library_construction_protocol: Dissected CLH or CLT tissues were homogenized and cross-linked with 1% paraformaldehyde for 8 min (H3K27ac) or for 15 min (MED1), sonicated using a ultrasonicator (Covaris) to obtain DNA fragments with an average length of 300±50 bp. Sheared chromatin was thereafter immunoprecipitated with Protein A-coated magnetic beads (Diagenode) preincubated with 4.5 microgram/IP MED1 antibody (Bethyl A300-793A) or 3 ug/IP H3K27ac antibody (ab4729, Abcam). Chromatin input samples were used as reference. Complexes were then washed and eluted from the beads with washing buffer and crosslinks were reversed by incubation at 65°C for 4 hours. Immunoprecipitated DNA along with genomic DNA (Inputs) were purified using the IPure v2 kit (Diagenode). IP efficiency was confirmed by qPCR using primers provided in the kits. Experiments were carried out in duplicates. ChIP-Seq libraries were generated using the Accel-NGS 2S Plus DNA library kits (Swift Sciences) and amplified by PCR for 11-13 cycles. High molecular weight smear was removed in the library by right side size selection using SPRI beads (Beckman Coulter). The libraries were quantified by Agilent 2100 Bioanalyzer with the high sensitivity DNA assay and sequenced on an Illumina HiSeq 4000 (UCSF Center of advanced technology) in a single strand 50 bp run.