Nucleosomes inhibit both transcriptional initiation and elongation by RNA polymerase III in vitro.

Morse, Randall H.

doi:10.1002/j.1460-2075.1989.tb08362.x

Cited by 106 publications

(72 citation statements)

References 44 publications

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“…Such partial protection against cleavage might be expected given that, although nucleosomal DNA is resistant to restriction (1,2,46,50,84), nucleosomes in this region of the LTR are not uniquely positioned (26). In general, the accessibility at most of the sites examined in the MMTV promoter was inversely correlated with our rough estimate of the nucleosome frame occupancy, e.g., HaeIII at Ϫ225, SacI at Ϫ109, and AflII at Ϫ201.…”

Section: Discussionmentioning

confidence: 57%

The Position and Length of the Steroid-Dependent Hypersensitive Region in the Mouse Mammary Tumor Virus Long Terminal Repeat Are Invariant despite Multiple Nucleosome B Frames

Fragoso

Pennie

John

et al. 1998

Molecular and Cellular Biology

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Stimulation of the mouse mammary tumor virus with steroids results in the generation of a DNase I-hypersensitive region (HSR) spanning the hormone responsive element (HRE) in the long terminal repeat. Restriction enzymes were used to characterize the accessibility of various sites within the HSR of mouse mammary tumor virus long terminal repeat-reporter constructions in four different cell lines. The glucocorticoid-dependent HSR was found to span minimally 187 bases, a stretch of DNA longer than that associated with histones in the core particle. Although the 5-most receptor binding site within the HRE is downstream of ؊190, hypersensitive sites were found further upstream to at least ؊295. The relationship in the accessibility between pairs of sites in the vicinity of the HSR was further examined in one cell line by a two-enzyme restriction access assay. In the uninduced state, the accessibilities at these sites were found to be independent of each other. In contrast, when stimulated with hormone, the accessibilities at these sites were observed to become linked. That is, once a distinct promoter was activated, all of the sites within the HSR of that molecule became accessible. The HSR formed along an invariant stretch of DNA sequence despite the multiplicity of nucleosome frames in the nucleosome B region, where the HRE is located. The results indicate that the macroscopic length of the HSR does not arise from core length-remodeling events in molecules containing Nuc-B in alternative positions.Regulation of transcription of the mouse mammary tumor virus (MMTV) by steroid hormones is mediated through a hormone response element (HRE) located between positions Ϫ70 and Ϫ190 (16,28,33,39). Four binding sites for steroid receptors have been mapped within the HRE (57,61,68,82). Binding sites for other factors have also been detected within (30,41,73,74) and immediately upstream of (17,27,44,45,49) this region, and they participate in the regulation of MMTV by steroids (17,27,44,45,74). Loading of transcription factors downstream of the HRE occurs upon activation of the promoter by the glucocorticoid or the progesterone receptors, including NF-1, and TFIID (5,19,43,59,76). Concomitant with this activation, hypersensitivity to DNase I, methidiumpropyl-EDTA ⅐ iron(II) [MPE-Fe(II)], and restriction enzymes is detected in the general location of the HRE (3, 9, 62, 67, 76, 88).To understand the chromatin transition leading to hypersensitivity and thus the regulation of MMTV by steroids, it is necessary to understand the chromatin organization of the promoter in both the uninduced and induced states. The long terminal repeat (LTR) of MMTV is organized in an array of six nucleosomes termed Nuc-A through Nuc-F; the HRE and the transcription initiation site are in the Nuc-B and Nuc-A regions, respectively (67). Nucleosomes in these two regions of the LTR occupy multiple frames; that is, different copies of the LTR possess Nuc-A and Nuc-B in different positions (26). Although treatment with dexamethasone, a synthetic glucocort...

