scholarly journals Class I Histone Deacetylase Thd1p Promotes Global Chromatin Condensation in Tetrahymena thermophila

2007 ◽  
Vol 6 (10) ◽  
pp. 1913-1924 ◽  
Author(s):  
Kathryn Parker ◽  
Julia Maxson ◽  
Alissa Mooney ◽  
Emily A. Wiley
Keyword(s):  
Histone Deacetylases ◽  
Large Scale ◽  
Tetrahymena Thermophila ◽  
Chromatin Condensation ◽  
Histone H1 ◽  
Class I ◽  
Specific Class ◽  
Chromatin Dynamics ◽  
Core Histones

ABSTRACT Class I histone deacetylases (HDACs) regulate DNA-templated processes such as transcription. They act both at specific loci and more generally across global chromatin, contributing to acetylation patterns that may underlie large-scale chromatin dynamics. Although hypoacetylation is correlated with highly condensed chromatin, little is known about the contribution of individual HDACs to chromatin condensation mechanisms. Using the ciliated protozoan Tetrahymena thermophila, we investigated the role of a specific class I HDAC, Τhd1p, in the reversible condensation of global chromatin. In this system, the normal physiological response to cell starvation includes the widespread condensation of the macronuclear chromatin and general repression of gene transcription. We show that the chromatin in Thd1p-deficient cells failed to condense during starvation. The condensation failure correlated with aberrant hyperphosphorylation of histone H1 and the overexpression of CDC2, encoding the major histone H1 kinase. Changes in the rate of acetate turnover on core histones and in the distribution of acetylated lysines 9 and 23/27 on histone H3 isoforms that were found to correlate with normal chromatin condensation were absent from Thd1p mutant cells. These results point to a role for a class I HDAC in the formation of reversible higher-order chromatin structures and global genome compaction through mechanisms involving the regulation of H1 phosphorylation and core histone acetylation/deacetylation kinetics.

scholarly journals Class I Histone Deacetylase Thd1p Affects Nuclear Integrity in Tetrahymena thermophila

2005 ◽  
Vol 4 (5) ◽  
pp. 981-990 ◽  
Author(s):  
Emily A. Wiley ◽  
Tamara Myers ◽  
Kathryn Parker ◽  
Theodore Braun ◽  
Meng-Chao Yao
Keyword(s):  
Histone Deacetylases ◽  
Nuclear Dna ◽  
Tetrahymena Thermophila ◽  
Nuclear Dna Content ◽  
Class I ◽  
Specific Class ◽  
Acetylation State ◽  
Chromatin Integrity ◽  
Class I Hdacs ◽  
Mutant Cells

ABSTRACT Class I histone deacetylases (HDACs) participate in the regulation of DNA-templated processes such as transcription and replication. Members of this class can act locally at specific sites, or they can act more globally, contributing to a baseline acetylation state, both of which actions may be important for genome maintenance and organization. We previously identified a macronuclear-specific class I HDAC in Tetrahymena thermophila called Thd1p, which is expressed early in the development of the macronucleus when it initially becomes transcriptionally active. To test the idea that Thd1p is important for global chromatin integrity in an active macronucleus, Tetrahymena cells reduced in expression of Thd1p were generated. We observed phenotypes that indicated loss of chromatin integrity in the mutant cells, including DNA fragmentation and extrusion of chromatin from the macronucleus, variable macronuclear size and shape, enlarged nucleoli, and reduced phosphorylation of histone H1 from bulk chromatin. Macronuclei in mutant cells also contained more DNA. This observation suggests a role for Thd1p in the control of nuclear DNA content, a previously undescribed role for class I HDACs. Together, these phenotypes implicate Thd1p in the maintenance of macronuclear integrity in multiple ways, probably through site-specific changes in histone acetylation since no change in the acetylation levels of bulk histones was detected in mutant cells.

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.

