Evidence for transcriptional and post-transcriptional control of the cellular thymidine kinase gene.

Stewart, C; Ito, Moriko; Conrad, Susan E.

doi:10.1128/mcb.7.3.1156

Cited by 109 publications

(85 citation statements)

References 29 publications

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“…The RNA level increased beginning at 12 hr postinfection and reached a plateau at -2 0 hr postinfection, remaining constant for at least another 16 hr. In our hands, the change in Sp 1 was at least 2-fold greater than the stimulation of thymidine kinase mRNA, although thymidine kinase showed a 10-to 20-fold increase in other reports (Stuart et al 1985;Stewart et al 1987). The induction of Spl by viral infection was not simply due to stimulation of cell growth, because equal change was observed in logarithmically growing cells.…”

Section: Discussionmentioning

confidence: 54%

“…In addition to using equal amounts of total RNA from the infected and uninfected cells, we have used an internal negative control, [3-2 microglobulin, whose expression is unaffected by SV40 infection (Stuart et al 1985;Stewart et al 1987}. The level of [3-2 microglobulin mRNA remained constant over the course of the experiment (Fig.…”

Section: Sv40 Infection Stimulates Spl Expression At the M R N A Levelmentioning

confidence: 99%

“…As a positive control, we have probed the RNA from the infected cells for thymidine kinase mRNA, which is stimulated 10-to 20-fold by SV40 infection of confluent cells (Stuart et al 1985;Stewart et al 1987). We confirmed the SV40 induction of this message but observed only a fourfold increase in our experiments (Fig.…”

Section: Sv40 Infection Stimulates Spl Expression At the M R N A Levelmentioning

confidence: 99%

“…For example, T antigen stimulates cellular DNA synthesis (Chou and Martin 1975) and causes G~-arrested cells to enter S phase (Soprano et al 1979). The viral oncogene product also affects the steady-state levels of cellular RNA species (Shutzbank et al 1982) including thymidine kinase (Stuart et al 1985;Stewart et al 1987), and enhances rRNA synthesis by RNA polymerase I (Soprano et al 1979). To define specific events in the transformation process, it is important to understand the mechanisms by which T antigen induces these cellular regulatory changes.…”

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confidence: 99%

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SV40 stimulates expression of the transacting factor Sp1 at the mRNA level.

Saffer¹,

Jackson²,

Thurston³

1990

Genes Dev.

123

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Section: Discussionmentioning

confidence: 54%

Section: Sv40 Infection Stimulates Spl Expression At the M R N A Levelmentioning

confidence: 99%

Section: Sv40 Infection Stimulates Spl Expression At the M R N A Levelmentioning

confidence: 99%

mentioning

confidence: 99%

See 2 more Smart Citations

SV40 stimulates expression of the transacting factor Sp1 at the mRNA level.

Saffer¹,

Jackson²,

Thurston³

1990

Genes Dev.

123

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“…The induction of TK mRNA at this point during the cell cycle involves transcriptional (4,22,24,35), posttranscriptional (4,10,14,21,22,26,35) and translational (8,9,33) controls.…”

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confidence: 99%

Ordered splicing of thymidine kinase pre-mRNA during the S phase of the cell cycle.

