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  • Histone H4 lysine 20 mono- and tri-methylation define distinct biological processes in SV40 minichromosomes. 20404477

    The methylation profile of histone h4 on lysine 20 in sV40 chromatin during an infection was investigated using ChIp analyses with antibodies to monomethyl (h4K20me1), dimethyl (h4K20me2), and trimethyl (h4K20me3) histone h4. h4K20me1 was found in late-transcribing, uncoating, encapsidating and replicating minichromosomes as well as in the sV40 chromatin present in virions. Its prevalence was greatest in virions and least in minichromosomes present between 4 and 24 hours post-infection. In contrast, h4K20me2 did not appear to be present and h4K20me3 appeared to be present only in minichromosomes obtained 30 minutes post-infection. The presence of h4K20me1 late in infection in replicating minichromosomes and its relative enrichment in virions suggested that it played a role in the encapsidation process. In contrast, the presence of h4K20me3 at the earliest stages of the infection and its subsequent relatively rapid loss along with sV40 chromatin suggested that it was functioning during the uncoating process
    Tipo de documento:
    Referencia
    Referencia del producto:
    07-463
    Nombre del producto:
    Anti-trimethyl-Histone H4 (Lys20) Antibody

  • The human histone gene expression regulator HBP/SLBP is required for histone and DNA synthesis, cell cycle progression and cell proliferation in mitotic cells. 15546920

    Histone proteins are essential for chromatin formation, and histone gene expression is coupled to DNA synthesis. In metazoans, the histone RNA binding protein HBP/SLBP is involved in post-transcriptional control of histone gene expression. In vitro assays have demonstrated that human HBP/SLBP is involved in histone mRNA 3' end formation and translation. We have inhibited human HBP/SLBP expression by RNA interference to determine its function during the mitotic cell cycle. Inhibition of HBP/SLBP expression resulted in the inhibition of histone gene expression and DNA synthesis, the inhibition of cell cycle progression in S phase and the inhibition of cell proliferation. These findings indicate that human HBP/SLBP is essential for the coordinate synthesis of DNA and histone proteins and is required for progression through the cell division cycle.
    Tipo de documento:
    Referencia
    Referencia del producto:
    06-138
    Nombre del producto:
    Anti-Cyclin A Antibody

  • H4K16 acetylation marks active genes and enhancers of embryonic stem cells, but does not alter chromatin compaction. 23990607

    Compared with histone H3, acetylation of H4 tails has not been well studied, especially in mammalian cells. Yet, H4K16 acetylation is of particular interest because of its ability to decompact nucleosomes in vitro and its involvement in dosage compensation in flies. Here we show that, surprisingly, loss of H4K16 acetylation does not alter higher-order chromatin compaction in vivo in mouse embryonic stem cells (ESCs). As well as peaks of acetylated H4K16 and KAT8 histone acetyltransferase at the transcription start sites of expressed genes, we report that acetylation of H4K16 is a new marker of active enhancers in ESCs and that some enhancers are marked by H3K4me1, KAT8, and H4K16ac, but not by acetylated H3K27 or EP300, suggesting that they are novel EP300 independent regulatory elements. Our data suggest a broad role for different histone acetylation marks and for different histone acetyltransferases in long-range gene regulation.
    Tipo de documento:
    Referencia
    Referencia del producto:
    07-329
    Nombre del producto:
    Anti-acetyl-Histone H4 (Lys16) Antibody

  • Histone deacetylases facilitate sodium/calcium exchanger up-regulation in adult cardiomyocytes. 19638401

    It is becoming increasingly evident that histone deacetylases (HDACs) have a prominent role in the alteration of gene expression during the growth remodeling process of cardiac hypertrophy. HDACs are generally viewed as corepressors of gene expression. However, we demonstrate that class I and class II HDACs play an important role in the basal expression and up-regulation of the sodium calcium exchanger (Ncx1) gene in adult cardiomyocytes. Treatment with the HDAC inhibitor trichostatin A (TSA) prevented the pressure-overload-stimulated up-regulation of Ncx1 expression. Overexpression of HDAC5 resulted in the dose-dependent up-regulation of basal and alpha-adrenergic stimulated Ncx1 expression. We show that Nkx2.5 recruits HDAC5 to the Ncx1 promoter, where HDAC5 complexes with HDAC1. Nkx2.5 also interacts with transcriptional activator p300, which is recruited to the Ncx1 promoter. We demonstrate that when Nkx2.5 is acetylated, it is found associated with HDAC5, whereas deacetylated Nkx2.5 is in complex with p300. Notably, TSA treatment prevents p300 from being recruited to the endogenous Ncx1 promoter, resulting in the repression of Ncx1 expression. We propose a novel model for Ncx1 regulation in which deacetylation of Nkx2.5 is required for the recruitment of p300 and results in up-regulation of exchanger expression.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo

