scholarly journals Unravelling the Role of Linker Histone H1 and the H4-Tail in Chromatin (Un-)Folding

2016 ◽  
Vol 110 (3) ◽  
pp. 68a
Author(s):  
Artur Kaczmarczyk ◽  
Kim Vendel ◽  
Abdollah Allahverdi ◽  
Lars Nordenskiöld ◽  
Nynke H. Dekker ◽  
...  
Keyword(s):  
Histone H1 ◽  
Linker Histone ◽  
Linker Histone H1

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 Histone H1 is essential for mitotic chromosome architecture and segregation in Xenopus laevis egg extracts

2005 ◽  
Vol 169 (6) ◽  
pp. 859-869 ◽  
Author(s):  
Thomas J. Maresca ◽  
Benjamin S. Freedman ◽  
Rebecca Heald
Keyword(s):  
Xenopus Laevis ◽  
Metaphase Plate ◽  
Histone H1 ◽  
Linker Histone ◽  
Chromosome Architecture ◽  
Linker Histone H1 ◽  
Egg Extracts ◽  
Chromatin Proteins ◽  
And Function

During cell division, condensation and resolution of chromosome arms and the assembly of a functional kinetochore at the centromere of each sister chromatid are essential steps for accurate segregation of the genome by the mitotic spindle, yet the contribution of individual chromatin proteins to these processes is poorly understood. We have investigated the role of embryonic linker histone H1 during mitosis in Xenopus laevis egg extracts. Immunodepletion of histone H1 caused the assembly of aberrant elongated chromosomes that extended off the metaphase plate and outside the perimeter of the spindle. Although functional kinetochores assembled, aligned, and exhibited poleward movement, long and tangled chromosome arms could not be segregated in anaphase. Histone H1 depletion did not significantly affect the recruitment of known structural or functional chromosomal components such as condensins or chromokinesins, suggesting that the loss of H1 affects chromosome architecture directly. Thus, our results indicate that linker histone H1 plays an important role in the structure and function of vertebrate chromosomes in mitosis.

Abstract 199: Distinctive Roles of Linker Histone H1 Variants in the Hypertrophic Response of Cardiomyocytes

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Michelle S Parvatiyar ◽  
Timothy D Lopez ◽  
Sarah Franklin ◽  
Thomas M Vondriska
Keyword(s):  
Histone H1 ◽  
Histone Variants ◽  
Linker Histone ◽  
Neonatal Rat ◽  
Cardiomyocyte Hypertrophy ◽  
Mrna Levels ◽  
Hypertrophic Response ◽  
Linker Histone H1 ◽  
Knock Down

Heart failure results when cardiac output is insufficient to meet physiological requirements and is often preceded by development of cardiomyocyte hypertrophy. As cardiac myocytes respond to hypertrophic stresses they re-express developmentally important genes, normally senescent in the adult. The chromatin structural events underlying this “fetal gene program” are unknown. We previously showed by proteomics that histones, components of the chromatin protein functional unit, the nucleosome, are altered during hypertrophic and failing phases of pressure overload in mouse: linker histone variants H1.2 and H1.5 decreased in hypertrophied myocardium while H1.0 increased during the transition to failure. The linker histone H1 family influences higher order chromatin structure and gene expression, although the role of this family in the heart is unknown. To assess the role of linker histones in hypertrophy, neonatal rat ventricular cardiomyocytes (NRVMs) were transfected with siRNAs individually targeting six H1 variants. Loss of H1.3 and H1.4 respectively induced a significant 26.1% (76 of 90) and 13.5% (80 of 94) increase in cell size area (µm2). A role of H1 in the hypertrophic response is evidenced by its influence on myosin heavy chain (MHC) mRNA expression. Knock-down of individual H1 variants significantly altered the MHC isoform ratio: loss of H1.3 increased α-MHC levels 1.5 fold and decreased β-MHC 1.6 fold while H1.5 depletion decreased α-MHC 2.5 fold. Both H1.3 and H1.4 knock-down increased atrial natriuretic factor (ANF) 1.3 fold while H1.5 loss decreased ANF 6.2 fold shown by qRT-PCR. Treatment with hypertrophy-inducing agents Isoproterenol (1μM), Endothelin (2nM) or Phenylephrine (10μM), reduced H1 mRNA levels however with subtle effects on protein abundance. To evaluate whether H1 loss shifted NRVM nuclei from a predominantly heterochromatic toward euchromatic state favoring gene accessibility we examined distinct histone markers of chromatin states. Histone H1.5 knock-down significantly decreased H3K9Me3 levels, a silencing mark associated with heterochromatin, 1.7 fold. Therefore we conclude that variants package distinctive regions of the genome and that H1.3 and H1.4 controls genes involved in the hypertrophic response.

scholarly journals The histone variant H2A.W and linker histone H1 co-regulate heterochromatin accessibility and DNA methylation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Pierre Bourguet ◽  
Colette L. Picard ◽  
Ramesh Yelagandula ◽  
Thierry Pélissier ◽  
Zdravko J. Lorković ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Histone H1 ◽  
Epigenetic Modifications ◽  
Flowering Plants ◽  
Linker Histone ◽  
Histone Variant ◽  
Null Mutant ◽  
Chromatin Compaction ◽  
Linker Histone H1

AbstractIn flowering plants, heterochromatin is demarcated by the histone variant H2A.W, elevated levels of the linker histone H1, and specific epigenetic modifications, such as high levels of DNA methylation at both CG and non-CG sites. How H2A.W regulates heterochromatin organization and interacts with other heterochromatic features is unclear. Here, we create a h2a.w null mutant via CRISPR-Cas9, h2a.w-2, to analyze the in vivo function of H2A.W. We find that H2A.W antagonizes deposition of H1 at heterochromatin and that non-CG methylation and accessibility are moderately decreased in h2a.w-2 heterochromatin. Compared to H1 loss alone, combined loss of H1 and H2A.W greatly increases accessibility and facilitates non-CG DNA methylation in heterochromatin, suggesting co-regulation of heterochromatic features by H2A.W and H1. Our results suggest that H2A.W helps maintain optimal heterochromatin accessibility and DNA methylation by promoting chromatin compaction together with H1, while also inhibiting excessive H1 incorporation.

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.

Quantitative Assessment of Transition Proteins 1, 2 Spermatid-Specific Linker Histone H1-Like Protein Transcripts in Spermatozoa from Normozoospermic and Asthenozoospermic Men

2007 ◽  
Vol 53 (4) ◽  
pp. 199-205 ◽  
Author(s):  
Piotr Jedrzejczak ◽  
Bartosz Kempisty ◽  
Artur Bryja ◽  
M. Mostowska ◽  
Magdalena Depa-Martynow ◽  
...  
Keyword(s):  
Quantitative Assessment ◽  
Histone H1 ◽  
Linker Histone ◽  
Linker Histone H1
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