1990

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Concomitant with the onset of S phase, a series of thymidine kinase (TK) splicing intermediates as well as mature TK mRNA accumulates in the nucleus of BALB/c 3T3 cells. Most of the TK splicing intermediates are retained by oligo(dT)-cellulose chromatography, and, therefore, 3' end formation and polyadenylation probably precede the splicing of TK pre-mRNAs. We have further characterized the TK pre-mRNAs that are present in the nuclei of S-phase cells by using specific probes derived from each of the six TK intervening sequences. Based on the sizes of the pre-mRNAs and their patterns of hybridization with these intron probes, we propose a pathway for intron removal from nascent TK transcripts. Intron excision occurred by a preferred, but not necessarily obligatory, order which appears to have been conserved in mouse and Chinese hamster cells.The cytosolic enzyme thymidine kinase (TK; ATP:thymidine 5'-phosphotransferase, EC 2.7.1.21) is of particular interest for the study of cell cycle-dependent regulatory mechanisms, because the mRNA encoding this enzyme accumulates to high levels just prior to the onset of S phase (12,15). The induction of TK mRNA at this point during the cell cycle involves transcriptional (4,22,24,35), posttranscriptional (4, 10, 14, 21, 22, 26, 35) and translational (8, 9, 33) controls.To obtain insight into the mechanism(s) involved in the posttranscriptional regulation of TK mRNA accumulation, we examined nuclear RNA from quiescent BALB/c 3T3 cells that had been restimulated to proliferate by the addition of fresh serum. Very little TK mRNA was detected in the nuclei of cells harvested during Go and Gl. At the onset of S phase, however, we observed a dramatic change in the processing of TK mRNA precursors (pre-mRNA) that was characterized by the appearance of a series of high-molecular-weight TK mRNA precursors in addition to mature TK mRNA. These high-molecular-weight TK mRNAs could be chased in the presence of the RNA synthesis inhibitor dactinomycin, suggesting a precursor-product relationship (11).We proposed that the high-molecular-weight TK transcripts were splicing intermediates which retained various intervening sequences (IVSs). Most eucaryotic genes contain IVSs or introns that are excised from nuclear premRNA by the RNA splicing machinery (1,25,27,32). To gain insight into the nature of the putative high-molecularweight TK pre-mRNAs present in G,/S-and S-phase nuclei, as well as to determine whether there is a preferential order of IVS removal from the TK gene, we further characterized the TK pre-mRNA splicing intermediates present in S-phase cells by Northern (RNA) blot analysis.Mammalian TK genes, which contain seven coding exons and six introns, have been well conserved during evolution (6,20,23,31). We isolated unique sequence DNA probes from each of the six TK introns and used them to character-* Corresponding author.ize the splicing intermediates in the nuclei. The human TK gene has the highest density of Alu-like repetitive elements within its intervening sequences of an...

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A new class of reversible cell cycle inhibitors

et al. 1991

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The effects of three compounds on the cell cycle of HL-60 promyeloid leukemia cells has been examined. Ciclopirox olamine, an antifungal agent, and the compound Hoechst 768159 reversibly block the cell cycle at a point occurring roughly 1 h before the arrest mediated by aphidicolin, an inhibitor of DNA polymerase OL activity, which acts in early S phase. Similar results are also obtained with the compound mimosine, a plant amino acid. Based on these data, it is concluded that all three agents inhibit cell cycle traverse at or very near the GUS phase boundary and identify a previously undefined reversible cell cycle arrest point. Key terms: Flow cytometry, G1 phase block, mimosine, ciclopirox olamineThe elucidation of the biochemical events that regulate the induction of DNA synthesis in mammalian cells is of fundamental importance to an understanding of cellular growth control. In particular, the transcriptional and posttranscriptional events that control the G1 to S phase transition have been the subject of intensive research in recent years. It has been demonstrated that the expression of a number of genes required for DNA synthesis increases in the late G1 or early S phase. These include thymidine kinase (6,28), dihydrofolate reductase (121, and DNA polymerase a (33). In addition, the posttranslational modification of several proteins occurs prior to or at the GUS border. The phosphorylation of the 34 kDa protein (p34) encoded by the mammalian cdc2 gene occurs in late Gli early S phase in serum-stimulated mouse 3T3 fibroblasts (20,23). A change in the phosphorylation state of the product of the retinoblastoma susceptibility locus, which may also be important in cell cycle progression, also occurs near the GUS boundary (2,4,9,22).Compounds that perturb the cell cycle a t or near the GUS phase boundary will be essential in determining the role of these different biochemical events in the induction cells of DNA synthesis. The resolution of physical techniques such as cell sorting and centrifugal elutriation is not sufficient to subdivide adequately the late Gliearly S phase on the basis of DNA content or cell volume and density. Although a number of agents have been described that reversibly block cell cycle progression, most of these act in S phase. These include aphidicolin (APH), which blocks DNA polymerase c1 activity (13); 5-fluorodeoxyuridine, which inhibits thymidylate synthase (15); and hydroxyurea, which acts on ribonucleotide reductase (27). Of these S phasespecific inhibitors, APH has been shown to act earliest in S phase (29). APH inhibits DNA replication by interfering with the binding of deoxynucleotide triphosphates to DNA polymerase (13). Both molecular and kinetic (1,7,10,11,21,26,29,31,34) studies indicate that APH blocks cell cycle progression in S phase cells that are undergoing active DNA replication and prevents the entry of cells into S phase just beyond the GliS border. The cloning and characterization of the eukaryotic chromosomal replication origins, which are DNA sequences associated w...

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Evidence for transcriptional and post-transcriptional control of the cellular thymidine kinase gene.

Cited by 109 publications

References 29 publications

SV40 stimulates expression of the transacting factor Sp1 at the mRNA level.

SV40 stimulates expression of the transacting factor Sp1 at the mRNA level.

Ordered splicing of thymidine kinase pre-mRNA during the S phase of the cell cycle.

A new class of reversible cell cycle inhibitors

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