  • Asf1 can promote trimethylation of H3 K36 by Set2. 20048053

    Asf1 is a conserved histone H3/H4 chaperone that can assemble and disassemble nucleosomes and promote histone acetylation. Set2 is an H3 K36 methyltransferase. The functions of these proteins intersect in the context of transcription elongation by RNA polymerase II: both contribute to the establishment of repressive chromatin structures that inhibit spurious intragenic transcription. Here we characterize further interactions between budding yeast (Saccharomyces cerevisiae) Asf1 and Set2 using assays of intragenic transcription, H3/H4 posttranslational modification, coding region cross-linking of Asf1 and Set2, and cooccurrence of Asf1 and Set2 in protein complexes. We find that at some genes Asf1 and Set2 control chromatin metabolism as components of separate pathways. However, the existence of a low-abundance complex containing both proteins suggests that Asf1 and Set2 can more directly collaborate in chromatin regulation. Consistent with this possibility, we show that Asf1 stimulates Set2 occupancy of the coding region of a highly transcribed gene by a mechanism that depends on Asf1 binding to H3/H4. This function of Asf1 promotes the switch from di- to trimethylation of H3 K36 at that gene. These results support the view that Set2 function in chromatin metabolism can intimately involve histone chaperone Asf1.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo

  • High histone acetylation and decreased polycomb repressive complex 2 member levels regulate gene specific transcriptional changes during early embryonic stem cell differe ... 17525233

    Histone modifications play a crucial role during embryonic stem (ES) cell differentiation. During differentiation, binding of polycomb repressive complex 2 (PRC2), which mediates trimethylation of lysine 27 on histone H3 (K27me3), is lost on developmental genes that are transcriptionally induced. We observed a global decrease in K27me3 in as little as 3 days after differentiation of mouse ES cells induced by retinoic acid (RA) treatment. The global levels of the histone K27 methyltransferase EZH2 also decreased with RA treatment. A loss of EZH2 binding and K27me3 was observed locally on PRC2 target genes induced after 3 days of RA, including Nestin. In contrast, direct RA-responsive genes that are rapidly induced, such as Hoxa1, showed a loss of EZH2 binding and K27me3 after only a few hours of RA treatment. Following differentiation induced by leukemia inhibitor factor (LIF) withdrawal without RA, Hoxa1 was not transcriptionally activated. Small interfering RNA-mediated knockdown of EZH2 resulted in loss of K27me3 during LIF withdrawal, but the Hoxa1 gene remained transcriptionally silent after loss of this repressive mark. Induction of histone hyperacetylation overrode the repressive K27me3 modification and resulted in Hoxa1 gene expression. Together, these data show that there are multiple temporal phases of derepression of PRC2 target genes during ES cell differentiation and that other epigenetic marks (specifically, increased acetylation of histones H3 and H4), in addition to derepression, are important for gene-specific transcriptional activation. This report demonstrates the temporal interplay of various epigenetic changes in regulating gene expression during early ES cell differentiation.
    Tipo de documento:
    Referencia
    Referencia del producto:
    3301

  • Melatonin induces histone hyperacetylation in the rat brain. 23416321

    We have reported that melatonin induces histone hyperacetylation in mouse neural stem cells, suggesting an epigenetic role for this pleiotropic hormone. To support such a role, it is necessary to demonstrate that melatonin produces similar effects in vivo. Histone acetylation, following chronic treatment with melatonin (4μg/ml in drinking water for 17 days), was examined by western blotting in selected rat brain regions. Melatonin induced significant increases in histone H3 and histone H4 acetylation in the hippocampus. Histone H4 was also hyperacetylated in the striatum, but there were no significant changes in histone H3 acetylation in this brain region. No significant changes in the acetylation of either histone H3 or H4 were observed in the midbrain and cerebellum. An examination of kinase activation, which may be related to these changes, revealed that melatonin treatment increased the levels of phospho-ERK (extracellular signal-regulated kinase) in the hippocampus and striatum, but phospho-Akt (protein kinase B) levels were unchanged. These findings suggest that chromatin remodeling and associated changes in the epigenetic regulation of gene expression underlie the multiple physiological effects of melatonin.
    Tipo de documento:
    Referencia
    Referencia del producto:
    07-593

  • HDA6 directly interacts with DNA methyltransferase MET1 and maintains transposable element silencing in Arabidopsis. 21994348

