Antigen

Antigen Class

Histone

Antigen

H3K27ac

Cell type

Cell type Class

Neural

Cell type

Glioblastoma

MeSH Description

A malignant form of astrocytoma histologically characterized by pleomorphism of cells, nuclear atypia, microhemorrhage, and necrosis. They may arise in any region of the central nervous system, with a predilection for the cerebral hemispheres, basal ganglia, and commissural pathways. Clinical presentation most frequently occurs in the fifth or sixth decade of life with focal neurologic signs or seizures.

Sample

source_name

Primary glioblastoma tissue

individual

patient CCF3069

tissue

Primary glioblastoma tissue

chip antibody

H3K27ac (Active Motif, 39133)

Sequenced DNA Library

library_strategy

ChIP-Seq

library_source

GENOMIC

library_selection

ChIP

library_construction_protocol

For histone modification and transcription factor ChIP-Seq, tissue extracts were crosslinked in PBS + 1% fresh formaldehyde for 10 minutes at 37 C, quenched for 5 minutes with 125 mM glycine, washed twice in cold PBS with protease inhibitors (complete PI, Roche), and stored at -80 C. Pellets were thawed and lysed in cold cytoplasmic lysis buffer (20 mM Tris-HCl ph8.0, 85 mM KCl, 0.5% NP 40 + PI). Nuclei were pelleted at 3000g , resuspended in cold SDS lysis buffer (1% SDS, 10mM EDTA, 50mM Tris-HCl, pH 8.1 + PI) for 10 minutes, sonicated to an average fragment size of 200-400 bp on a Branson sonifier, and cleared of debris by centrifugation. Samples were diluted 1:10 in ChIP dilution buffer (0.01% SDS, 0.25% Triton X-100, 1.2mM EDTA, 16.7mM Tris-HCl, pH 8.1, 167mM NaCl +PI), and rotated at 4 C overnight with 2-5 ug of antibody towards H3K27ac (Active Motif, 39133) . Antigen-antibody complexes were collected with protein G Dynabeads (Life technologies) for 4 hours at 4 C, and sequentially washed with RIPA buffer (0.1% Na deoxycholate, 0.1% SDS, 1% Triton x-100, 10mM Tris-HCl pH 8.0, 1mM EDTA, 140 Mm NaCl), RIPA/High salt (0.1% Na deoxycholate, 0.1% SDS, 1% Triton x-100, 10mM Tris-HCl pH 8.0, 1mM EDTA, 360 mM NaCl), LiCl Wash Buffer (250mM LiCl, 0.5% NP40, 0.5% deoxycholate, 1mM EDTA, 10mM Tris-HCl, pH 8.0), and TE Buffer (10mM Tris-HCl pH 8.0, 1mM EDTA). Beads were resuspended in Low SDS ChIP elution buffer (10mM Tris-HCl pH 8.0, 0.5M EDTA, 300mM NaCl, 0.1% SDS, 5mM DTT) and incubated for 6 hours at 65 C to elute DNA and reverse crosslinking. Samples were treated with RNAase for 30 minutes and proteinase K for 2 hours at 37 C. ChIP DNA was then purified from supernatants with AMPure beads (Beckman-Coulter). Input DNA was prepared in parallel by adding unenriched, diluted chromatin directly into the elution / reverse crosslinking step. ChIP DNA was end-repaired (End-It, Epicentre), A-tailed (Klenow fragment 3'-->5' exo-, New England Biolabs), and ligated to barcoded illumina adaptors (Quick T4 DNA ligase, NEB). Each reaction was followed by clean-up with AMPure beads (Beckman-Coulter). Ligation products were amplified by PCR for 14-18 cycles with illumina primers and PFU Ultra II HS PCR mix (Agilent). Library size selection to 300-600 bp was performed by two-step AMPure bead selection or gel purification (E-Gel SizeSelect 2%, Life technologies).

Sequencing Platform

instrument_model

NextSeq 500

hg38

Number of total reads

22081963

Reads aligned (%)

96.0

Duplicates removed (%)

4.2

Number of peaks

27848 (qval < 1E-05)

hg19

Number of total reads

22081963

Reads aligned (%)

95.7

Duplicates removed (%)

4.4

Number of peaks

27767 (qval < 1E-05)