Incorporation of exogenous pyrene-labeled histone into Physarum chromatin: a system for studying changes in nucleosomes assembled in vivo

Prior, Christopher P.; Cantor, Charles R.; Johnson, Edward M.; Allfrey, Vincent G.

doi:10.1016/0092-8674(80)90306-2

Cited by 111 publications

(70 citation statements)

References 21 publications

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“…Based on a variety of experiments involving bulk chromatin, it has been long believed that in S phase, nucleosomes deposited on newly synthesized DNA are generated from newly synthesized histones and do not involve histone subunits from preexisting nucleosomes (2,(4)(5)(6)(7)(8). A recent paper focusing on the histone variant H3.1, which is deposited specifically during DNA replication, revealed that newly synthesized H3.1 did not form mixed tetramers with preexisting H3 molecules, confirming that nucleosomes are conservatively inherited during DNA replication (13).…”

Section: Discussionmentioning

confidence: 99%

“…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 received little support from a variety of studies, which failed to detect old and new H3-H4 dimers within the same nucleosome (2,(4)(5)(6)(7)(8). A notable exception was an analysis of active chromatin from chicken cells suggesting substantial levels of mixed tetramers (9).…”

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confidence: 99%

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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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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

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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“…npg cleosomes, which carry the modifications most likely to be involved in epigenetic phenomena, do not dissociate during replication-dependent nucleosome assembly [24][25][26][27]. However, expectations for the H3-H4 tetramer split model revived in the past few years, after the discoveries that H3-H4 histones deposit onto chromatin as dimers rather than tetramers [28][29][30], and that the histone chaperone Asf1 blocks H3-H4 tetramer formation [31,32] and even disrupts pre-assembled H3-H4 tetramers to form H3-H4/Asf1 heterotrimers [32].…”

Section: Bing Zhu and Danny Reinberg 437mentioning

confidence: 99%

Epigenetic inheritance: Uncontested?

Reinberg

2011

Cell Res

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"Epigenetics" is currently defined as "the inheritance of variation (-genetics) above and beyond (epi-) changes in the DNA sequence". Despite the fact that histones are believed to carry important epigenetic information, little is known about the molecular mechanisms of the inheritance of histone-based epigenetic information, including histone modifications and histone variants. Here we review recent progress and discuss potential models for the mitotic inheritance of histone modifications-based epigenetic information.

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“…Historically, there are good evidences for the H3/H4 tetramer non-split model. In 1980, using the slime mold Physarum as a model, Prior et al (1980) examined the long term stability of H3-H3 interactions. Data showed that, even after five rounds of DNA replication, the original H3-H3 interaction can still be detected, indicating that (H3/H4) 2 tetramers are stable during multiple cell generations in vivo (Prior et al, 1980).…”

Section: H3/h4 Segregated To Daughter Strands As Tetramersmentioning

confidence: 99%

“…In 1980, using the slime mold Physarum as a model, Prior et al (1980) examined the long term stability of H3-H3 interactions. Data showed that, even after five rounds of DNA replication, the original H3-H3 interaction can still be detected, indicating that (H3/H4) 2 tetramers are stable during multiple cell generations in vivo (Prior et al, 1980). Ten years after this discovery, Jackson studied the fate of (H3/H4) 2 tetramers in proliferating mammalian cultured cell via density labeling and sedimentation approach (Jackson, 1990).…”

Section: H3/h4 Segregated To Daughter Strands As Tetramersmentioning

confidence: 99%

Nucleosome assembly and epigenetic inheritance

2010

Protein Cell

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In eukaryotic cells, histones are packaged into octameric core particles with DNA wrapping around to form nucleosomes, which are the basic units of chromatin (Kornberg and Thomas, 1974). Multicellular organisms utilise chromatin marks to translate one single genome into hundreds of epigenomes for their corresponding cell types. Inheritance of epigenetic status is critical for the maintenance of gene expression profile during mitotic cell divisions . During S phase, canonical histones are deposited onto DNA in a replication-coupled manner . To understand how dividing cells overcome the dilution of epigenetic marks after chromatin duplication, DNA replication coupled (RC) nucleosome assembly has been of great interest. In this review, we focus on the potential influence of RC nucleosome assembly processes on the maintenance of epigenetic status.

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Incorporation of exogenous pyrene-labeled histone into Physarum chromatin: a system for studying changes in nucleosomes assembled in vivo

Cited by 111 publications

References 21 publications

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

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

Epigenetic inheritance: Uncontested?

Nucleosome assembly and epigenetic inheritance

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