library_construction_protocol: Cell pellet of ~1x10^7 cells was resuspended in 1 mL nuclei extraction buffer (10 Mm Hepes, PH 7.5; 300 mM NaCl; 3 mM MgCl2; 0.5% IGEPAL CA-630; 0.1% SDS) with EDTA-free protease inhibitor cocktail (Roch, 05892791001) and incubate on ice for min. Then cell pellet was washed once with buffer A (10 mM Tris, PH 7.5; 10 KCl; 60 mM NaCl; 3 mM MgCl2) with EDTA-free protease inhibitor cocktail. Chromatin was crosslink reversed by heating at 65 °C for 6 hours, and DNA were extracted using a standard phenol-chloroform extraction procedure. For paired-end sequencing, libraries without size selection were prepared using NEBNext Ultra DNA Library Prep Kit for Illumina (E7370L). Illumina libraries were sequenced on a DNBSEQ-T7 (MGI) platform with PE150 model.