Project description:Post-translational modifications (PTMs) of proteins, such as acetylation or phosphorylation, represent a huge untapped source of targets of great biological and therapeutic potential, but their validation can only be indirect. PTMs cannot be selectively hit by the powerful nucleic-acid based interference approaches. Antibodies represent a class of molecules that could be exploited to selectively target PTMs. However, currently it is not possible to systematically derive antibodies that selectively bind PTMs of a native protein and work intracellularly to achieve a native PTM-selective interference. We developed the Post-translational Intracellular Silencing Antibody technology (P.I.S.A.), a new method for the selection of intrabodies targeting the native PTM version of proteins and their use for PTM targeting in cells. We used PISA to select an intrabody against acetylated-K9-H3 Histone (ScFv-58F). Microarray study is aimed at the investigation of ScFv-58F-specific changes in gene expression in yeast, in comparison to yeast expressing a control intrabody (ScFv-112A, anti-acetyl-Integrase, selected with PISA), and to a wild type yeast.
Project description:ChIP-chip assays to determine the occupancy of acetylated histone H3 K56 in wildtype, isw1, chd1, isw1 chd1 and ISW1[K227R] yeast. Two color experiment. ChIP/Input. K56ac data normalized to histone H3 and plotted as mutant over wildtype. Biological replicates=3. Please note that H3 data for YMS123-125 & YMS127 is part of the AcH4 file.
Project description:Whole genome ChIP-chip study using human liver cell line HepG2 and anti-Histone H3 acetyl K9/14 (06-599); USF1 antibody (H-86, sc-8983); USF2 antibody (C-20, sc-862) and normal rabbit IgG (12-370). Three completely independent biological replicates were performed for each antibody, obtaining the corresponding input as total genomic DNA reference. Hybridizations were performed using Affymetrix GeneChip Human Tiling 2.0R Array set (7 arrays set).
Project description:Histone H3 lysine 4 tri-methylation (H3K4me3) is a hallmark of transcription initiation, but how H3K4me3 is demethylated during gene repression is poorly understood. Jhd2, a JmjC domain protein, was recently identified as the major H3K4me3 histone demethylase (HDM) in S. cerevisiae. While JHD2 is required for removal of methylation upon gene repression, deletion of JHD2 does not result in increased levels of H3K4me3 in bulk histones, indicating that this HDM is unable to demethylate histones during steady state conditions. In this study, we showed that this was due to the negative regulation of Jhd2 activity by histone H3 lysine 14 acetylation, which co-localizes with H3K4me3 across the yeast genome. We demonstrated that loss of the histone H3-specific acetyltransferases (HATs) resulted in genome-wide-depletion of H3K4me3, and this was not due to a transcription defect. Moreover, H3K4me3 levels were reestablished in HAT mutants following loss of JHD2, which suggested that H3-specific HATs and Jhd2 served opposing functions in regulating H3K4me3 levels. We revealed the molecular basis for this suppression by demonstrating that histone H3K14 acetylation negatively regulated Jhd2 demethylase activity on an acetylated peptide in vitro. These results revealed the existence of a general mechanism for removal of H3K4me3 following gene repression. Examination of H3K4me3 in WT, ada2sas3, ada2sas3jhd2, and jhd2 strains.
Project description:Histone acetylation is a major epigenetic control mechanism that is tightly linked to the promotion of gene expression. Histone acetylation levels are balanced through the opposing activities of histone acetyltransferases (HATs) and histone deacetylases (HDACs). Arabidopsis HDAC genes (AtHDACs) compose a large gene family, and distinct phenotypes among AtHDAC mutants reflect the functional specificity of individual AtHDACs. However, the mechanisms underlying this functional diversity are largely unknown. Here, we show that POWERDRESS (PWR), a positive regulator of floral stem cell maintenance, interacts with HDA9 and promotes histone H3 deacetylation possibly by facilitating HDA9 function at target chromatin. The PWR SANT2 domain, which is homologous to that of subunits in animal HDAC complexes, showed specific binding affinity to acetylated histone H3. Three lysine residues (K9, K14 and K27) of H3 retained hyperacetylation status in both pwr and hda9 mutants. Genome wide H3K9 and H3K14 acetylation levels were generally elevated, and a large portion of acetylated targets overlapped between the pwr and hda9 mutants. Comparative analysis revealed a correlation between gene expression and histone H3 acetylation status in the pwr and hda9 mutants. In addition, PWR and HDA9 modulated the AGAMOUS-LIKE 19 (AGL19)-mediated flowering time pathway through histone H3 deacetylation. Finally, PWR was shown to physically interact with HDA9. We therefore propose that PWR acts as a subunit in a complex with HDA9 to negatively regulate the acetylation of specific lysine residues of histone H3 at genomic targets.
