scholarly journals Site-specific phosphorylation of histone H1.4 is associated with transcription activation

2019 ◽  
Author(s):  
Ankita Saha ◽  
Christopher Seward ◽  
Lisa Stubbs ◽  
Craig Andrew Mizzen
Keyword(s):  
Posttranslational Modifications ◽  
Distribution Patterns ◽  
Histone Variants ◽  
Linker Histone ◽  
Sequence Variant ◽  
Mcf7 Cells ◽  
Linker Histones ◽  
Direct Contrast ◽  
Active Transcription ◽  
Modified Forms

ABSTRACTCore histone variants like H2A.X and H3.3 and their modified forms serve specialized roles in chromatin processes that depend on their genomic distributions and their interaction with chromatin components. Similarly, previous evidence from our lab and others suggest that amino acid sequence variant forms of the linker histone family and specific posttranslational modifications on these variants also result in distinct functions. These inferences are contrary to the notion that the H1 family function as redundant repressors. Here, we provide the first genome-wide evidence that when phosphorylated at a specific C-terminal domain site i.e serine 187, the linker histone H1.4 is enriched at active promoters. This is in direct contrast to previous reports that suggest that phosphorylation of H1 leads to their dissociation from chromatin. Using a highly specific pS187H1.4 antibody earlier developed in the lab, we studied the distribution patterns of pS187H1.4 in estradiol-responsive MCF7 cells where we demonstrated the inducible nature of this modification. We also used public MCF7 data to confirm the association of pS187H1.4 with well-known active transcription marks. These data suggest that linker histones and their modified forms have a more nuanced role than previously understood and may even play a role in transcription regulation.

scholarly journals Phosphorylation of linker histone is associated with transcriptional activation in a normally silent nucleus.

1996 ◽  
Vol 135 (5) ◽  
pp. 1219-1228 ◽  
Author(s):  
M T Sweet ◽  
K Jones ◽  
C D Allis
Keyword(s):  
Transcriptional Activation ◽  
Signal Transduction Pathway ◽  
Linker Histone ◽  
Transduction Pathway ◽  
Dependent Protein Kinase ◽  
Linker Histones ◽  
Blocking Pair ◽  
Dependent Protein ◽  
Active Transcription

Previous studies have suggested that micronuclear linker histones are phosphorylated by cAMP-dependent protein kinase (PKA) in Tetrahymena (Sweet, M.T., and C.D. Allis. 1993. Chromosoma. 102: 637-647). In this study, we report that a rapid and dramatic phosphorylation of the micronuclear linker histone, delta, occurs early in the sexual pathway, conjugation. Phosphorylated isoforms of delta are detected as early as 30 min after mixing cells of different mating types; blocking pair formation abolishes this induction completely. Phosphorylation of delta is stimulated by the addition of N6-benzoyladenosine 3':5' cyclic monophosphate to starved (nonmating) cells, suggesting that a PKA/cAMP signal transduction pathway is involved. Maximal phosphorylation of delta is observed during meiotic prophase, a period when micronuclei become transcriptionally active. In situ staining, using phospho-delta-specific antibodies combined with [3H]uridine autoradiography, shows that decondensed micronuclear chromatin undergoing active transcription is enriched in phosphorylated delta isoforms. In contrast, condensed inactive micronuclear chromatin is enriched in dephosphorylated delta. These results strongly suggest that phosphorylation of linker histone plays an important and previously unsuspected role in establishing transcriptional competence in micronuclei.

scholarly journals Elucidating the influence of linker histone variants on chromatosome dynamics and energetics

2020 ◽  
Vol 48 (7) ◽  
pp. 3591-3604 ◽  
Author(s):  
Dustin C Woods ◽  
Jeff Wereszczynski
Keyword(s):  
Histone Variants ◽  
Linker Histone ◽  
Globular Domain ◽  
Binding Modes ◽  
Binding Motifs ◽  
Linker Histones ◽  
Biophysical Studies ◽  
Dynamics Simulations ◽  
Physical And Chemical ◽  
Linker Histone Variants

