Removal of histone H1 exposes linker DNA in chromatin to DNAse I

Iovcheva, Christina; Mladenova, I.; Dessev, George

doi:10.1007/bf00775147

Cited by 6 publications

(4 citation statements)

References 16 publications

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“…The internucleosomal linker regions of DNA are located inside the 30-nm fiber of chromatin and are protected by the nucleosomes (43). Therefore, proteolysis of structural proteins such as histone H1 is necessary to render the linker regions accessible for a nucleolytic attack (44). This is illustrated by the fact that pure recombinant human DNASE1 cleaved native chromatin of isolated cell nuclei only randomly and with less efficiency.…”

Section: Discussionmentioning

confidence: 99%

Chromatin breakdown during necrosis by serum Dnase1 and the plasminogen system

Napirei¹,

Wulf²,

Mannherz³

2004

Arthritis & Rheumatism

115

120

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Objective. Dnase1-deficient mice with the 129 ؋ C57BL/6 genetic background develop symptoms of systemic lupus erythematosus, such as high titers of antinuclear autoantibodies directed against nucleosomes. In this study we analyzed a potential molecular pathomechanism leading to this autoimmunity, by exploring the influence of extracellular Dnase1 present in serum on the breakdown of chromatin in necrotic cells in vitro.Methods. Human breast adenocarcinoma cells (MCF-7) and other cell lines were subjected to necrosis induced by hydrogen peroxide, streptolysin O, or freezethawing. Subsequently, the influence of sera from Dnase1-deficient and wild-type mice as well as the influence of purified enzymes present in the culture medium on the process of necrotic chromatin breakdown was investigated.Results. Necrotic chromatin breakdown resembled apoptotic DNA laddering and was catalyzed by serum Dnase1 in conjunction with plasmin. During necrosis, Dnase1 and plasminogen penetrated the cell and accumulated in the cytoplasm and nucleus. Plasminogen bound to the cytoskeleton and nuclear structures, was activated to plasmin by either tissue-type or urokinase-type plasminogen activator, and degraded histone H1, thereby facilitating internucleosomal DNA cleavage by Dnase1.Conclusion. Our results suggest that serum Dnase1 in cooperation with the plasminogen system guarantees a fast and effective breakdown of chromatin during necrosis by the combined cleavage of DNA as well as of DNA binding proteins. The failure of such a clearance mechanism might lead to antinuclear autoimmunity similar to that observed in the Dnase1-deficient mouse.

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Section: Discussionmentioning

confidence: 99%

Chromatin breakdown during necrosis by serum Dnase1 and the plasminogen system

Napirei¹,

Wulf²,

Mannherz³

2004

Arthritis & Rheumatism

115

120

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“…Such factors might, nonetheless, stimulate Alu transcription by altering chromatin. As one possibility, histone H1 influences the length of linker DNA between nuclesomes, depleting H1 opens chromatin to nuclease digestion and H1 represses Pol III transcription of xenopus oocyte 5S genes and mouse B2 repeats (12,(56)(57)(58)(59). However, despite these attractive connections, depleting H1 from HeLa chromatin has little effect upon Alu promoter activity in vitro (37,38).…”

Section: Discussionmentioning

confidence: 99%

K562 cells implicate increased chromatin accessibility in Alu transcriptional activation

Kim²,

Rubin³

et al. 2000

Nucleic Acids Research

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Alu repeats in K562 cells are unusually hypomethylated and far more actively transcribed than those in other human cell lines and somatic tissues. Also, the level of Alu RNA in K562 cells is relatively insensitive to cell stresses, namely heat shock, adenovirus infection and treatment with cycloheximide, which increase the abundance of Alu RNA in HeLa and 293 cells. Recent advances in understanding the interactions between DNA methylation, transcriptional activation and chromatin conformation reveal reasons for the constitutively high level of Alu expression in K562 cells. Methylation represses transcription of transiently transfected Alu templates in all cell lines tested but cell stresses do not relieve this repression suggesting that they activate Alu transcription through another pathway. A relatively large fraction of the Alus within K562 chromatin is accessible to restriction enzyme cleavage and cell stresses increase the chromatin accessibility of Alus in HeLa and 293 cells. Cell stress evidently activates Alu transcription by rapidly remodeling chromatin to recruit additional templates.