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Section: Discussionmentioning

confidence: 57%

The Position and Length of the Steroid-Dependent Hypersensitive Region in the Mouse Mammary Tumor Virus Long Terminal Repeat Are Invariant despite Multiple Nucleosome B Frames

Fragoso

Pennie

John

et al. 1998

Molecular and Cellular Biology

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“…However, elongation was more efficient on templates where the transcribed region contained only one to four nucleosomes (Felts et al 1990}. Morse utilized restriction enzyme digestion of minimally reconstituted chromatin templates to show directly that the elongation potential of RNA polymerase III is inhibited by a single nucleosome via a "premature termination" mechanism (Morse 1989}. In contrast to the eukaryotic RNA polymerases, bacteriophage RNA polymerases will efficiently elongate on nucleosomal templates (Lorch et al 1987;Losa and Brown 1987;Morse 1989;Pfaffle et al 1990}. The reasons for this difference are not clear, but it is worth noting that bacteriophage RNA polymerases are capable of multiple rounds of initiation per template.…”

Section: Discussionmentioning

confidence: 99%

“…Studies with model systems using bacteriophage RNA polymerases and reconstituted templates indicate that nucleosomes need not be insurmountable barriers to RNA synthesis. These single-subunit RNA polymerases can efficiently elongate on both short fragments bearing one or two nucleosomes (Lorch et al 1987;Losa and Brown 1987;Morse 1989) and on templates with extended arrays of nucleosomes (Pfaffle et al 1990). RNA polymerase II will efficiently traverse a single nucleosome (Lorch et al 1987), but the effect of long nucleosomal arrays on polymerase II elongation has not been established.…”

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confidence: 99%

Transcription on nucleosomal templates by RNA polymerase II in vitro: inhibition of elongation with enhancement of sequence-specific pausing.

Izban¹,

Luse²

1991

Genes Dev.

236

215

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The process by which RNA polymerase II elongates RNA chains in vivo, where the template is at least partially in a nucleosomal configuration, remains poorly understood. To approach this question we have partially purified RNA polymerase lI transcription complexes paused early in elongation. These complexes were then used as substrates for chromatin reconstitution. Elongation of the nascent RNA chains on these nucleosomal templates is severely inhibited relative to elongation on naked DNA templates. Elongation on the nucleosomal templates results in a reproducible template-specific pattern of transcripts generated by RNA polymerase pausing. The RNA polymerases are not terminated because the large majority will resume elongation upon the addition of Sarkosyl or 400 mM KCI. The effectiveness of RNA polymerase II pause/termination sites is enhanced by the presence of nucleosomes. For example, a pause site similar in sequence to the c-myc gene exon 1 terminator is used four to seven times more effectively in reconstituted templates. A comparison of elongation on templates bearing phased nucleosomes and on reconstituted templates that show no predominant phasing pattern indicates that the locations of pause sites are not related to the positions of the nucleosomes. Rather, the major determinant of RNA polymerase pausing on the nucleosomal templates appears to be the underlying DNA sequence.[Key Words: RNA polymerase II; nucleosome; chromatin] Received November 8, 1990; revised version accepted February 5, 1991.A number of studies have indicated that transcriptionally active regions may continue to be packaged in nucleosomes while transcription occurs (Nacheva et al. 1989;Chen et al. 1990;Ericsson et al. 1990;Pederson and Morse 1990). This raises the question of how RNA polymerase II can effectively elongate RNA chains on these nucleoprotein templates. Studies with model systems using bacteriophage RNA polymerases and reconstituted templates indicate that nucleosomes need not be insurmountable barriers to RNA synthesis. These single-subunit RNA polymerases can efficiently elongate on both short fragments bearing one or two nucleosomes (Lorch et al. 1987;Losa and Brown 1987;Morse 1989) and on templates with extended arrays of nucleosomes (Pfaffle et al. 1990). RNA polymerase II will efficiently traverse a single nucleosome (Lorch et al. 1987), but the effect of long nucleosomal arrays on polymerase II elongation has not been established.The necessity for approaching this question biochem-ically has been emphasized by the growing realization that control of elongation by RNA polymerase II is an important aspect of gene regulation. Premature termination or pausing by RNA polymerase II has been observed in vivo for a number of genes, such as the proto-oncogenes c-myc and c-myb, the adenosine deaminase gene, and the hsp70 gene of Drosophila melanogaster (for review, see Spencer and Groudine 1990 and references therein). In vitro systems have been employed that reproduce some of the transcriptional pausing/termination events...