Abstract Linker histones are epigenetic regulators that bind to nucleosomes and alter chromatin structures and dynamics. Biophysical studies have revealed two binding modes in the linker histone/nucleosome complex, the chromatosome, where the linker histone is either centered on or askew from the dyad axis. Each has been posited to have distinct effects on chromatin, however the molecular and thermodynamic mechanisms that drive them and their dependence on linker histone compositions remain poorly understood. We present molecular dynamics simulations of chromatosomes with the globular domain of two linker histone variants, generic H1 (genGH1) and H1.0 (GH1.0), to determine how their differences influence chromatosome structures, energetics and dynamics. Results show that both unbound linker histones adopt a single compact conformation. Upon binding, DNA flexibility is reduced, resulting in increased chromatosome compaction. While both variants enthalpically favor on-dyad binding, energetic benefits are significantly higher for GH1.0, suggesting that GH1.0 is more capable than genGH1 of overcoming the large entropic reduction required for on-dyad binding which helps rationalize experiments that have consistently demonstrated GH1.0 in on-dyad states but that show genGH1 in both locations. These simulations highlight the thermodynamic basis for different linker histone binding motifs, and details their physical and chemical effects on chromatosomes.

scholarly journals Regulation of Cellular Dynamics and Chromosomal Binding Site Preference of Linker Histones H1.0 and H1.X

2016 ◽  
Vol 36 (21) ◽  
pp. 2681-2696 ◽  
Author(s):  
Mitsuru Okuwaki ◽  
Mayumi Abe ◽  
Miharu Hisaoka ◽  
Kyosuke Nagata
Keyword(s):  
Binding Site ◽  
Dynamic Behavior ◽  
Histone Variants ◽  
Linker Histone ◽  
Site Preference ◽  
Globular Domain ◽  
Linker Histones ◽  
Terminal Domain ◽  
Site Preferences ◽  
Linker Histone Variants

Linker histones play important roles in the genomic organization of mammalian cells. Of the linker histone variants, H1.X shows the most dynamic behavior in the nucleus. Recent research has suggested that the linker histone variants H1.X and H1.0 have different chromosomal binding site preferences. However, it remains unclear how the dynamics and binding site preferences of linker histones are determined. Here, we biochemically demonstrated that the DNA/nucleosome and histone chaperone binding activities of H1.X are significantly lower than those of other linker histones. This explains why H1.X moves more rapidly than other linker histonesin vivo. Domain swapping between H1.0 and H1.X suggests that the globular domain (GD) and C-terminal domain (CTD) of H1.X independently contribute to the dynamic behavior of H1.X. Our results also suggest that the N-terminal domain (NTD), GD, and CTD cooperatively determine the preferential binding sites, and the contribution of each domain for this determination is different depending on the target genes. We also found that linker histones accumulate in the nucleoli when the nucleosome binding activities of the GDs are weak. Our results contribute to understanding the molecular mechanisms of dynamic behaviors, binding site selection, and localization of linker histones.

scholarly journals Elucidating the Influence of Linker Histone Variants on Chromatosome Dynamics and Energetics

2019 ◽  
Author(s):  
Dustin C. Woods ◽  
Jeff Wereszczynski
Keyword(s):  
Histone Variants ◽  
Linker Histone ◽  
Globular Domain ◽  
Binding Modes ◽  
Binding Motifs ◽  
Linker Histones ◽  
Biophysical Studies ◽  
Dynamics Simulations ◽  
Physical And Chemical ◽  
Linker Histone Variants

AbstractLinker histones are epigenetic regulators that bind to nucleosomes and alter chromatin structures and dynamics. Biophysical studies have revealed two binding modes in the linker histone/nucleosome complex, the chromatosome, where the linker histone is either centered on or askew from the dyad axis. Each has been posited to have distinct effects on chromatin, however the molecular and thermodynamic mechanisms that drive them and their dependence on linker histone compositions remain poorly understood. We present molecular dynamics simulations of chromatosomes with the globular domain of two linker histone variants, generic H1 (genGH1) and H1.0 (GH1.0), to determine how their differences influence chromatosome structures, energetics, and dynamics. Results show that both unbound linker histones adopt a single compact conformation. Upon binding, DNA flexibility is reduced, resulting in increased chromatosome compaction. While both variants enthalpically favor on-dyad binding, energetic benefits are significantly higher for GH1.0, suggesting that GH1.0 is more capable than genGH1 of overcoming the large entropic reduction required for on-dyad binding which helps rationalize experiments that have consistently demonstrated GH1.0 in on-dyad states but that show genGH1 in both locations. These simulations highlight the thermodynamic basis for different linker histone binding motifs, and details their physical and chemical effects on chromatosomes.

scholarly journals Site-specific ubiquitylation acts as a regulator of linker histone H1

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Eva Höllmüller ◽  
Simon Geigges ◽  
Marie L. Niedermeier ◽  
Kai-Michael Kammer ◽  
Simon M. Kienle ◽  
...  
Keyword(s):  
Posttranslational Modifications ◽  
Histone H1 ◽  
Linker Histone ◽  
Active Chromatin ◽  
Site Specific ◽  
Linker Histone H1 ◽  
Fundamental Process ◽  
Core Histones ◽  
Wide Scale

