Cells were crosslinked with 1% formaldehyde for 10 min at room temperature. The reaction was quenched by 0.125 M glycine for 5 min. Fixed cells were lysated with ChIP lysis buffer 1 (50 mM HEPES-KOH, pH7.5, 140 mM NaCl, 1 mM EDTA, pH8.0, 1% Triton X-100, 0.1% DOC) on ice and lysis buffer 2 (10 mM Tris pH8.0, 200 mM NaCl, 1 mM EDTA, 0.5 mM EGTA) at room temperature. Chromatin was digested with MNase (Cell Signaling) in digestion buffer (10 mM Tris 8.0, 1 mM CaCl2, 0.2% Triton X-100) at 37°C for 15 min. The nucleus was broken down by one pulse of bioruptor with high output. Chromatin were incubated overnight at 4°C and protein A+G Dynabeads were added to the reaction for another 1.5 hour. Magnetic beads were washed and chromatin was eluted. Eluted DNA was treated with proteinase K at 55°C for 45 min and decrosslinked at 65°C overnight. Zymo ChIP DNA clean and concentrator kit (zymo, cat. no. D5205) was used to purify the ChIP DNA 10 ng ChIP DNA was used for library construction. NEBNext Ultra DNA Library Prep Kit (NEB, E7645) was used to prepare sequencing library