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. 2020 Jul 8;9(7):1639. doi: 10.3390/cells9071639

Figure 1.

Figure 1

PRC2 and its function in transcriptional regulation. The PRC2 facilitates gene silencing through methylation of H3 lysine 27 and is composed of the core components Enhancer of Zeste Homolog 2 (EZH2), Embryonic Ectoderm Development (EED), Suppressor of Zeste 12 (SUZ12) and Retinoblastoma-binding Protein (RBBP7/4). Other non-essential regulatory proteins, thought to have modulatory and enhancing effects on PRC2 function, include Adipocyte Enhancer-binding Protein 2 (AEBP2), Polycomb-like Proteins (PCLs) and Jumonji and AT-rich Interaction Domain Containing 2 (JARID2) [4,6]. The polycomb complex PRC1, ubiquitinates H2A lysine 119 (H2AK119) and can act downstream of PRC2 to induce gene repression, by binding of trimethylated H3 lysine 27 (H3K27me3) via its Chromobox (CBX) component. Other components include Polycomb Group RING Finger Protein 4 (BMI1), Ring Finger Protein 1 (RING1) and Polyhomeotic Homolog 1 (PHC1) [5]. EZH2 physically interacts with Additional Sex Combs Like 1 (ASXL1) for PRC2 recruitment to target genes [10] and DNA Methyltransferases (DNMTs) to regulate DNA methylation [11]. Demethylation of H3K27 is facilitated through Lysine Demethylase 6A (KDM6A/UTX) and Lysine Demethylase 6B (KDM6B/JMJD3) [12]. me: methylation; ub: ubiquitination; ON/OFF: transcriptional activation/repression of target genes such as Homeobox (HOX) genes.