A compendium of the histone H1 family of somatic subtypes: An elusive cast of characters and their characteristics

2001 ◽  
Vol 79 (3) ◽  
pp. 289-304 ◽  
Author(s):  
Missag H Parseghian ◽  
Barbara A Hamkalo
Keyword(s):  
Historical Context ◽  
Histone H1 ◽  
General Function ◽  
Linker Histones ◽  
Chromatin Compaction ◽  
The Core ◽  
The Past ◽  
Current State ◽  
Core Histones

The last 35 years has seen a substantial amount of information collected about the somatic H1 subtypes, yet much of this work has been overshadowed by research into highly divergent isoforms of H1, such as H5. Reports from several laboratories in the past few years have begun to call into question some of the traditional views regarding the general function of linker histones and their heterogeneity. Hence, the impression in some circles is that less is known about these ubiquitous nuclear proteins as compared with the core histones. The goal of the following review is to acquaint the reader with the ubiquitous somatic H1s by categorizing them and their characteristics into several classes. The reasons for our current state of misunderstanding is put into a historical context along with recent controversies centering on the role of H1 in the nucleus. Finally, we propose a model that may explain the functional role of H1 heterogeneity in chromatin compaction.Key words: histone H1, linker histones, chromatin organization, chromatin compaction, heat shock.

scholarly journals Transcriptional supercoiling boosts topoisomerase II-mediated knotting of intracellular DNA

2019 ◽  
Vol 47 (13) ◽  
pp. 6946-6955 ◽  
Author(s):  
Antonio Valdés ◽  
Lucia Coronel ◽  
Belén Martínez-García ◽  
Joana Segura ◽  
Sílvia Dyson ◽  
...  
Keyword(s):  
Dna Replication ◽  
Crucial Role ◽  
Topoisomerase Ii ◽  
Chromatin Condensation ◽  
Chromatin Dynamics ◽  
Eukaryotic Chromatin ◽  
Topo Ii ◽  
Inversion Mechanism

AbstractRecent studies have revealed that the DNA cross-inversion mechanism of topoisomerase II (topo II) not only removes DNA supercoils and DNA replication intertwines, but also produces small amounts of DNA knots within the clusters of nucleosomes that conform to eukaryotic chromatin. Here, we examine how transcriptional supercoiling of intracellular DNA affects the occurrence of these knots. We show that although (−) supercoiling does not change the basal DNA knotting probability, (+) supercoiling of DNA generated in front of the transcribing complexes increases DNA knot formation over 25-fold. The increase of topo II-mediated DNA knotting occurs both upon accumulation of (+) supercoiling in topoisomerase-deficient cells and during normal transcriptional supercoiling of DNA in TOP1 TOP2 cells. We also show that the high knotting probability (Pkn ≥ 0.5) of (+) supercoiled DNA reflects a 5-fold volume compaction of the nucleosomal fibers in vivo. Our findings indicate that topo II-mediated DNA knotting could be inherent to transcriptional supercoiling of DNA and other chromatin condensation processes and establish, therefore, a new crucial role of topoisomerase II in resetting the knotting–unknotting homeostasis of DNA during chromatin dynamics.

scholarly journals Role of class I histone deacetylases in the regulation of maspin expression in prostate cancer

2020 ◽  
Vol 59 (8) ◽  
pp. 955-966
Author(s):  
Eswar Shankar ◽  
Mitali Pandey ◽  
Shiv Verma ◽  
Ata Abbas ◽  
Mario Candamo ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Histone Deacetylases ◽  
Class I ◽  
Maspin Expression

The Role of Histone H1 in Chromatin Condensation and Transcriptional Repression

1999 ◽  
pp. 191-204
Author(s):  
Memmo Buttinelli ◽  
Gianna Panetta ◽  
Daniela Rhodes ◽  
Andrew Travers
Keyword(s):  
Transcriptional Repression ◽  
Chromatin Condensation ◽  
Histone H1

The role of histone H1 and non-structured domains of core histones in maintaining the orientation of nucleosomes within the chromatin fiber

1984 ◽  
Vol 122 (3) ◽  
pp. 1021-1027 ◽  
Author(s):  
Vladimir L. Makarov ◽  
Stephan I. Dimitrov ◽  
Irina R. Tsaneva ◽  
Iliya G. Pashev
Keyword(s):  
Histone H1 ◽  
Chromatin Fiber ◽  
Core Histones
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