Fig. 6

Model for the balance between H2A.Z and H3.3 in regulating H3K27me3 deposition by PRC2 in mES cells. In this model, H2A.Z promotes PRC2 activity by facilitating chromatin compaction, while H3.3 counteracts the positive action of H2A.Z on H3K27me3 deposition by PRC2. Therefore, H3.3 and H2A.Z function coordinately in fine-tuning PRC2 enzymatic activity to control H3K27me3 level through modulating the chromatin structure/compaction. Here we use “Bagua” (also named “the Eight Diagrams”—eight combinations of three whole or broken lines formerly used in divination), which has been used in Taoist cosmology, to iconically summarize the molecular mechanism by which H2A.Z and H3.3 coordinately regulate PRC2 activity and H3K27me3. In our model, each trigram of the four, which originally represents the fundamental principle of reality in Taoist cosmology, represents a range of four interrelated chromatin status as shown in our experiments. In addition, each line either “broken” (highlighted by black bars) or “unbroken” (highlighted by red bars) respectively represents yin or yang, a theory describe how seemingly opposite or contrary forces may actually be complementary, which may perfectly represent the regulatory effects of H2A.Z and H3.3 on chromatin structure and PRC2 activity/H3K27me3 in our study