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“…Chicken histone octamers were isolated from salt-stripped chicken erythrocyte chromatin (26) by the method of Simon and Felsenfeld (27) and stored at Ϫ20°C in 2 M NaCl and 50% glycerol. Trypsin-treated chicken histone octamers were prepared by trypsin digestion of salt-stripped chromatin in 25 mM NaCl, 10 mM Tris, pH 7.5, at a mass ratio of 1,000:1 for 5 min at 37°C followed by the addition of a 100-fold excess of soybean trypsin inhibitor and hydroxyapatite chromatography (27).…”

Section: Methodsmentioning

confidence: 99%

Assembly, Remodeling, and Histone Binding Capabilities of Yeast Nucleosome Assembly Protein 1

McQuibban

Commisso-Cappelli

Lewis

1998

Journal of Biological Chemistry

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Recombinant yeast nucleosome assembly protein (yNAP-1) facilitates the formation of uniformly spaced nucleosomes from high molecular weight DNA and core histone octamers. No additional factors or metabolites are required. The repeat length of the chromatin produced is about 146 base pairs. To obtain the most distinct nucleosomal ladders, the core histones must preexist as an octamer complex. yNAP-1 forms complexes with core histones as judged by native gel electrophoresis, chemical cross-linking, limited histone proteolysis, and affinity blotting. A discrete complex was observed with a probable ratio of yNAP-1 to histone octamer of 4:1. Chromatin produced by salt dialysis does not contain uniformly spaced nucleosomes, but subsequent incubation with yNAP-1 creates uniform spacing. Trypsintreated core octamers that lack amino termini, although capable of forming core particles with core-length DNA by salt dialysis, are not assembled by yNAP-1 into uniformly spaced nucleosomes on high molecular weight DNA. Proteolytic removal of the amino termini of the core histones precludes complex formation between a histone octamer and yNAP-1. Affinity blotting also demonstrates that yNAP-1 binds linker histones and high mobility group (HMG)-1/HMG-2 but not HMG-14. Competition experiments with poly-L-arginine, poly-L-lysine, and protamine reveal that yNAP-1 binds to core and linker histones more tightly despite the much higher positive charge densities of the former molecules. Naturally occurring acetylated histone H4 species show no evidence for differential yNAP-1 binding. yNAP-1 is not bound tightly to the resulting chromatin after deposition and thus could act catalytically.In eukaryotes, chromosomal DNA encircles octamers of core histones resulting in arrays of nucleosomes which represent the first level of chromatin organization. To a first approximation, these nucleosomal arrays are spaced uniformly with characteristic repeat lengths that can vary from species to species, from tissue to tissue, and even with the transcriptional state of the chromatin under consideration (1). Although the primary organization of nucleosomes along the chromatin fiber appears uniform, many studies have shown convincingly that chromatin can exist in a variety of states characterized by the sensitivity of the DNA to cleavage by chemical agents and nucleases (2). These states can change markedly with gene expression and are thought to be associated with nucleosome loss, disruption, or remodeling (3, 4).Core nucleosomes and chromatin can be reconstituted readily in vitro from their constituents by methods such as dialysis from high ionic strength solutions (2) or by the addition of negatively charged macromolecules such as nucleoplasmin, polyglutamic acid, pectin, and RNA (5-9). These protocols result in the non-uniform placement of nucleosomes along the chromatin fiber which, when digested with micrococcal nuclease, results mainly in mononucleosomes and spacerless dinucleosomes (10). Adding DNA to preparations of whole, unfractionated cellula...

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Removal of histone H1 exposes linker DNA in chromatin to DNAse I

Cited by 6 publications

References 16 publications

Chromatin breakdown during necrosis by serum Dnase1 and the plasminogen system

Chromatin breakdown during necrosis by serum Dnase1 and the plasminogen system

K562 cells implicate increased chromatin accessibility in Alu transcriptional activation

Assembly, Remodeling, and Histone Binding Capabilities of Yeast Nucleosome Assembly Protein 1

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