Histone chaperones regulate histone exchange during transcription

Kim, Hye-Jin; Seol, Ja-Hwan; Han, Jeung‐Whan; Youn, Hwa Young; Cho, Eun Jung

doi:10.1038/sj.emboj.7601870

Cited by 50 publications

(56 citation statements)

References 46 publications

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“…4E). Asf1a was additionally detected in the coding region consistent with its role in transcriptional elongation (31,32). However, unexpectedly, their occupancy was either not changed or marginally decreased, depending on the loci, as myoblasts differentiated into myotubes.…”

Section: Myotube-specific and Differentiation-associated H33 Depositmentioning

confidence: 75%

Myogenic transcriptional activation of MyoD mediated by replication-independent histone deposition

Yang

Song

Seol

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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In mammals, the canonical histone H3 and the variant H3.3 are assembled into chromatin through replication-coupled and replication-independent (RI) histone deposition pathways, respectively, to play distinct roles in chromatin function. H3.3 is largely associated with transcriptionally active regions via the activity of RI histone chaperone, HIRA. However, the precise role of the RI pathway and HIRA in active transcription and the mechanisms by which H3.3 affects gene activity are not known. In this study, we show that HIRA is an essential factor for muscle development by establishing MyoD activation in myotubes. HIRA and Asf1a, but not CHD1 or Asf1b, mediate H3.3 incorporation in the promoter and the critical upstream regulatory regions of the MyoD gene. HIRA and H3.3 are required for epigenetic transition into the more permissive chromatin structure for polymerase II recruitment to the promoter, regardless of transcription-associated covalent modification of histones. Our results suggest distinct epigenetic management of the master regulator with RI pathway components for cellular differentiation.

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Section: Myotube-specific and Differentiation-associated H33 Depositmentioning

confidence: 75%

Myogenic transcriptional activation of MyoD mediated by replication-independent histone deposition

Yang

Song

Seol

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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“…The restriction of tetramer splitting to regions of high nucleosome exchange may be explained by differences in the biochemical properties of these factors or by other differences between DNA replication and transcription. The histone chaperones Asf1, HIR, FACT, and Spt6 are important for transcription-coupled exchange of histones H3 and H4 (16,(26)(27)(28)(29). The crystal structure of Asf1 bound to an H3-H4 dimer prompted a "strand capture" model, in which Asf1 splits H3-H4 tetramers into dimers during nucleosome disassembly by interacting with the H4 tail (30), and this mechanism is supported by biochemical analyses (3,31).…”

Section: Relative Ip Efficiencymentioning

confidence: 83%

Splitting of H3–H4 tetramers at transcriptionally active genes undergoing dynamic histone exchange

Katan-Khaykovich

Struhl

2011

Proc. Natl. Acad. Sci. U.S.A.

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Nucleosome deposition occurs on newly synthesized DNA during DNA replication and on transcriptionally active genes via nucleosome-remodeling complexes recruited by activator proteins and elongating RNA polymerase II. It has been long believed that histone deposition involves stable H3-H4 tetramers, such that newly deposited nucleosomes do not contain H3 and H4 molecules with their associated histone modifications from preexisting nucleosomes. However, biochemical analyses and recent experiments in mammalian cells have raised the idea that preexisting H3-H4 tetramers might split into dimers, resulting in mixed nucleosomes composed of "old" and "new" histones. It is unknown to what extent different genomic loci might utilize such a mechanism and under which circumstances. Here, we address whether tetramer splitting occurs in a locus-specific manner by using sequential chromatin immunoprecipitation of mononucleosomes from yeast cells containing two differentially tagged versions of H3 that are expressed "old" and "new" histones. At many genomic loci, we observe little or no nucleosomal cooccupancy of old and new H3, indicating that tetramer splitting is generally infrequent. However, cooccupancy is detected at highly active genes, which have a high rate of histone exchange. Thus, DNA replication largely results in nucleosomes bearing exclusively old or new H3-H4, thereby precluding the acquisition of new histone modifications based on preexisting modifications within the same nucleosome. In contrast, tetramer splitting, dimer exchange, and nucleosomes with mixed H3-H4 tetramers occur at highly active genes, presumably linked to rapid histone exchange associated with robust transcription.T he packaging of eukaryotic DNA into chromatin influences many DNA-associated processes, including transcriptional regulation. Within the chromatin fiber, each basic nucleosome unit bears important chemical and structural information. The mechanisms by which nucleosomes are assembled on DNA during replication, transcription, DNA repair, etc., can thus impact not only the integrity of chromatin structure but also patterns of gene expression and epigenetic inheritance. The H3-H4 tetramer core of each nucleosome is the more stable component and contains most of the relatively persistent and functionally important histone methylation marks. Much attention has therefore been given to the questions of how the H3-H4 tetramers are formed and maintained on chromatin.Early studies attempted to distinguish between a conservative assembly model, by which old and new histones form separate tetramers on replicating DNA, and a semiconservative assembly mechanism, by which existing tetramers are split into H3-H4 dimers, followed by association of new H3-H4 dimers to complete each nucleosome core (1-3). In the semiconservative model, the resulting tetramers would bear a mixture of old and new histones, allowing transmission of epigenetic information within the basic nucleosome unit. Though mechanistically attractive, the mixed tetramer model receiv...

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“…This intriguing mechanism needs to be tested in vitro. Despite the well-documented role of Asf1 in nucleosome eviction in vivo [35]; [54] and references therein), there is no in vitro evidence that Asf1 can directly mediate nucleosome disassembly, either alone or together with ATP-dependent remodelers or H2A/H2B chaperones. It should be pointed out that the concept of the H3/H4 dimer as the intermediate for nucleosome assembly has been proposed previously [55].…”

Section: Chaperone -Histone Interactions and Implications For Nucleosmentioning

confidence: 99%

Histone chaperones in nucleosome eviction and histone exchange

Park

Luger

2008

Current Opinion in Structural Biology

172

143

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Histone chaperones regulate histone exchange during transcription

Cited by 50 publications

References 46 publications

Myogenic transcriptional activation of MyoD mediated by replication-independent histone deposition

Myogenic transcriptional activation of MyoD mediated by replication-independent histone deposition

Splitting of H3–H4 tetramers at transcriptionally active genes undergoing dynamic histone exchange

Histone chaperones in nucleosome eviction and histone exchange

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