Cells were fixed with 2mM disuccinimidyl glutarate (DSG) for 45 mins and 1% formaldehyde for 10mins, and followed by glycine for 5 mins. Chromatin DNA was sheared to 200–500 bp average in size by sonication and chromatin was immunoprecipitated with antibodies. Protein A/G beads Sigma were added and incubated overnight at 4°C. After washing and elution, the protein–DNA complex was reverse-crosslinked by heating at 65°C, and immunoprecipitated DNA was purified by using QIAquick Spin column. ChIP-seq libraries were prepared using the KAPA Library Preparation Kit (KK8201)