Epigenomic Signatures of Neuronal Diversity in the Mammalian Brain
Ontology highlight
ABSTRACT: We developed an affinity purification approach to isolate tagged nuclei in mice (similar to INTACT; [Deal R.B. and Henikoff S. A simple method for gene expression and chromatin profiling of individual cell types within a tissue. Dev. Cell 18,1030-1040. (2010)]) and used it to characterize genome-wide patterns of transcription, DNA methylation, and chromatin accessibility in 3 major neuron classes of the neocortex (excitatory pyramidal neurons, parvalbumin (PV)-positive GABAergic interneurons, and vasoactive intestinal peptide (VIP)-positive GABAergic interneurons). By combining cell purification and integrative analysis, our findings relate the phenotypic and functional complexity of neocortical neurons to their underlying transcriptional and epigenetic diversity. RNA-seq, MethylC-seq, ATAC-seq, and ChIP-seq for histone modifications using INTACT-purified nuclei from the mouse neocortex
Project description:Chromatin profiling of nuclei isolated from genetically defined neuronal subpopulations of the adult Drosophila brain. Cell type-specific histone modification maps were generated from nuclei isolated from all neurons (R57C10-GAL4), Kenyon cells (OK107-GAL4), and octopaminergic (Tdc2-GAL4) neurons using a method similar to INTACT (Deal and Henikoff, 2010; Steinner et al., 2012). Three histone modifications were profiled: H3K4me3, H3K27ac, and H3K27me3. Sequencing was performed with an Illumina HiSeq 2000.
Project description:This SuperSeries is composed of the following subset Series: GSE37027: Cell type-specific gene expression profiling of Drosophila neurons [RNA-Seq] GSE37032: Cell type-specific chromatin profiling of Drosophila neurons [ChIP-Seq] Refer to individual Series
Project description:We characterize the acetylation of H3K122 for the first time. Towards this we mapped the genomic distribution of H3K122Ac, identified the enzyme introducing H3K122Ac, and addressed the functional contribution H3K122Ac to transcription. We found that H3K122Ac is associated with chromatin marks and genomic regions associated with active transcription and is catalysed by p300/CBP and can be regulated by estrogen signaling in MCF-7. Moreover H3K122Ac stimulates transcription as dermined by in vitro transcription assays ChIP seq study
Project description:To investigate how dSETDB1 regulated the genome-wide distribution of HP1 proteins, we performed ChIP-chip assay on the third instar larval lysate from the dSETDB1null mutants in comparison to the wild type. Third instar larvae from the wild type and dSETDB1null mutants were collected. Three independent biological replicates of ChIP with anti-HP1 were performed.
Project description:We were interested to explain why p53 binds some high affinity sites in contrast to other high affinity sites that are not bound by p53. p53 binding was measured using p53 ChIP-CHIP and in parallel nucleosome occupancy was measured on these same sites Comparison between p53 binding and nucleosome occupancy at p53 predicted binding sites ChIP-CHIP of p53 from MCF7EcoR under Basal conditions and MCF7EcoR treated with NCS (Activated) and Mononucleosomal extraction from MCF7sip53, MCF7EcoR under Basal conditions and MCF7EcoR treated with NCS (Activated) Expression analysis of MCF7sip53 and MCF7EcoR treated with NCS (Activated)
Project description:Drosophila PBAP complex, a form of SWI/SNF class of complexes, played a important role in metamorphosis. We conducted MNase digestion followed by next-generation sequencing (NGS) to analyse the nucleosome profile in both control and Brm knockdown fly larvae.
Project description:The INO80 complex is a chromatin remodeler that regulates DNA replication, repair, and transcription. Although the INO80 complex plays a crucial role in various chromatin-associated processes, the mechanism of its recruitment to specific genomic loci is not well understood. Here we used a native ChIP-MS approach to quantitatively profile modifications present on nucleosomes co-purified with INO80 from MNAse-digested HeLa chromatin.
