Feed-forward loops by NR5A2 ensure robust gene activation during pre-implantation development

Area of Science:

• Developmental Biology
• Epigenetics
• Genomics

Background:

• Pioneer transcription factors are essential for early embryonic development.
• The collective function of pioneer factors in regulating zygotic genome activation and cell differentiation is not well understood.

Purpose of the Study:

• To investigate the chromatin-binding profiles of the pioneer factor NR5A2 during mouse pre-implantation development.
• To identify co-regulators of NR5A2 and elucidate their collective regulatory mechanisms.

Main Methods:

• Chromatin immunoprecipitation sequencing (ChIP-seq) to determine NR5A2 binding.
• Analysis of KLF and GATA family transcription factors as co-regulators.
• In vitro nucleosome binding assays.

Main Results:

• NR5A2 chromatin-binding profiles were mapped during the totipotency-to-pluripotency transition.
• KLF5 and GATA6 were identified as key co-regulators of NR5A2.
• NR5A2 regulates Klf5 and Gata6 expression, which in turn co-regulate NR5A2.
• KLF5 facilitates H3K27ac deposition at co-occupied genomic regions.
• NR5A2, KLF5, and GATA6 were shown to bind nucleosomes simultaneously.

Conclusions:

• A feed-forward regulatory mechanism involving NR5A2, KLF5, and GATA6 ensures robust gene activation during early development.
• These pioneer factors collectively bind to nucleosomes to promote zygotic genome activation and cell differentiation.