DUX4 is a multifunctional factor priming human embryonic genome activation

Area of Science:

• Developmental Biology
• Epigenetics
• Genomics

Background:

• Double homeobox 4 (DUX4) is expressed during early human embryonic development.
• The role of DUX4 in regulating the non-coding genome during pre-implantation stages is not fully understood.

Purpose of the Study:

• To investigate the function of DUX4 in regulating chromatin accessibility and gene expression in human embryos.
• To explore DUX4's role in embryonic genome activation (EGA) and its interaction with the Mediator complex.

Main Methods:

• CRISPR activation to induce DUX4 expression and study its effects on chromatin accessibility.
• Analysis of transcribed enhancer-like regions and their association with repeat elements (ERVL-MaLR).
• DUX4 knockdown experiments in human zygotes to assess its impact on the EGA transcriptome.
• Protein interaction studies to identify DUX4's binding partners, specifically the Mediator complex.

Main Results:

• Induced DUX4 expression altered chromatin accessibility and activated thousands of novel transcribed enhancer-like regions, primarily within ERVL-MaLR repeats.
• CRISPR activation of DUX4-motif enhancers increased expression of key EGA genes, ZSCAN4 and KHDC1P1.
• DUX4 is enriched in human zygotes, with nuclear localization preceding and coinciding with minor EGA.
• DUX4 knockdown altered the EGA transcriptome but did not halt embryonic development.
• DUX4 interacts with the Mediator complex via its C-terminal KIX binding motif.

Conclusions:

• DUX4 acts as a crucial regulator of the non-coding genome during early human embryonic development.
• DUX4 influences chromatin accessibility and activates specific enhancers, impacting embryonic genome activation.
• DUX4's interaction with the Mediator complex is vital for its regulatory functions.