Project description:Histone acetylation is a major epigenetic control mechanism that is tightly linked to the promotion of gene expression. Histone acetylation levels are balanced through the opposing activities of histone acetyltransferases (HATs) and histone deacetylases (HDACs). Arabidopsis HDAC genes (AtHDACs) compose a large gene family, and distinct phenotypes among AtHDAC mutants reflect the functional specificity of individual AtHDACs. However, the mechanisms underlying this functional diversity are largely unknown. Here, we show that POWERDRESS (PWR), a positive regulator of floral stem cell maintenance, interacts with HDA9 and promotes histone H3 deacetylation possibly by facilitating HDA9 function at target chromatin. The PWR SANT2 domain, which is homologous to that of subunits in animal HDAC complexes, showed specific binding affinity to acetylated histone H3. Three lysine residues (K9, K14 and K27) of H3 retained hyperacetylation status in both pwr and hda9 mutants. Genome wide H3K9 and H3K14 acetylation levels were generally elevated, and a large portion of acetylated targets overlapped between the pwr and hda9 mutants. Comparative analysis revealed a correlation between gene expression and histone H3 acetylation status in the pwr and hda9 mutants. In addition, PWR and HDA9 modulated the AGAMOUS-LIKE 19 (AGL19)-mediated flowering time pathway through histone H3 deacetylation. Finally, PWR was shown to physically interact with HDA9. We therefore propose that PWR acts as a subunit in a complex with HDA9 to negatively regulate the acetylation of specific lysine residues of histone H3 at genomic targets.
Project description:Histone H3 lysine 4 tri-methylation (H3K4me3) is a hallmark of transcription initiation, but how H3K4me3 is demethylated during gene repression is poorly understood. Jhd2, a JmjC domain protein, was recently identified as the major H3K4me3 histone demethylase (HDM) in S. cerevisiae. While JHD2 is required for removal of methylation upon gene repression, deletion of JHD2 does not result in increased levels of H3K4me3 in bulk histones, indicating that this HDM is unable to demethylate histones during steady state conditions. In this study, we showed that this was due to the negative regulation of Jhd2 activity by histone H3 lysine 14 acetylation, which co-localizes with H3K4me3 across the yeast genome. We demonstrated that loss of the histone H3-specific acetyltransferases (HATs) resulted in genome-wide-depletion of H3K4me3, and this was not due to a transcription defect. Moreover, H3K4me3 levels were reestablished in HAT mutants following loss of JHD2, which suggested that H3-specific HATs and Jhd2 served opposing functions in regulating H3K4me3 levels. We revealed the molecular basis for this suppression by demonstrating that histone H3K14 acetylation negatively regulated Jhd2 demethylase activity on an acetylated peptide in vitro. These results revealed the existence of a general mechanism for removal of H3K4me3 following gene repression.
Project description:Normal cell type specific histone H3 acetylation of miRNA genes. HMEC and HMF represent two distinct differentiated cell type present in mammary gland each with a distinct phenotype, a distinct epigenotype as well as distinct miRNA expression pattern. The aim of the study was to determine how epigenetic modifications including histone H3 acetylation affect miRNA expression. Two cell types HMEC vs. HMF. Biological replicates: 3 pairs of HMEC-HMF of 3 distinct genotypes. Immunoprecipitation using anti-acetylated histone H3 antibody (06-599, Millipore).
Project description:Acetylation of histone H3 at residue K9 (H3K9ac) is a dynamically regulated mark associated with transcriptionally active promoters in eukaryotes. However, our understanding of the relation-ship between H3K9ac and gene expression remains largely correlative. In this study, we identify a large suite of growth-related genes in yeast that undergo a particularly strong down-regulation of both transcription and H3K9ac upon stress, and delineate the roles of transcriptional activa-tors, repressors, SAGA histone acetyltransferase, and RNA-polymerase II in this response. We demonstrate that H3K9 acetylation states are orchestrated by a two-step mechanism driven by the dynamic binding of transcriptional repressors and activators, that is independent of tran-scription. In response to stress, promoter release of transcriptional activators at growth-related genes is a prerequisite for rapid reduction of H3K9ac, whereas binding of transcriptional re-pressors is required to establish a hypo-acetylated, strongly repressed state.