GSM7386090: MCF-7_DMSO  control_H3K9me2; Homo sapiens; ChIP-Seq
Crosslinked chromatin was prepared by adding 1% formaldehyde to the culture for 5 min followed by the addition of glycine to 0.125 M final concentration for 5 minutes to stop the cross-linking. Chromatin was sheared by sonication in a Bioruptor UCD-200 (Diagenode) for 10 min at 30 s intervals, power setting high, to a size of 300–800 bp. ChIP was performed by adding 1.8 µg of H3K9me2 antibody to ChIP buffer (100 mM NaCl, 20 mM Tris pH-7.5, 6 mM EDTA, 1% Triton X- 100). The DMSO control and 27-HC treated samples  were added to the mixture and incubated at 4 °C for overnight, followed by the addition of 15 μl protein A Dynabeads and further incubated for 4 h. After washing with buffers containing 180 mM NaCl, immuno-precipitated DNA was eluted and purified using PCR purification columns. Libraries for ChIP sequencing were prepared using NEB Next Ultra II DNA Library preparation kit. In brief, ChIP DNA and the Input DNA are subjected to various enzymatic steps for repair the ends and tailing with dA-tail followed by ligation of adapter sequences. These adapter ligated fragments are then size selected using SPRI beads. Next, the size selected fragments are indexed during limited cycle PCR to generate final libraries for paired-end sequencing. The resulting libraries are quantified before getting sequenced on Illumina HiSeq 2500/4000 system to generate 2X50 bp sequence reads.