Association of transcriptionally active vitellogenin II gene with the nuclear matrix of chicken liver.

Jost, Jean-Pierre; Seldran, Monique

doi:10.1002/j.1460-2075.1984.tb02082.x

Cited by 62 publications

(19 citation statements)

References 35 publications

(20 reference statements)

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“…Recently, specific adenine-plus-thymine-rich nucleotide sequences between the Hi and H3 genes in the repeating histone gene units of Drosophila were found to be associated with the nuclear scaffold (28). This is a particularly interesting observation in view of other results which indicate that transcriptionally active P-globin (20), ovalbumin (6,36), and vitellogenin II (21) genes are always associated with the nuclear matrix. Furthermore, fixed sites of DNA replication have been proposed which involve DNA replication complexes being anchored to the matrix.…”

Section: Discussionmentioning

confidence: 76%

Transcription of the histone H5 gene is not S-phase regulated.

Dalton¹,

Coleman²,

Wells³

1986

Mol. Cell. Biol.

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Levels of the tissue-specific linker histone H5 are elevated in mgture erythroid cells as compared with levels in dividing cells of the same lineage. We examined levels of H5 mRNA in relation to the cell cycle in early erythroid cells transformed by avian erythroblastosis virus to determine whether the gene for this unusual histone is S-phase regulated. Northern blotting analyses revealed that during the cell cycle steady-state levels of H5 mRNA remained relatively constant in contrast to levels of the major core and Hl mRNAs which increased approximately 15-fold during S phase. In vitro pulse-labeling experiments involving nuclei isolated from synchronized cells at various stages of the cell cycle revealed that transcription of the H5 gene was not initiated at any particular stage of the cell cycle but was constitutive. In contrast, transcription of the H2A gene(s) initiated in early S phase, was present throughout the DNA replicative phase, and was essentially absent in Gl and G2 phases.The H5 histone gene is unusual in several ways. It is a single-copy gene which is not closely linked to the clustered core and Hi genes in the chicken genome (23). It is expressed only in cells of the erythroid lineage (27,29), and its mRNA is polyadenylated (22). H5 proteins gradually replace Hi histones during maturation of erythroid cells, although fully mature erythrocytes still contain significant levels of Hi proteins. In this work we investigated the regulation of H5 gene transcription in relation to other chicken histone genes during the cell cycle.A large body of evidence indicates that synthesis of core and Hi histones is coincident with DNA synthesis during the cell cycle (11, 35), although Groppi and Coffino (17) showed that histone synthesis in S49 mouse lymphoma cells can also occur in Gi. Nevertheless, the general consensus is that histone protein synthesis is temporally coupled to DNA replication to facilitate the coordinated assembly of nucleosomes.The controlling factors governing histone protein levels in eucaryotic cells are not clearly understood. The molecular cloning of histone genes from a range of eucaryotes has made experiments investigating the content and metabolism of the major histone (Hi, H2A, H2B, H3, and H4) mRNA species possible. Studies with synchronous populations of tissue culture cells obtained by treatment with aphidicolin (19) or hydroxyurea (38), serum deprivation (9), use of cell-cycle mutants (2), and centrifugal elutriation (1) have shown that levels of the major histone mRNA species increase by approximately 10-to 20-fold during S phase. Furthermore, treatment of synchronized cells in S phase with inhibitors of DNA synthesis rapidly reduces levels of the major histone mRNAs (3, 16, 34), indicating a coupling between histone gene expression and DNA replication. Further data indicate that elevated histone mRNA levels in S phase result from an increased rate of transcription and increased mRNA stability (1,19,38).We show in this study that these parameters are not valid for the histone...

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Section: Discussionmentioning

confidence: 76%

Transcription of the histone H5 gene is not S-phase regulated.

Dalton¹,

Coleman²,

Wells³

1986

Mol. Cell. Biol.

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“…Indirect support for this model is offered by a number of studies that document an association between actively transcribed genes and the nuclear matrix (1,18,20,23,36). That transcription might lead to unequal plasmid partition is also suggested by the unusually high stabilities of certain plasmids that have neither the REP stabilization system nor centromeric sequences.…”

Section: Resultsmentioning

confidence: 92%

Copy number and partition of the Saccharomyces cerevisiae 2 micron plasmid controlled by transcription regulators.

Veit¹,

Fangman²

1988

Mol. Cell. Biol.

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The 2,m plasmid of Saccharomyces cerevisiae is maintained by the action of plasmid-encoded gene products that control copy number and promote equipartition of plasmid copies at cell division. We show that the REP) and REP2 plasmid-encoded gene products are master regulators that act in concert to autoregulate the level of their own transcripts and to regulate transcript levels of the FLP gene that promotes plasmid copy amplification. REP) and REP2 are also shown to repress transcription at REP3, the cis-acting site essential for plasmid equipartitioning. We propose a model in which REP3 acts by dislodging transcription apparatuses that otherwise cause plasmid molecules to adhere to the mother nucleus and segregate asymmetrically. On the basis of their ability to generate specific chromatin structures, we also propose that the REP] and REP2 gene products interact with different specific sequences found iterated in the 2ILm plasmid.The 2,m plasmid is a 6.3-kilobase (kb) multicopy circular DNA found in most strains of S. cerevisiae (2,3,12,30). Because the plasmid confers no selective advantage to its host, it must rely on an efficient maintenance system. The rate at which cells lacking 2,um (ciro cells) are generated, approximately 10-4 to 10-5 per cell per generation (13), indicates an aggregate stability comparable with that of individual chromosomes (16). The chromosomally encoded nuclear replication apparatus contributes to plasmid maintenance. Mutations or inhibitors that block chromosomal replication similarly affect the 2,m plasmid (26). Like chromosomes, each of the 50 to 100 copies of the 2ixm plasmid replicates once during S phase (46). Once replicated, however, plasmid and chromosomal DNAs appear to be partitioned within the dividing nucleus by distinct mechanisms. Whereas the partition of chromosomes is mediated by centromeric sequences (10), the 2,um plasmid relies on an apparently unrelated cis-acting element, REP3. As defined by its ability to enhance the stability of chimeric derivatives of the 2,m plasmid, REP3 function requires at least two of five 62-base-pair (bp) tandemly repeated sequences (21,22). This locus appears to correspond to the STB locus (24) for which sequences flanking the 62-bp repeats were also found necessary for stabilization. Recent work suggests that flanking sequences may enhance REP3 function by preventing transcription through the direct repeats (32).The stabilization of the 2,um plasmid by REP3 requires two trans-acting plasmid genes, REP] and REP2 (5,21,24,43 (46). Moreover, the REP system is able to stabilize plasmids in the absence of FLP-catalyzed recombination. It therefore seems that the REP3-mediated stabilization reflects a more equal distribution of plasmid copies at division rather than correction of an initially biased distribution.In a previous study (43) In this study, we have used two approaches to document the negative regulation of FLP and other plasmid gene transcript levels by REP gene products. We first describe increases in transcript levels that res...

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“…At the same time there is a binding of the 5' and 3' end flanking region of the gene to the nuclear matrix (5) and the appearance of DNAse I hypersensitive sites in the promoter region (6, 7) (see Fig. 1).…”

Section: Introductionmentioning

confidence: 99%