Chromatin immunoprecipitation (ChIP) sequencing: Cells were cross-linked with 1% formaldehyde for 10 minutes, quenched with 0.125 M glycine for 10 minutes; then, the cell pellets were resuspended in low salt Lysis buffer (50 mM HEPES/KOH, PH 7.5, 150 mM NaCl, 1% Trixon-X 100, 0.05% SDS, 10 mM EDTA, and proteinase inhibitors), and sonicated with a Q800R2 DNA shearing sonicator (Qsonica LLC, newtown, CT) for 20 min in 30-s intervals to shear the chromatin into 200- to 400-bp lengths. Chromatin was immunoprecipitated with the indicated antibodies and Protein A/G PLUS-Agarose (Santa Cruz, Santa Cruz, CA, #sc-2003). For, H3K9me2-ChIP ChIP, cells were cross-linked, quenched, and washed as described above. Furthermore, the sonicated chromatin was incubated with anti-H3K9me2 overnight at 4°C Then beads were washed with low salt lysis buffer and low salt buffer (10 mM Tris–HCl pH 8.0, 250 mM LiCl, 1 mM EDTA, 0.5% NP40, 0.5% Na-Deoxycholate), and DNA was eluted in elution buffer (50 mM Tris–HCl pH 8.0, 10 mM EDTA, 1% SDS) with Proteinase K (Yeasen, Shanghai, China, # 10401ES60) and RNase A (Thermo Fisher, Waltham, MA, #EN0531) in 65◦C for 4 h. ChIP DNA libraries and input DNA samples were prepared as directed by the protocol of VAHTS Universal DNA Library Prep Kit for Illumina (Vazyme Biotech, Nanjing, China, #ND617-01) and Cut&Tag DNA libraries. were prepared by using HyperactiveTM In-Situ ChIP Library Prep Kit for Illumina (Vazyme Biotech, Nanjing, China, #TD901-01).