Fig. 7

Summary of PRC2 functions during oocyte growth and maturation and pre-implantation development. All three essential components of PRC2 are present in growing oocytes only at the primary to secondary stages and establish H3K27me3 on H3K27me3-imprinted genes and a wide range of developmental genes, potentially programming Eed oocyte DEG expression in offspring. As this activity immediately precedes de novo DNA methylation, we propose that H3K27me3 established prior to DNA methylation may act as a “place-keeper” protecting developmental genes from modifications such as H3K36me3 and/or DNA methylation. Cytoplasmic PRC2 proteins and/or mRNA are inherited via the mature oocyte and regulate pre-implantation development, including X-inactivation, H3K27me3-dependent imprinting [31, 34, 35] and establishment of maternal–paternal equivalence at non-imprinted sequences. Loss of PRC2 in the oocyte leads to embryo growth restriction [33] but offspring are ultimately overgrown immediately after birth [40]