Nucleosome Positioning Is Independent of Histone H1in Vivo

Karrer, Kathleen M.; VanNuland, Teresa A.

doi:10.1074/jbc.274.46.33020

Cited by 13 publications

(15 citation statements)

References 30 publications

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“…Yeast studies have shown that H1 has no effect on nucleosome positioning on the POT1 and the YIL161W genes (38), which are not affected by H1 removal according to our microarray analysis. Similarly, nucleosome positioning is independent of histone H1 in Tetrahymena (39). We observed decreased expression of EFT1 irrespective of its chromosomal location (Table II).…”

Section: Discussionmentioning

confidence: 60%

Decreased Expression of Specific Genes in Yeast Cells Lacking Histone H1

Hellauer¹,

Sirard²,

Turcotte³

2001

Journal of Biological Chemistry

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Section: Discussionmentioning

confidence: 60%

Decreased Expression of Specific Genes in Yeast Cells Lacking Histone H1

Hellauer¹,

Sirard²,

Turcotte³

2001

Journal of Biological Chemistry

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“…Such a change could affect transcription of certain genes in which control of transcription is very sensitive to positioning of specific nucleosomes. On the other hand, the nucleosome repeat length is unchanged in yeast, and Aspergillus nidulans mutants completely lacking linker histones (36,39,45) and nucleosome positions at specific loci were unchanged in the Tetrahymena mutant (46). Therefore, the mechanisms by which linker histones affect gene transcription in mammalian cells and unicellular eukaryotes may be quite different.…”

Section: Table III Functional Categories Of Genes Whose Expression Lementioning

confidence: 91%

Reductions in Linker Histone Levels Are Tolerated in Developing Spermatocytes but Cause Changes in Specific Gene Expression

Lin

Inselman

Han

et al. 2004

Journal of Biological Chemistry

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H1 linker histones are involved in packaging chromatin into 30-nm fibers and higher order structures. Most eukaryotic cells contain nearly one H1 molecule for each nucleosome core particle. Male germ cells in mammals contain large amounts of a germ cell-specific linker histone, HIST1HT, herein denoted H1t, which is particularly abundant in pachytene spermatocytes. Despite its abundance in male germ cells and significant divergence in primary sequence from other H1 subtypes, inactivation of the H1t gene in mice showed that it is not required for spermatogenesis. Analysis of germ cell chromatin from H1t null mice showed that other H1 subtypes, especially the testis-enriched HIST1H1A, herein denoted as the H1a subtype, were able to compensate for the absence of H1t to maintain a normal total H1 to nucleosome core ratio. To disrupt the compensation, we generated H1t and H1a double null mice by two sequential gene-targeting steps in embryonic stem cells. Elimination of both H1t and H1a led to a 25% decrease in the ratio of H1 to nucleosome cores in double null germ cells. Surprisingly, the reduction in H1 did not perturb spermatogenesis or produce detectable defects in meiotic processes. Microarray analysis of gene expression showed that the reduced linker histone levels did not affect global gene expression, but it did cause changes in expression of specific genes. Our results indicate that a partial reduction in linker histone-nucleosome core particle stoichiometry is tolerated in developing male germ cells.

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“…Macronuclei were isolated essentially as described by Karrer and VanNuland (1999). Briefly, 400 ml of cells grown to a density of 3 ϫ 10 5 cells/ml were pelleted and lysed in 60 ml of TMS (10 mM Tris, pH 7.5, 10 mM MgCl 2 , 3 mM CaCl 2 , 250 mM sucrose, 1 mM dithiothreitol) and 0.16% Igepal CA-630 (NP-40) at 4°C.…”

Section: Isolation and Nuclease Digestion Of Macronucleimentioning

confidence: 99%

Modulation of Telomere Length Dynamics by the Subtelomeric Region ofTetrahymenaTelomeres

Jacob

Stout

Price

2004

MBoC

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Tetrahymena telomeres usually consist of ϳ250 base pairs of T 2 G 4 repeats, but they can grow to reach a new length set point of up to 900 base pairs when kept in log culture at 30°C. We have examined the growth profile of individual macronuclear telomeres and have found that the rate and extent of telomere growth are affected by the subtelomeric region. When the sequence of the rDNA subtelomeric region was altered, we observed a decrease in telomere growth regardless of whether the GC content was increased or decreased. In both cases, the ordered structure of the subtelomeric chromatin was disrupted, but the effect on the telomeric complex was relatively minor. Examination of the telomeres from non-rDNA chromosomes showed that each telomere exhibited a unique and characteristic growth profile. The subtelomeric regions from individual chromosome ends did not share common sequence elements, and they each had a different chromatin structure. Thus, telomere growth is likely to be regulated by the organization of the subtelomeric chromatin rather than by a specific DNA element. Our findings suggest that at each telomere the telomeric complex and subtelomeric chromatin cooperate to form a unique higher order chromatin structure that controls telomere length. INTRODUCTIONTelomeres from most organisms exhibit a characteristic mean length that results from a balance between addition of telomeric DNA by telomerase or recombination and loss of DNA due to incomplete replication or nuclease activity (Greider, 1996;McEachern et al., 2000). If this balance is perturbed, telomeres grow or shrink until a new length set point is reached. Factors that control the balance, and hence regulate telomere length, include telomere and telomerase components, replication and repair proteins, and environmental conditions. In Saccharomyces cerevisiae, more than a dozen different proteins have been shown to affect telomere length (Bourns et al., 1998;Blackburn, 2001), whereas rapid proliferation and increased culture temperature induce telomere growth in Tetrahymena, trypanosomes, and Candida albicans (Bernards et al., 1983;Larson et al., 1987;McEachern and Hicks, 1993).In organisms such as Tetrahymena and S. cerevisiae that have relatively short telomeres (250 -350 nt), the entire telomeric tract can be packaged into a nonnucleosomal complex (Blackburn and Chiou, 1981;Wright et al., 1992;Cohen and Blackburn, 1998), but in organisms with longer telomeres, the telomeric DNA is bound by a combination of nucleosomes and specialized telomere proteins (Tommerup et al., 1994). Both short and long telomeres seem to be subject to a second level of packaging that involves folding or looping of the telomeric tract to form a more compact higher order structure (Grunstein, 1997;Griffith et al., 1999). In S. cerevisiae, this folding is mediated by protein-protein interactions with the telomere protein Rap1 interacting with SIR proteins bound to nucleosomes along the subtelomeric region (Grunstein, 1997). In vertebrate and plant cells, the folding seems ...

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Nucleosome Positioning Is Independent of Histone H1in Vivo

Cited by 13 publications

References 30 publications

Decreased Expression of Specific Genes in Yeast Cells Lacking Histone H1

Decreased Expression of Specific Genes in Yeast Cells Lacking Histone H1

Reductions in Linker Histone Levels Are Tolerated in Developing Spermatocytes but Cause Changes in Specific Gene Expression

Modulation of Telomere Length Dynamics by the Subtelomeric Region ofTetrahymenaTelomeres

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