For ChIP-seq, chromatin was fixed with 1% formaldehyde solution, fragmented, and precipitated with H3K9me3 antibody. DNA was quantified using the PicoGreen dsDNA Assay Kit. Library preparation for ChIP-seq was completed using ThruPLEX® DNA-Seq (Rubicon Genomics) kit. Libraries were assessed for quality using electrophoresis on an Agilent Bioanalyzer (Agilent) and size-selected for 200~800 bp fragments.