The Experts below are selected from a list of 249 Experts worldwide ranked by ideXlab platform
Hermann Hecker - One of the best experts on this subject based on the ideXlab platform.
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properties of the Histones and functional aspects of the soluble chromatin of epimastigote trypanosoma cruzi
Acta Tropica, 1995Co-Authors: Wolfram Schlimme, Markus Burri, Bruno Betschart, Hermann HeckerAbstract:The amino acid composition of all Histones of Trypanosoma cruzi was analyzed, and the terminology of the Histones of higher eukaryotes adopted. One chromatin associated protein, previously considered to be a variant of Histone H1, could not be clearly identified, and shows features of core Histones as well as of Histone H1. An improved method for the isolation of intact nuclei and the production of soluble chromatin in T. cruzi was established. The chromatin of T. cruzi is relatively instable and Histone H1 is easily lost during experimental manipulations. Histone H1 dissociates completely at a relatively low NaCl concentration of 380 mM, leading to an open nucleosome filament which does not condense. The influence of Histone H1 of T. cruzi and of rat liver on the compaction pattern of the chromatin was investigated by homologous and heterologous reconstitution experiments, and analysed by electron microscopy. It could be shown that Histone H1 of T. cruzi induces nucleosome filaments of T. cruzi as well as those of rat liver to condense. The same is true for Histone H1 of rats. It can be concluded that T. cruzi has a functional Histone H1.
Tony Kouzarides - One of the best experts on this subject based on the ideXlab platform.
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Histone core modifications regulating nucleosome structure and dynamics
Nature Reviews Molecular Cell Biology, 2014Co-Authors: Peter Tessarz, Tony KouzaridesAbstract:Recent data suggest that Histone modifications have a direct effect on nucleosomal architecture. Acetylation, methylation, phosphorylation and citrullination of the Histone core may influence chromatin structure by affecting Histone–Histone and Histone–DNA interactions, as well as the binding of Histones to chaperones.
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Reversing Histone methylation
Nature, 2005Co-Authors: Andrew J. Bannister, Tony KouzaridesAbstract:Histones package DNA, and post-translational modifications of Histones can regulate access to DNA. Until recently, Histone methylation-unlike all other Histone modifications-was considered a permanent mark. The discovery of enzymes that reverse the methylation of lysines and arginines challenges our current thinking on the unique nature of Histone methylation, and substantially increases the complexity of Histone modification pathways.
Geneviève Almouzni - One of the best experts on this subject based on the ideXlab platform.
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JMJD1B, a novel player in Histone H3 and H4 processing to ensure genome stability
Epigenetics & Chromatin, 2020Co-Authors: Francisco Saavedra, Geneviève Almouzni, Zachary Gurard-levin, Camila Rojas-villalobos, Isabelle Vassias, Raquel Quatrini, Alejandra LoyolaAbstract:BACKGROUND: Maintaining a proper supply of soluble Histones throughout the cell cycle is important to ensure chromatin and genome stability. Following their synthesis, Histones undergo a series of maturation steps to prepare them for deposition onto chromatin. RESULTS: Here, we identify the lysine demethylase JMJD1B as a novel player in the maturation cascade that contributes to regulate Histone provision. We find that depletion of JMJD1B increases the protein levels of the Histone chaperone tNASP leading to an accumulation of newly synthesized Histones H3 and H4 at early steps of the Histone maturation cascade, which perturbs chromatin assembly. Furthermore, we find a high rate of JMJD1B mutations in cancer patients, and a correlation with genomic instability. CONCLUSIONS: Our data support a role for JMJD1B in fine-tuning Histone supply to maintain genome integrity, opening novel avenues for cancer therapeutics.
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Histone Chaperones: Assisting Histone Traffic and Nucleosome Dynamics
Annual Review of Biochemistry, 2014Co-Authors: Zachary A. Gurard-levin, Jean-pierre Quivy, Geneviève AlmouzniAbstract:The functional organization of eukaryotic DNA into chromatin uses Histones as components of its building block, the nucleosome. Histone chaperones, which are proteins that escort Histones throughout their cellular life, are key actors in all facets of Histone metabolism; they regulate the supply and dynamics of Histones at chromatin for its assembly and disassembly. Histone chaperones can also participate in the distribution of Histone variants, thereby defining distinct chromatin landscapes of importance for genome function, stability, and cell identity. Here, we discuss our current knowledge of the known Histone chaperones and their Histone partners, focusing on Histone H3 and its variants. We then place them into an escort network that distributes these Histones in various deposition pathways. Through their distinct interfaces, we show how they affect dynamics during DNA replication, DNA damage, and transcription, and how they maintain genome integrity. Finally, we discuss the importance of Histone chaperones during development and describe how misregulation of the Histone flow can link to disease.
