Lysates were clarified from sonicated nuclei and histone-DNA complexes were isolated with antibody. The ChIP DNA library for NEXT Seq500 sequencing was constructed using VAHTS Turbo DNA Library Prep Kit for Illumina(Vazyme Biotech) according to the manufacturer's instruction. Briefly, 10ng ChIP DNA was end repaired and a dA was added. Then the DNA was ligated with adaptors. Adaptor-ligated DNA was purified using AMPure XP beads. The purified DNA was amplified by PCR for 15 cycles, followed by size selection using two round AMPure XP beads and eluted in 25 ul water. The library was quantified with VAHTS Library Quantification Kit for Illumina(Vazyme Biotech). The DNA was diluted to 10 nM before sequencing.