NoRC--a novel member of mammalian ISWI-containing chromatin remodeling machines

Strohner, Ralf; Németh, Attila; Jansa, P; Hofmann-Rohrer, Urs; Santoro, Raffaella; Längst, Gernot; Grummt, Ingrid

doi:10.1093/emboj/20.17.4892

Cited by 283 publications

(280 citation statements)

References 43 publications

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“…Later multiple additional remodelers belonging to this group were identified in yeast [75], humans [76,77], mouse [78], and Xenopus [79] (Figure 2). The ATPase subunit of this group of chromatin remodeling enzymes has been named Imitation SWItch (ISWI) because of its similarity to the SWI2 ATPase in the SNF2 subfamily.…”

Section: Iswi Familymentioning

confidence: 99%

Mechanisms of ATP dependent chromatin remodeling

Gangaraju

Bartholomew

2007

Mutation Research/Fundamental and Molecular Mechanisms of Mutag

128

159

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The inter-relationship between DNA repair and ATP dependent chromatin remodeling has begun to become very apparent with recent discoveries. ATP dependent remodeling complexes mobilize nucleosomes along DNA, promote the exchange of histones, or completely displace nucleosomes from DNA. These remodeling complexes are often categorized based on the domain organization of their catalytic subunit. The biochemical properties and structural information of several of these remodeling complexes are reviewed. The different models for how these complexes are able to mobilize nucleosomes and alter nucleosome structure are presented incorporating several recent findings. Finally the role of histone tails and their respective modifications in ATP-dependent remodeling are discussed.

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Section: Iswi Familymentioning

confidence: 99%

Mechanisms of ATP dependent chromatin remodeling

Gangaraju

Bartholomew

2007

Mutation Research/Fundamental and Molecular Mechanisms of Mutag

128

159

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“…A key component of the rRNA gene on/off switch in mammals is a specialized chromatin remodelling activity known as NoRC (Nucleolar Remodelling Complex; see Figure 4) [63]. The discovery of NoRC in the Grummt lab came about in an interesting way.…”

Section: Rrna Gene Dosage Control Mechanisms and The Mammalian Norc Cmentioning

confidence: 99%

“…A yeast two hybrid screen for TTF-I-interacting partners identified TIP5 (TTF-I-interaction protein #5), which, in turn interacts with SNF2h, an ATP-dependent chromatin remodeling protein. Collectively, TIP5 and SNF2h comprise NoRC [63].…”

Section: Rrna Gene Dosage Control Mechanisms and The Mammalian Norc Cmentioning

confidence: 99%

“…Once the on/off decision has been made, eukaryotic cells then appear to regulate the frequency at which RNA polymerase I initiates on each active gene in order to fine-tune the amount of rRNA produced. Studies in yeast and mammals indicate that fine-tuning is accomplished primarily through signal transduction mechanisms that lead to the post-translational modification of essential RNA polymerase I transcription factors [57][58][59][60][61][62].A key component of the rRNA gene on/off switch in mammals is a specialized chromatin remodelling activity known as NoRC (Nucleolar Remodelling Complex; see Figure 4) [63]. The discovery of NoRC in the Grummt lab came about in an interesting way.…”

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confidence: 99%

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rRNA gene silencing and nucleolar dominance: Insights into a chromosome-scale epigenetic on/off switch

Preuss

Pikaard

2007

Biochimica et Biophysica Acta (BBA) - Gene Structure and Expres

135

105

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Ribosomal RNA (rRNA) gene transcription accounts for most of the RNA in prokaryotic and eukaryotic cells. In eukaryotes, there are hundreds (to thousands) of rRNA genes tandemly repeated head-to-tail within nucleolus organizer regions (NORs) that span millions of basepairs. These nucleolar rRNA genes are transcribed by RNA Polymerase I (Pol I) and their expression is regulated according to the physiological need for ribosomes. Regulation occurs at several levels, one of which is an epigenetic on/off switch that controls the number of active rRNA genes. Additional mechanisms then fine-tune transcription initiation and elongation rates to dictate the total amount of rRNA produced per gene. In this review, we focus on the DNA and histone modifications that comprise the epigenetic on/off switch. In both plants and animals, this system is important for controlling the dosage of active rRNA genes. The dosage control system is also responsible for the chromatinmediated silencing of one parental set of rRNA genes in genetic hybrids, a large-scale epigenetic phenomenon known as nucleolar dominance.Keywords epigenetic phenomena; RNA polymerase I; DNA methylation; cytosine methylation; histone methylation; histone deacetylation; histone deacetylase; transcription; ribosomal RNA; nucleolus; nucleolus organizer region Large scale cytological effects of rRNA gene regulation: nucleolus and secondary constriction formationThe most prominent feature of a eukaryotic nucleus during interphase is the nucleolus (Figure 1), a region that contains relatively little chromosomal DNA but is rich in RNAs, proteins and ribonucleoprotein particles, including the large and small ribosome subunits as they undergo assembly [1][2][3]. The location of a nucleolus is not determined randomly; instead its formation is determined by the position of a discrete chromosomal locus known as a nucleolus organizer region, or NOR [4]. This fact was discovered based on an intriguing property: upon condensation of chromosomes at metaphase, NORs fail to condense to the same extent as surrounding chromosomal sequences and thus give rise to "secondary constrictions", with "primary constrictions" being defined as the centromeres (see Figure 1). Heitz initially noted that nucleoli form at, or very near, the sites of secondary constrictions [5] and McClintock soon thereafter obtained direct evidence [6]. She identified a maize line in which a chromosome break at or near the secondary constriction on chromosome 9, followed by translocation of one *Author to whom correspondence should be addressed: pikaard@biology2.wustl.edu, phone: Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the conte...

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“…In vertebrates, members of the ISWI subfamily are the ATPase subunits of the RSF complex, (23) hACF/WCRF complex, (29,45) xACF, (46) WICH complex, (47) hCHRAC (48) and NoRC. (49) In addition, ISW1 and ISW2 are the catalytic subunits of chromatin-remodeling complexes in yeast. (50)(51)(52) ISWI has also been observed to copurify with a Drosophila TRF2 complex.…”

Section: Activities Of Chromatin-remodeling Factorsmentioning

confidence: 99%

Chromatin remodeling by ATP‐dependent molecular machines

2003

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SummaryThe eukaryotic genome is packaged into a periodic nucleoprotein structure termed chromatin. The repeating unit of chromatin, the nucleosome, consists of DNA that is wound nearly two times around an octamer of histone proteins. To facilitate DNA-directed processes in chromatin, it is often necessary to rearrange or to mobilize the nucleosomes. This remodeling of the nucleosomes is achieved by the action of chromatin-remodeling complexes, which are a family of ATP-dependent molecular machines. Chromatin-remodeling factors share a related ATPase subunit and participate in transcriptional regulation, DNA repair, homologous recombination and chromatin assembly. In this review, we provide an overview of chromatin-remodeling enzymes and discuss two possible mechanisms by which these factors might act to reorganize nucleosome structure.

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NoRC--a novel member of mammalian ISWI-containing chromatin remodeling machines

Cited by 283 publications

References 43 publications

Mechanisms of ATP dependent chromatin remodeling

Mechanisms of ATP dependent chromatin remodeling

rRNA gene silencing and nucleolar dominance: Insights into a chromosome-scale epigenetic on/off switch

Chromatin remodeling by ATP‐dependent molecular machines

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