Individual<i>Xenopus</i>histone genes are replication-independent in oocytes and replication-dependent in<i>Xenopus</i>or mouse somatic cells

Old, Robert; Sheikh, Semira; Chambers, A.; Newton, C.A.; Mohammed, A.; Aldridge, T.C.

doi:10.1093/nar/13.20.7341

Cited by 17 publications

(8 citation statements)

References 32 publications

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“…The histone H2A and H2B genes in this cluster are transcribed in opposite directions from initiation sites located approximately 235 bp apart. This arrangement of H2A and H2B genes is not unique; it is also found in the genomes of unicellular organisms and other vertebrates (18,21,26,29,38). Histone H2A and H2B genes are often paired and transcribed in opposite directions, even in the genomes of organisms whose histone genes are not generally clustered (26,30).…”

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confidence: 87%

“…Transcription ceases upon oocyte maturation and resumes after the midblastula transition, when transcription of zygotic genes begins. Histone gene transcription is DNA replication dependent in most cells of postmidblastula transition embryos and adult frogs (29,35,40). The mechanisms underlying this change in histone gene transcriptional regulation, from constitutive or basal expression in oocytes to S-phase-specific expression in embryos, are not understood.…”

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confidence: 99%

“…Many organisms have distinct sets of histone genes that are transcribed independently of DNA replication (for example, mouse testisspecific histone genes [21]). In Xenopus laevis, the same histone genes are transcribed in both DNA replication-dependent and replication-independent modes (29,34). Histone genes are transcribed in the absence of DNA replication in oocytes which are arrested in the G 2 phase of the first meiotic division.…”

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Interaction of the CCAAT Displacement Protein with Shared Regulatory Elements Required for Transcription of Paired Histone Genes

El‐Hodiri

Perry

1995

Molecular and Cellular Biology

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The H2A and H2B genes of the Xenopus xlh3 histone gene cluster are transcribed in opposite directions from initiation points located approximately 235 bp apart. The close proximity of these genes to one another suggests that their expression may be controlled by either a single bidirectional promoter or by separate promoters. Our analysis of the transcription of histone gene pairs containing deletions and site-specific mutations of intergenic DNA revealed that both promoters are distinct but that they overlap physically and share multiple regulatory elements, providing a possible basis for the coordinate regulation of their in vivo activities. Using the intergenic DNA fragment as a probe and extracts from mammalian and amphibian cells, we observed the formation of a specific complex containing the CCAAT displacement protein (CDP). The formation of the CDP-containing complex was not strictly dependent on any single element in the intergenic region but instead required the presence of at least two of the three CCAAT motifs. Interestingly, similar CDP-containing complexes were formed on the promoters from the three other histone genes. The binding of CDP to histone gene promoters may contribute to the coordination of their activities during the cell cycle and early development.Histone genes are ubiquitously expressed in eukaryotic cells, usually in a cell cycle-specific manner, resulting in the accumulation of equimolar amounts of the nucleosome core histones H2A, H2B, H3, and H4. In most cell types, histone protein and RNA synthesis are primarily restricted to the S phase of the cell cycle and require ongoing DNA synthesis (for reviews, see references 17, 18, 26, and 30). Histone gene expression is regulated by both transcriptional and posttranscriptional mechanisms. In cycling cells, transcription of members of each of the five histone gene classes is coordinately activated upon entry into S phase and is then extinguished at the end of the DNA replication period. Histone gene promoters have no obvious transcription factor-binding motifs in common, aside from TATA and CCAAT motifs, leading to the idea that coordinate histone gene transcription is not regulated through the action of a single, common cis-acting element (17, 30). Regulatory elements and trans-acting factors responsible for basal transcription and S-phase-specific transcription of human H1, H2B, and H4 genes have been identified. An H1 subtypespecific element and a CCAAT motif required for S phasespecific transcription of the H1 promoter interact with distinct factors (13). Activation of H2B and H4 gene transcription during S phase is thought to require the interaction of positiveacting factors with H2B and H4 subtype-specific cis-acting elements (reviewed in reference 17).Histone gene transcription is usually restricted to S phase of the cell cycle, although examples of non-cell cycle-regulated expression of histone gene subclasses are known. Many organisms have distinct sets of histone genes that are transcribed independently of DNA replication (for...

