Foxh1 is a locus-specific PRC2 recruiter governing germ layer silencing

Area of Science:

• Developmental Biology
• Epigenetics
• Molecular Biology

Background:

• Polycomb Repressive Complex 2 (PRC2) is crucial for gene regulation during embryogenesis, but its recruitment mechanisms are debated.
• A prevailing model suggests PRC2 binds chromatin intrinsically, independent of transcription factors.

Purpose of the Study:

• To investigate the role of the pioneer transcription factor Foxh1 in recruiting PRC2 to specific genomic loci during early Xenopus development.
• To elucidate the dual function of Foxh1 in gene activation and repression.

Main Methods:

• Utilized maternal Foxh1-null Xenopus embryos.
• Analyzed the recruitment of Ezh2 (PRC2 catalytic subunit) to Foxh1-bound loci.
• Assessed global H3K27me3 levels.

Main Results:

• Foxh1 directly recruits Ezh2 to its bound genomic sites.
• Loss of Foxh1 leads to impaired Ezh2 recruitment and a global decrease in H3K27me3.
• Foxh1 exhibits dual function: activating endodermal genes in endoderm and recruiting PRC2 to silence them in ectoderm.

Conclusions:

• Foxh1 acts as a critical factor in directing PRC2 localization during zygotic genome activation.
• This recruitment by Foxh1 is essential for establishing spatially coordinated epigenetic states during early embryogenesis.
• Supports a dual-function model for Foxh1 in both gene activation and repression.