title: GSM6288696: RL3024_ChIPseq_Dox_H3K27me3; Homo sapiens; ChIP-Seq
library_construction_protocol: Cells were washed two times with 10 ml of PBS and crosslinked for 5 minutes in 50 mM HEPES-KOH, pH 7.5, 100 mM NaCl, 1mM EDTA, 1% formaldehyde. The crosslinking reaction was quenched by the addition of glycine to a final concentration of 125 mM and washed twice with phosphate buffered saline (PBS). All subsequent solutions were supplemented with a protease inhibitor cocktail (Sigma Cat. # P8340). Cells were scraped off the plates with a rubber policeman in 10 ml of PBS and centrifuged at 3,000 rpm for 5 minutes in a swinging bucket rotor. The cell pellets were resuspended in 10 ml of 50 mM HEPES-KOH, pH 7.9, 140 mM NaCl, 1 mM EDTA, 10% glycerol, 0.5% NP-40, 0.25% Triton X-100, incubated on ice for 10 minutes and centrifuged at 3,000 rpm for 10 minutes in a swinging bucket rotor. Cell pellets were washed twice by gently adding 10 mM Tris-HCl, pH 8.1, 200 mM NaCl, 1 mM EDTA to the cell pellets, trying not to disturb the pellets, and centrifuged at 3,000 rpm for 5 min. Finally the cell pellets were resuspended in 0.1% SDS, 1 mM EDTA and transferred to a Covaris TC12x12 tube. The chromatin was sheared using a Covaris S2 sonicator with the following settings: time 12 min, duty cycle 5%, intensity 4, cycles per burst 200, temperature 4˚C, power mode frequency sweeping. Triton X-100 and NaCl were added to a final concentration of 1% and 150 mM respectively. The sheared chromatin was centrifuged at maximum speed in a microfuge for 15 minutes at 4˚C and the supernatant was transferred to a new tube. Genomic DNA was fragmented with a Covaris S2 sonicator to a mean length of 200 bp, then end-repaired, A-tailed, ligated to methylated Illumina TruSeq adapters, bisulfite converted and subjected to 7 cycles of PCR amplification with KAPA HiFi Uracil+ DNA polymerase (KAPA Biosystems).