    The molecular mechanism of how the histone deacetylase HDA6 participates in maintaining transposable element (TE) silencing in Arabidopsis (Arabidopsis thaliana) is not yet defined. In this study, we show that a subset of TEs was transcriptionally reactivated and that TE reactivation was associated with elevated histone H3 and H4 acetylation as well as increased H3K4Me3 and H3K4Me2 in hda6 mutants. Decreased DNA methylation of the TEs was also detected in hda6 mutants, suggesting that HDA6 silences the TEs by regulating histone acetylation and methylation as well as the DNA methylation status of the TEs. Similarly, transcripts of some of these TEs were also increased in the methyltransferase1 (met1) mutant, with decreased DNA methylation. Furthermore, H4 acetylation, H3K4Me3, H3K4Me2, and H3K36Me2 were enriched at the coregulated TEs in the met1 and hda6 met1 mutants. Protein-protein interaction analysis indicated that HDA6 physically interacts with MET1 in vitro and in vivo, and further deletion analysis demonstrated that the carboxyl-terminal region of HDA6 and the bromo-adjacent homology domain of MET1 were responsible for the interaction. These results suggested that HDA6 and MET1 interact directly and act together to silence TEs by modulating DNA methylation, histone acetylation, and histone methylation status.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo

  • Schizosaccharomyces pombe Hat1 (Kat1) is associated with Mis16 and is required for telomeric silencing. 22771823

    The Hat1 histone acetyltransferase has been implicated in the acetylation of histone H4 during chromatin assembly. In this study, we have characterized the Hat1 complex from the fission yeast Schizosaccharomyces pombe and have examined its role in telomeric silencing. Hat1 is found associated with the RbAp46 homologue Mis16, an essential protein. The Hat1 complex acetylates lysines 5 and 12 of histone H4, the sites that are acetylated in newly synthesized H4 in a wide range of eukaryotes. Deletion of hat1 in S. pombe is itself sufficient to cause the loss of silencing at telomeres. This is in contrast to results obtained with an S. cerevisiae hat1Δ strain, which must also carry mutations of specific acetylatable lysines in the H3 tail domain for loss of telomeric silencing to occur. Notably, deletion of hat1 from S. pombe resulted in an increase of acetylation of histone H4 in subtelomeric chromatin, concomitant with derepression of this region. A similar loss of telomeric silencing was also observed after growing cells in the presence of the deacetylase inhibitor trichostatin A. However, deleting hat1 did not cause loss of silencing at centromeres or the silent mating type locus. These results point to a direct link between Hat1, H4 acetylation, and the establishment of repressed telomeric chromatin in fission yeast.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo

  • Efficient organic monoliths prepared by γ-radiation induced polymerization in the evaluation of histone deacetylase inhibitors by capillary(nano)-high performance liquid ... 21561626

    New monolithic HPLC columns were prepared by γ-radiation-triggered polymerization of hexyl methacrylate and ethylene glycol dimethacrylate monomers in the presence of porogenic solvents. Polymerization was carried out directly within capillary (250-200μm I.D.) and nano (100-75μm I.D.) fused-silica tubes yielding highly efficient columns for cap(nano)-LC applications. The columns were applied in the complete separation of core (H2A, H2B, H3, and H4) and linker (H1) histones under gradient elution with UV and/or electrospray ionization (ESI) ion trap mass spectrometry (MS) detections. Large selectivity towards H1, H2A-1, H2A-2, H2B, H3-1, H3-2 and H4 histones and complete separation were obtained within 8min time windows, using fast gradients and very high linear flow velocities, up to 11mm/s for high throughput applications. The method developed was the basis of a simple and efficient protocol for the evaluation of post-translational modifications (PTMs) of histones from NCI-H460 human non-small-cell lung cancer (NSCLC) and HCT-116 human colorectal carcinoma cells. The study was extended to monitoring the level of histone acetylation after inhibition of Histone DeACetylase (HDAC) enzymes with suberoylanilide hydroxamic acid (SAHA), the first HDAC inhibitor approved by the FDA for cancer therapy. Attractive features of our cap(nano)-LC/MS approach are the short analysis time, the minute amount of sample required to complete the whole procedure and the stability of the polymethacrylate-based columns. A lab-made software package ClustMass was ad hoc developed and used to elaborate deconvoluted mass spectral data (aligning, averaging, clustering) and calculate the potency of HDAC inhibitors, expressed through a Relative half maximal Inhibitory Concentration parameter, namely R_IC(50) and an averaged acetylation degree.Copyright © 2011 Elsevier B.V. All rights reserved.
    Tipo de documento:
    Referencia
    Referencia del producto:
    Múltiplo
    Nombre del producto:
    Múltiplo