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Histone chaperones: an escort network regulating Histone traffic
Nature Structural & Molecular Biology, 2007Co-Authors: Leanne De Koning, Armelle Corpet, James E Haber, Geneviève AlmouzniAbstract:In eukaryotes, DNA is organized into chromatin in a dynamic manner that enables it to be accessed for processes such as transcription and repair. Histones, the chief protein component of chromatin, must be assembled, replaced or exchanged to preserve or change this organization according to cellular needs. Histone chaperones are key actors during Histone metabolism. Here we classify known Histone chaperones and discuss how they build a network to escort Histone proteins. Molecular interactions with Histones and their potential specificity or redundancy are also discussed in light of chaperone structural properties. The multiplicity of Histone chaperone partners, including Histone modifiers, nucleosome remodelers and cell-cycle regulators, is relevant to their coordination with key cellular processes. Given the current interest in chromatin as a source of epigenetic marks, we address the potential contributions of Histone chaperones to epigenetic memory and genome stability.
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Histone h3 1 and h3 3 complexes mediate nucleosome assembly pathways dependent or independent of dna synthesis
Cell, 2004Co-Authors: Hideaki Tagami, Geneviève Almouzni, Dominique Raygallet, Yoshihiro NakataniAbstract:Deposition of the major Histone H3 (H3.1) is coupled to DNA synthesis during DNA replication and possibly DNA repair, whereas Histone variant H3.3 serves as the replacement variant for the DNA-synthesis-independent deposition pathway. To address how Histones H3.1 and H3.3 are deposited into chromatin through distinct pathways, we have purified deposition machineries for these Histones. The H3.1 and H3.3 complexes contain distinct Histone chaperones, CAF-1 and HIRA, that we show are necessary to mediate DNA-synthesis-dependent and -independent nucleosome assembly, respectively. Notably, these complexes possess one molecule each of H3.1/H3.3 and H4, suggesting that Histones H3 and H4 exist as dimeric units that are important intermediates in nucleosome formation. This finding provides new insights into possible mechanisms for maintenance of epigenetic information after chromatin duplication.
Wolfram Schlimme - One of the best experts on this subject based on the ideXlab platform.
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properties of the Histones and functional aspects of the soluble chromatin of epimastigote trypanosoma cruzi
Acta Tropica, 1995Co-Authors: Wolfram Schlimme, Markus Burri, Bruno Betschart, Hermann HeckerAbstract:The amino acid composition of all Histones of Trypanosoma cruzi was analyzed, and the terminology of the Histones of higher eukaryotes adopted. One chromatin associated protein, previously considered to be a variant of Histone H1, could not be clearly identified, and shows features of core Histones as well as of Histone H1. An improved method for the isolation of intact nuclei and the production of soluble chromatin in T. cruzi was established. The chromatin of T. cruzi is relatively instable and Histone H1 is easily lost during experimental manipulations. Histone H1 dissociates completely at a relatively low NaCl concentration of 380 mM, leading to an open nucleosome filament which does not condense. The influence of Histone H1 of T. cruzi and of rat liver on the compaction pattern of the chromatin was investigated by homologous and heterologous reconstitution experiments, and analysed by electron microscopy. It could be shown that Histone H1 of T. cruzi induces nucleosome filaments of T. cruzi as well as those of rat liver to condense. The same is true for Histone H1 of rats. It can be concluded that T. cruzi has a functional Histone H1.
Charles T Esmon - One of the best experts on this subject based on the ideXlab platform.
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extracellular Histones are mediators of death through tlr2 and tlr4 in mouse fatal liver injury
Journal of Immunology, 2011Co-Authors: Jun Xu, Xiaomei Zhang, Marc Monestier, Naomi L Esmon, Charles T EsmonAbstract:We previously reported that extracellular Histones are major mediators of death in sepsis. Infusion of extracellular Histones leads to increased cytokine levels. Histones activate TLR2 and TLR4 in a process that is enhanced by binding to DNA. Activation of TLR4 is responsible for the Histone-dependent increase in cytokine levels. To study the impact of Histone release on pathology we used two models: a Con A-triggered activation of T cells to mimic sterile inflammation, and acetaminophen to model drug-induced tissue toxicity. Histones were released in both models and anti-Histone Abs were protective. TLR2- or TLR4-null mice were also protected. These studies imply that Histone release contributes to death in inflammatory injury and in chemical-induced cellular injury, both of which are mediated in part through the TLRs.
