PPARG Epigenetic Deregulation and Its Role in Colorectal Tumorigenesis

Figure 3

Schematic drawing of the proposed mechanism(s) involved in PPARG silencing. (a) In PPARγ-expressing cells, the unmethylated or partially methylated core promoter is bound by still unknown transcriptional factors, among which only the zinc-finger protein ZAC has been identified. Active histone marks, such as H3K9ac, H3K4me3 and H4K16ac are present together with the RNA polimerase II. (b) Upon unknown stimuli, the PPARG promoter becomes hypermethylated, enriched in H3K9me2, H3K9me3 and H3K27me3. Furthermore, a repressive complex containing UHRF1, MeCP2, DNMT3b, HDAC1, SUV39H1 and EZH2 is recruited inducing transcription repression. Partially adapted from reference [39].