Fig. 1.

Model illustrating the role of CBX proteins in PRC1 regulation in pluripotent cells and during differentiation. (A) In pluripotent cells, the CBX7/PRC1 complex binds to the regulatory regions of the genes involved in development and differentiation and the genes encoding the CBX2, 4, and 8 proteins, which represses their transcription. This binding depends on H3K27me3 established by PRC2. (B) Expression of microRNAs miR-125 and miR-181 , which repress CBX7 expression, is activated during differentiation. The absence of CBX7/PRC1 results in activation of the differentiation genes, as well as Cbx2 , 4 and 8 . PRC1, together with CBX2, CBX4, and CBX8, represses the transcription of the genes responsible for pluripotency maintenance and Cbx7 [55]