The cardiomyocytes were isolated from the adult mice heart according to previous protocol, and the cardiomyocytes were fixed and then lysed. Lysates were clarified from sonicated nuclei and histone-DNA complexes were isolated with antibody. Libraries were prepared according to Illumina's instructions accompanying the ChIP library preparation Kit (NEBE7370). Briefly, DNA was end-repaired. The blunt, phosphorylated ends were treated with TA ligase Master mix and NEBNext Adaptor for Illumina. After adaptor ligation, DNA was PCR amplified with Illumina primers for 15 cycles. The DNA library was purified and the size of DNA fragments was selected by AMPure XP beads. The libraries were then sent to be sequenced.