For RNA-Seq: the total RNAs were purified using Qiagen's miRNeasy micro kit (Qiagen cat# 217084) plus Qiagen's DNase set (Qiagen cat# 79254) for on-column DNase digestion option. PolyA-tailed RNAs were purified from pure total RNA using Dynabeads® mRNA DIRECT™ Kit (ambion life technologies cat# 61012). ChIP and Hi-C follow the protocols described previously in (PMID: 17512414) and (PMID: 25497547 ) with minor modifications. Library constructions for ChIP-Seq, RNA-Seq and Hi-C follow the protocols described previously in (PMID: 17512414), (PMID: 19528076) and (PMID: 25497547 ) with minor modifications.