnRNA) in mammalian cells but, although it is now widely used as a tool for studying early events in transcription (Skolnik-David et al, 1982;Tweeten and Molloy, 1982;Mukherjee and Molloy, 1987;Barettino et al, 1988;Chaly et el., 1988;Gallinaro et el., 1988;Chodosh et el., 1989), its mechanism of action remains unclear (Zandomeni et al, 1983). Recently it has been proposed that the target of ORB inhibition could be casein kinase II (Zandomeni and Weinmann, 1984;Holst and Egyhazi, 1985;Zandomeni et el., 1986;Stevens and Maupin, 1989;Zandomeni, 1989;Meggio et aI., 1990;Dobrowolska et el., 1991), an enzyme involved in the regulation of mRNA transcription in eukaryotic systems via phosphorylation of subunits of RNA polymerase II and/or transcription factors (Horikoshi et ei., 1987;Paynet et al, 1989). Furthermore, it has been demonstrated that ORB is transported across the plasma membrane into cells by facilitated diffusion, and it is efficiently metabolized to its 2'-and 5'-monophosphates (Egyhazi et al, 1980).…”

Section: Introductionmentioning

confidence: 99%

Synthesis and Biological Evaluation of New 5,6-dichlorobenzimidazole Nucleoside Derivatives

Gosselin

Philouze

Bergogne

et al. 1994

Antivir Chem Chemother

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Novel 5,6-dichlorobenzimidazole nucleoside analogues structurally related to the well-known riboside DRB have been synthesized. The 1′,2′- trans nucleosides were prepared by condensation of peracylated sugars with 5,6-dichlorobenzimidazole, whereas the 1′,2′- cis β-D-arabinofuranosyl and β-D-lyxofuranosyl nucleosides were obtained by inversion of configuration on the sugar moiety. Chiral acyclic derivatives were stereospecifically prepared by ring-opening of furano- or pyrano-nucleosides by means of periodate oxidation, followed by borohydride reduction. The in vitro activities against a range of DNA and RNA viruses, as well as the cytotoxicities in human T-lymphocyte MT-4 cells, have been determined for these novel compounds and for DRB. No truly selective activity (i.e. clearly below the cytotoxic concentration) was observed against any of the viruses used. Some of the compounds, including DRB, were cytotoxic to MT-4 cells at CC50 values of less than 10 μg ml−1.

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Section: Introductionmentioning

confidence: 99%

Synthesis and Biological Evaluation of New 5,6-dichlorobenzimidazole Nucleoside Derivatives

Gosselin

Philouze

Bergogne

et al. 1994

Antivir Chem Chemother

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“…Secondly whether the phosphorylation level of nucleolin is physiologically significant and correlated with the rate of proliferation of the cells [6]. Since DRB is known to change the in vivo phosphorylation level of some polypeptides [7,19], we examined, using two cytochemical procedures (silver and bismuth staining), any notable modifications in the level of phosphorylation of the nucleolar proteins during DRB treatment. Our results demonstrate that the changes in the organization of the transcriptional components of the nucleolus observed after DRB treatment are radically different from those observed after the action of inhibitory drugs such as AMD.…”

Section: Introductionmentioning

confidence: 99%

The effect of adenosine analogue (DRB) on a major nucleolar phosphoprotein nucleolin

Noaillac-Depeyre¹,

Dupont²,

Tichadou³

et al. 1989

Biology of the Cell

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Nucleolin, a phosphorylated nucleolar protein, of 100 kDa selectively stained with bismuth tartrate and silver nitrate, is implicated in the transcription and maturation of pre-ribosomal RNA. Nucleolin also fulfills a structural function in nucleolar organization. Using immunocytochemistry the action of 5-6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB), an inhibitor of hn/RNA synthesis known to modify the organization of the nucleolus, was studied for its effects on the distribution and the amount of nucleolin present. After DRB treatment, the morphology of the nucleolus was rapidly disturbed, but the distribution of the nucleolin remained unchanged: the dense fibrillar and the granular components were always positively immunostained. Thirty min after incubation with the drug, a strong increase of the amount of nucleolin occurred. Prolonged treatment led to a marked loss of label. Silver and bismuth staining showed that DRB does not seem to significantly affect the phosphorylation of nucleolin.

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Selective repression of RNA polymerase II by Microinjected phosvitin

Egyházi

Pigon

1986

Chromosoma

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We have used a microinjection technique to examine whether injected phosvitin, in its capacity as substrate for casein kinase NII, could compete out the endogenous phosphorylation of some nuclear phosphoproteins with regulatory potential and thereby interfere with the activity of RNA polymerase II. Phosphorylation, which utilizes ATP as phosphate donor, was separated from phosphorylation which uses GTP. Phosvitin introduced into nuclei of salivary gland cells becomes phosphorylated by the endogenous nuclear protein kinase(s) and incorporates phosphates from ATP as well as from GTP. The phosphorylation of nuclear proteins and phosvitin is heparin-sensitive, indicating that they are phosphorylated by casein kinase NII. Microinjected phosvitin does not seem to affect the incorporation of phosphate groups from ATP into nuclear proteins, but protein phosphorylation by GTP is influenced. Apart from a minor overall reduction of 32P-incorporation, the phosphorylation of a 42 kDa nuclear protein, a putative transcription stimulatory factor, and of a 115 kDa nuclear protein was competed out by 70%-80% compared with the control value obtained in the absence of phosvitin. Parallel analyses of DNA transcription in phosvitin-injected nuclei showed that the RNA polymerase II-mediated synthesis of hnRNA and Balbiani ring RNA was diminished by 80% and 90%, respectively. In contrast, the transcription of nucleolar pre-ribosomal 38 S RNA by RNA polymerase I remained unaffected. The inhibitory effect of injected phosvitin could be reversed by in vitro phosphorylation of phosvitin prior to injection, using isolated nuclei as source of protein kinase(s). Taken together, the results suggest a causal relationship between the modification of the GTP-dependent phosphorylation of specific non-histone proteins and the activity of RNA polymerase II.

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Posttranslational phosphorylation of specific chromosomal proteins and transcription of hnRNA genes in isolated nuclei: Retention of in vivo sensitivity to 5,6‐dichloro‐1‐β‐D‐ribofuranosylbenzimidazole (DRB)

Cited by 13 publications

References 23 publications

Synthesis and Biological Evaluation of New 5,6-dichlorobenzimidazole Nucleoside Derivatives

Synthesis and Biological Evaluation of New 5,6-dichlorobenzimidazole Nucleoside Derivatives

The effect of adenosine analogue (DRB) on a major nucleolar phosphoprotein nucleolin

Selective repression of RNA polymerase II by Microinjected phosvitin

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