Total RNA was extracted with RNeasy Mini kit (QIAGEN). For ChIP-seq, chromatin was sonicated with Covaris S2. ATAC-seq was carried out with a standard protocol. 150 ng of total RNA from each sample was used for library preparation. mRNA was purified with NEBnext poly(A) mRNA magnetic isolation module (NEB), and sequence libraries were prepared with NEBnext Ultra II Directional RNA library prep kit (NEB) following the manufacturer's protocol. ChIPmentation was carried out for H3K4me3 ChIP-seq library construction with 7 min incubation with a Tn5 tagmentation enzyme solution (Schmidl et al., 2015). ATAC-seq was carried out as described previously (Buenrostro et al., 2013).