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Interaction of the CCAAT Displacement Protein with Shared Regulatory Elements Required for Transcription of Paired Histone Genes

El‐Hodiri

Perry

1995

Molecular and Cellular Biology

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“…In Xenopus cells, histone genes are actively transcribed during oogenesis, inactivated when the germinal vesicle breaks down during oocyte maturation, and then reactivated in blastula-stage embryos after fertilization. Because the same histone gene sets are replication independent in oocytes and replication dependent in somatic cells and embryos (37,42), it appears that Xenopus histone gene expression undergoes a transition from constitutive or basal activity during oogenesis to cell cycle-regulated expression later in development by a mechanism that is not well understood.…”

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Histone H2B gene transcription during Xenopus early development requires functional cooperation between proteins bound to the CCAAT and octamer motifs.

Hinkley¹,

Perry²

1992

Mol. Cell. Biol.

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The ubiquitously expressed transcription factor Oct-I and several other members of the POU domain protein family bind to a site, termed the octamer motif, that functions in the promoter and enhancer regions of a variety of genes expressed under diverse conditions. An octamer motif present in a conserved histone H2B-specific promoter element is required for S-phase-specific transcription of mammalian histone H2B genes in cultured cells. We have previously shown that the octamer motif in a Xenopus histone H2B gene promoter was inactive in nondividing frog oocytes. Here we show that the octamer motif, in addition to regulatory elements (TATAA, CCAAT, and ATF motifs) that are active in oocytes, is required for maximal H2B gene transcription in developing frog embryos. Factors binding to each of the H2B upstream promoter elements are present in oocytes and increase slightly in abundance during early development. The activity of the H2B octamer motif in embryos is not specifically associated with increased binding by Oct-I or the appearance of novel octamerbinding proteins but requires the presence of an intact CCAAT motif. Our results indicate that synergistic interactions among promoter-bound factors are important for octamer-dependent H2B transcription. We suggest that the activity of the H2B promoter is regulated primarily by changes in the interactions between proteins already bound to the promoter rather than by alterations in their intrinsic abilities to bind DNA.

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“…An examination of histone mRNA accumulation has demonstrated that transcripts from genes in both types of clusters are present throughout oogenesis and embryogenesis (32). Analysis of the expression of cloned X. laevis histone genes in cultured X. laevis cells, transfected mouse cells, and frog oocytes has demonstrated that their transcription is replication dependent in somatic cells and replication independent in oocytes (28). The conclusions that have emerged from these and related studies (40) are that no major developmental changes occur in the types of histone genes active during embryogenesis, but that their regulation undergoes a transition from constitutive expression during oogenesis to cell cycle-regulated expression at some point in embryogenesis.…”

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Promoter sequences required for transcription of Xenopus laevis histone genes in injected frog oocyte nuclei.

Heindl¹,

Weil²,

Perry³

1988

Mol. Cell. Biol.

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Amphibian oogenesis is accompanied by the accumulation of histone mRNA and proteins in the absence of ongoing DNA replication. To begin an analysis of the mechanisms by which histone gene expression is regulated during frog oogenesis and embryogenesis, we used oocyte injection to examine the upstream sequences required for transcription of genes encoding each of the five histone classes. We found that sequences necessary for maximal levels of transcription are located 100 to 200 base pairs upstream of the corresponding start sites. In this region, each promoter examined contains conserved sequence elements, several of which seem to be histone gene class specific, in addition to other, more common sequence elements believed to be used by general transcription factors.

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IndividualXenopushistone genes are replication-independent in oocytes and replication-dependent inXenopusor mouse somatic cells

Cited by 17 publications

References 32 publications

Interaction of the CCAAT Displacement Protein with Shared Regulatory Elements Required for Transcription of Paired Histone Genes

Interaction of the CCAAT Displacement Protein with Shared Regulatory Elements Required for Transcription of Paired Histone Genes

Histone H2B gene transcription during Xenopus early development requires functional cooperation between proteins bound to the CCAAT and octamer motifs.

Promoter sequences required for transcription of Xenopus laevis histone genes in injected frog oocyte nuclei.

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