Fig. 7: Med23 deletion leads to the loss of the Sp1-dependent P300-binding signal.

a Venn diagram showing the genome-wide overlap between Sp1- and p300-bound gene sites in WT iOLs. b Pie chart presenting the genomic distribution of the co-occupied regions of Sp1 and P300 in WT iOLs. c The Sp1-binding density at the sites co-occupied by Sp1 and P300 (left) and the enrichment of P300 (middle) and H3K27Ac (right) centered around Sp1-binding sites in Med23^+/+ iOLs and Med23^–/– iOLs. d–f Averaged ChIP-seq signals of Sp1 (d), P300 (e), and H3K27Ac (f) centered at active enhancer regions in Med23^+/+ iOLs (green) and Med23^–/– iOLs (red). g, h “Hockey-stick” plots showing putative enhancers and SEs determined by H3K27Ac ChIP-seq in Med23^+/+ iOLs (g) and Med23^–/– iOLs (h). The horizontal line represents the demarcation between typical enhancers (below) and SEs (above). i, j Interactive Genomics Viewer (IGV) browser views showing ChIP-seq for Sp1, P300, H3K27Ac at the representative loci. ChIP-seq was performed in Med23^+/+ iOLs and Med23^–/– iOLs. The ChIP-seq signal was normalized to CPM (Counts Per Million mapped reads). k Western blot analysis of total Sp1 and other indicated factors bound to the DNA template in an immobilization assay with WT and Med23-KO HeLa cells. l In vitro transcribed RNA products from the GC template during the transcription step were analyzed by reverse transcription followed by qPCR quantification. m Northern blot of total RNA from transcription step of immobilized template assay. Probes are specific for the transcripts of DNA template. n A schematic model showing that controls OL lineage progression by facilitating Sp1-dependent P300 recruitment to enhance H3K27Ac deposition in lineage regulatory genes for promoting OPC differentiation. OLX is indicated as a potential lineage-specific factor that has not been identified in our study.