Unbiased CRISPR Screen Identified H3K9 methylation as deterministic epigenetic barriers for Primordial Germ Cell Specification

Authors

• XK Wang
• H Zhou
• S Long
• A Shaukat
• SR Malki
• PY Yang
• M Zhang
• G Hu

Abstract

Specification of primordial germ cells (PGCs) lineage ensures the transmission of genetic and epigenetic information to the next generation. The induction of germ cell-specific genes, repression of the somatic program, and widespread epigenetic remodeling are known to accompany this process. However, the underlying mechanism that governs PGC specification is not fully understood.
We conducted an unbiased CRISPR screen during ESC differentiation toward the PGC lineage and identified several epigenetic regulators, especially H3K9 methyltransferases (HMTs) play critical roles in PGC differentiation. Depletion of H3K9 HMTs enhances PGC derivation from ESCs drastically. Consistently, H3K9 HMT inhibition using small molecules also significantly promotes PGC specification. Transcriptome analysis indicated that H3K9 HMT deletions result in the de-repression of key germ cell genes at early stages during differentiation, suggesting that H3K9 methylation likely serves as a major epigenetic barrier against the PGC fate. We are currently using additional genomic approaches including H3K9me3 ChIP-seq and ATAC-seq to dissect the molecular underpinning. In addition, we are carrying out a time-series single-cell analysis, aiming to define the critical developmental branch point(s) at which H3K9 HMT deletions divert cells toward the germ cell fate. Finally, we have generated H3K9 HMT knockout mouse models and will test whether the deletion can promote PGC specification in vivo as well.
Together, our study uncovered that H3K9 methylation plays a deterministic role in PGC cell fate determination. We envision the highly efficient PGC derivation will provide new opportunities to model germ cell development in vitro and develop potential therapeutic applications.

Scientific Focus Area: Stem Cell Biology

This page was last updated on Tuesday, August 6, 2024