Repression of the soma-specific transcriptome by Polycomb-repressive complex 2 promotes male germ cell development

Area of Science:

• Epigenetics
• Developmental Biology
• Reproductive Biology

Background:

• Polycomb-repressive complex 2 (PRC2) is a key epigenetic regulator involved in stem cell pluripotency and somatic differentiation.
• The role of PRC2 in mammalian male germ cell development, particularly spermatogenesis, remains largely uncharacterized.

Purpose of the Study:

• To investigate the function of PRC2 in male germ cell development.
• To determine the necessity of PRC2 for spermatogonial stem cell (SSC) maintenance and meiotic progression.

Main Methods:

• Conditional mutagenesis was employed to delete core PRC2 subunits (EED and SUZ12) specifically in male germ cells.
• Analysis included assessing SSC populations, monitoring meiotic progression, and examining chromosome dynamics and gene expression.

Main Results:

• PRC2 is required in both mitotic and meiotic germ cells during spermatogenesis.
• Loss of PRC2 led to a scarcity of mutant spermatogonial stem cells, independent of Ink4a/Ink4b/Arf repression.
• Mutant spermatocytes displayed ectopic expression of somatic lamins, abnormal SUN1 protein distribution, and defects in homologous chromosome pairing and synapsis.
• Histone H3 Lys27 trimethylation (H3K27me3) was acquired on stage-specific genes during meiosis, highlighting PRC2's role in the meiotic transcriptional program.

Conclusions:

• PRC2 plays a critical role in maintaining homeostasis and facilitating differentiation during mammalian spermatogenesis.
• Transcriptional repression of soma-specific genes by PRC2 is essential for proper male germ cell development.