AbstractDecoding the role of histone posttranslational modifications (PTMs) is key to understand the fundamental process of epigenetic regulation. This is well studied for PTMs of core histones but not for linker histone H1 in general and its ubiquitylation in particular due to a lack of proper tools. Here, we report on the chemical synthesis of site-specifically mono-ubiquitylated H1.2 and identify its ubiquitin-dependent interactome on a proteome-wide scale. We show that site-specific ubiquitylation of H1 at position K64 modulates interactions with deubiquitylating enzymes and the deacetylase SIRT1. Moreover, it affects H1-dependent chromatosome assembly and phase separation resulting in a more open chromatosome conformation generally associated with a transcriptionally active chromatin state. In summary, we propose that site-specific ubiquitylation plays a general regulatory role for linker histone H1.

scholarly journals Label-Free Mass Spectrometry-Based Quantification of Linker Histone H1 Variants in Clinical Samples

2020 ◽  
Vol 21 (19) ◽  
pp. 7330
Author(s):  
Roberta Noberini ◽  
Cristina Morales Torres ◽  
Evelyn Oliva Savoia ◽  
Stefania Brandini ◽  
Maria Giovanna Jodice ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Histone H1 ◽  
Histone Variants ◽  
Linker Histone ◽  
Clinical Samples ◽  
Label Free ◽  
Complex Samples ◽  
Linker Histone H1 ◽  
Ideal Tool ◽  
Free Quantification

Epigenetic aberrations have been recognized as important contributors to cancer onset and development, and increasing evidence suggests that linker histone H1 variants may serve as biomarkers useful for patient stratification, as well as play an important role as drivers in cancer. Although traditionally histone H1 levels have been studied using antibody-based methods and RNA expression, these approaches suffer from limitations. Mass spectrometry (MS)-based proteomics represents the ideal tool to accurately quantify relative changes in protein abundance within complex samples. In this study, we used a label-free quantification approach to simultaneously analyze all somatic histone H1 variants in clinical samples and verified its applicability to laser micro-dissected tissue areas containing as low as 1000 cells. We then applied it to breast cancer patient samples, identifying differences in linker histone variants patters in primary triple-negative breast tumors with and without relapse after chemotherapy. This study highlights how label-free quantitation by MS is a valuable option to accurately quantitate histone H1 levels in different types of clinical samples, including very low-abundance patient tissues.

scholarly journals Rapid replacement of somatic linker histones with the oocyte-specific linker histone H1foo in nuclear transfer

2004 ◽  
Vol 266 (1) ◽  
pp. 76-86 ◽  
Author(s):  
Takahide Teranishi ◽  
Mamoru Tanaka ◽  
Shingo Kimoto ◽  
Yukiko Ono ◽  
Kei Miyakoshi ◽  
...  
Keyword(s):  
Nuclear Transfer ◽  
Linker Histone ◽  
Linker Histones ◽  
Rapid Replacement

scholarly journals macroH2A1 Histone Variants Are Depleted on Active Genes but Concentrated on the Inactive X Chromosome

2006 ◽  
Vol 26 (12) ◽  
pp. 4410-4420 ◽  
Author(s):  
Lakshmi N. Changolkar ◽  
John R. Pehrson
Keyword(s):  
X Chromosome ◽  
Distribution Patterns ◽  
Detailed Examination ◽  
Histone Variants ◽  
Heterochromatin Protein ◽  
Inactive X Chromosome ◽  
Preferential Localization ◽  
Intergenic Regions ◽  
Liver Chromatin ◽  
Active Genes

ABSTRACT Using a novel thiol affinity chromatography approach to purify macroH2A1-containing chromatin fragments, we examined the distribution of macroH2A1 histone variants in mouse liver chromatin. We found that macroH2A1 was depleted on the transcribed regions of active genes. This depletion was observed on all of the 20 active genes that we probed, with only one site showing a small amount of enrichment. In contrast, macroH2A1 was concentrated on the inactive X chromosome, consistent with our previous immunofluorescence studies. This preferential localization was seen on genes that are active in liver, genes that are inactive in liver, and intergenic regions but was absent from four regions that escape X inactivation. These results support the hypothesis that macroH2As function as transcriptional repressors. Also consistent with this hypothesis is our finding that the heterochromatin protein HP1β copurifies with the macroH2A1-containing chromatin fragments. This study presents the first detailed examination of the distribution of macroH2A1 variants on specific sequences. Our results indicate that macroH2As have complex distribution patterns that are influenced by both local factors and long-range mechanisms.

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