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“…Thus nucleosomes must be disrupted over the TATA box in order for the basal transcriptional machinery to function effectively. Even once the basal transcriptional machinery has gained access to DNA and recruited RNA polymerase, the elongation of the polymerase can be impeded by chromatin (Morse 1989, Hansen & Wolffe 1992. Both histone acetylation and the activity of SWI/SNF chromatin remodeling complexes can facilitate the processivity of RNA polymerase through chromatin (Brown et al 1996, Ura et al 1997.…”

Section: Chromatin and Transcription Factor Access To Dnamentioning

confidence: 99%

Nuclear receptors: coactivators, corepressors and chromatin remodeling in the control of transcription

Collingwood¹,

Fd²,

Ap³

1999

Journal of Molecular Endocrinology

295

172

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A contemporary view of hormone action at the transcriptional level requires knowledge of the transcription factors including the hormone receptor that may bind to promoters or enhancers, together with the chromosomal context within which these regulatory proteins function. Nuclear receptors provide the best examples of transcriptional control through the targeted recruitment of large protein complexes that modify chromosomal components and reversibly stabilize or destabilize chromatin. Ligand-dependent recruitment of transcriptional coactivators destabilizes chromatin by mechanisms including histone acetylation and contacts with the basal transcriptional machinery. In contrast, the recruitment of corepressors in the absence of ligand or in the presence of hormone antagonists serves to stabilize chromatin by the targeting of histone deacetylases. Both activation and repression require the action of other chromatin remodeling engines of the switch 2/sucrose nonfermentable 2 (SWI2/SNF2) class. Here we summarize this information and integrate hormone action into a chromatin context. Journal of Molecular Endocrinology (1999) 23, 255-275 INTRODUCTIONThe nuclear hormone receptors provide transcription research with a clear example of how the reversible modification of chromatin structure can contribute to the control of gene expression. Remarkable progress in the definition of intermediary protein complexes that activate or repress transcription has allowed common themes in transcriptional control by a wide variety of receptors to emerge. The roles of these coactivators and corepressors in mediating the activities of nuclear receptors within chromatin is a key element of contemporary molecular endocrinology. The beststudied receptors in this regard are those for the glucocorticoid and thyroid hormones.The glucocorticoid receptor recognizes response elements within nucleosomes as a first step towards a finely orchestrated rearrangement of histone-DNA contacts concomitant with the assembly of a functional transcription complex. The determinants of chromatin remodeling and the molecular machines that carry it out are now understood in considerable detail. Likewise, the thyroid hormone receptor recognizes nucleosomal DNA and utilizes chromatin to regulate transcription. However, in this case the receptor exerts a dual function. In the absence of ligand, the thyroid hormone receptor recruits a corepressor complex that stabilizes chromatin structure. Upon addition of hormone the receptor releases this repressive complex, and recruits coactivators that destabilize chromatin and promote transcription.This review illustrates the role of chromatin, coactivators and corepressors in gene control as orchestrated by the glucocorticoid and thyroid hormone receptors. COACTIVATORS AND COREPRESSORS CoactivatorsThe interplay of distinct nuclear receptor responsive transcription pathways has been recognized for 255

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Nucleosomes inhibit both transcriptional initiation and elongation by RNA polymerase III in vitro.

Cited by 106 publications

References 44 publications

The Position and Length of the Steroid-Dependent Hypersensitive Region in the Mouse Mammary Tumor Virus Long Terminal Repeat Are Invariant despite Multiple Nucleosome B Frames

The Position and Length of the Steroid-Dependent Hypersensitive Region in the Mouse Mammary Tumor Virus Long Terminal Repeat Are Invariant despite Multiple Nucleosome B Frames

Transcription on nucleosomal templates by RNA polymerase II in vitro: inhibition of elongation with enhancement of sequence-specific pausing.

Nuclear receptors: coactivators, corepressors and chromatin remodeling in the control of transcription

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