Project description:Over the past decades, protein O-GlcNAcylation has been found to play a fundamental role in cell cycle control, metabolism, transcriptional regulation, and cellular signaling. Nevertheless, quantitative approaches to determine in vivo GlcNAc dynamics at a large-scale are still not readily available. Here, we have developed an approach to isotopically label O-GlcNAc modifications on proteins by producing 13C-labeled UDP-GlcNAc from 13C6-glucose via the hexosamine biosynthetic pathway. This metabolic labeling was combined with quantitative mass spectrometry-based proteomics to determine site-specific protein O-GlcNAcylation turnover rates. First, an efficient enrichment method for O-GlcNAc peptides was developed with the use of phenylboronic acid solid-phase extraction and anhydrous DMSO. The near stoichiometry reaction between the diol of GlcNAc and boronic acid dramatically improved the enrichment efficiency. Additionally, our kinetic model for turnover rates integrates both metabolomic and proteomic data, which increase the accuracy of the turnover rate estimation. Other advantages of this metabolic labeling method include in vivo application, direct labeling of the O-GlcNAc sites and higher confidence for site identification. Concentrating only on nuclear localized GlcNAc modified proteins, we are able to identify 159 O-GlcNAc sites on 74 proteins and determine turnover rates of 24 O-GlcNAc peptides from 21 proteins extracted from HeLa nuclei. In general, we found O-GlcNAcylation turnover rates are slower than those published for phosphorylation or acetylation. Nevertheless, the rates widely varied depending on both the protein and the residue modified. We believe this methodology can be broadly applied to reveal turnovers/dynamics of protein O-GlcNAcylation from different biological states and will provide more information on the significance of site-specific O-GlcNAcylation, enabling us to study the temporal dynamics of this critical modification in a site-specific manner for the first time.
Project description:Chromatin transactions are typically studied in vivo, or in vitro using artificial chromatin lacking the epigenetic complexity of the natural material. Attempting to bridge the gap between these approaches, we established a system for isolating the yeast genome as a library of mono-nucleosomes harbouring the natural epigenetic signature, suitable for biochemical manipulation. Combined with deep sequencing, this library was used to investigate the stability of individual nucleosomes, and – as proof of principle - the nucleosome preference of the chromatin remodeling complex, RSC. In order to generate a library of native yeast nucleosomes, we developed a three-step purification protocol: first, purified yeast nuclei were incubated with micrococcal nuclease (MNase), which preferentially digests naked DNA to generate short chromatin fragments. The resulting fragments were extracted from the nuclei, then bound to and eluted from DEAE sepharose. This was followed by ultracentrifugation through a sucrose gradient to separate the fragments by length to further remove contaminating proteins and free DNA. We chose a simple disassembly assay, which involves incubating the nucleosome library with ATP and the histone chaperone Nap1, with or without RSC. In this assay, RSC binds to nucleosomes and transfers the histones to Nap1, thereby releasing ‘naked’ DNA. Under certain conditions, reaction intermediates can be observed (tetramers or hexasomes), but for simplicity we chose to compare the input nucleosomes with the final naked DNA product. To separate the RSC-dependent released DNA from the non-remodeled nucleosomes, the reactions were subjected to native agarose gel electrophoresis, and DNA of the four bands isolated by gel-extraction. The upper bands, harboring nucleosomes, were named NUC (no RSC) and NUCR (with RSC), whereas the lower, ‘naked’ DNA bands were named DNA (no RSC) and DNAR (with RSC).
Project description:The metabolic response of maize source leaves to low nitrogen supply was analyzed in maize seedlings by parallel measurements of transcriptome and metabolome profiling. Inbred lines A188 and B73 were cultivated under controlled growth chamber conditions and supplied with either sufficient (15mM) or limiting (0.15mM) nitrate supply. Leaf lamina material was harvested at day 20 and day 30 after germination with the fifth and sixth leaf representing the main source leaf respectively. Four replicates were collecetd from individual plants for each combination of genotype, growth stage and nitrogen treatment. The leaf material was frozen, homogenised and aliquoted for transcriptome and metabolome analysis. The molecular data was further supplemented by phenotypic characterisation of the maize seedlings under investigation. Limited availability of nitrogen caused strong shifts in the metabolite profile of leaves. The transcriptome was less affected by the nitrogen stress but showed strong genotype and age dependent patterns. Nitrogen starvation initiated the selective down-regulation of processes involved in nitrate reduction and amino acid assimilation; ammonium assimilation related transcripts on the other hand were not influenced. Carbon assimilation related transcripts were characterized by high transcriptional coordination and general down-regulation under low nitrogen conditions. Nitrogen deprivation caused a slight accumulation of starch, but also directed increased amounts of carbohydrates into the cell wall and secondary metabolites. The decrease in N availability also resulted in accumulation of phosphate and by strong down-regulation of genes usually involved in phosphate starvation response, underlining the great importance of phosphate homeostasis control under stress conditions. Maize inbred lines A188 and B73 were cultivated in pots containing nutrient poor peat soil under the controlled conditions of a growth chamber. The plants were fertilized with modified Hoagland solutions containing either 15mM (high N) or 0.15mM nitrate (low N). Source leaf lamina were harvested at day 20 and day 30 after start of germination for parallel analysis of transcriptome and metabolome profiles. The molecular data is further supplemented by phenotypic characterization of the maize seedlings under investigation.