During development, cells of the forming embryo give rise to primordial germ cells (PGCs), which ultimately form oocytes and sperm and pass an individual’s genetic and epigenetic information to the following generation. Epigenetic modifications involve chemical modifications to the chromatin (DNA and associated proteins) that facilitate DNA packaging and mark or “flag” genes for expression and repression in each cell type.
With each generation, the epigenetic information contained in the genome is erased or ‘reprogrammed’ during fetal germ cell development. New epigenetic modifications are established during sperm and oocyte development, and this epigenetic information influences gene expression and cell differentiation in the next generation. However, with the exception of DNA methylation, many of the epigenetic modifications and regulators that control germ cell development and epigenetic programming of the germ-line remain unknown.
Polycomb Repressive Complex 1 (PRC1) and Polycomb Repressive Complex 2 (PRC2) are involved in the epigenetic regulation of developmental genes during embryogenesis. PRC2 is comprised of 3 core components: Enhancer of Zeste 1/2 (EZH1/2); Supressor of Zeste 12 (SUZ12) and Embryonic Ectoderm Development (EED). The PRC2 complex mediates trimethylation of lysine 27 in histone 3 (H3K27me3), an epigenetic modification that is critical for gene silencing.
To date, little is known about the expression profile of PRC2 subunits in the developing germ-line. Here, we use qPCR and immunofluorescence to determine the spacial and temporal profiles of PRC2 components and H3K27me3 during epigenetic reprogramming and development of the germ-line.