Cell-specific occupancy dynamics between the pioneer-like factor Opa/ZIC and Ocelliless/OTX regulate early head...

Area of Science:

• Developmental biology
• Genetics
• Molecular biology

Background:

• Embryonic development involves pluripotent cells differentiating into tissues, guided by transcription factors.
• Key conserved factors include Zelda, Odd-paired (Opa)/ZIC3, and Ocelliless (Oc)/OTX2.
• Opa is crucial for early zygotic gene activation, but its role in head specification is unclear.

Purpose of the Study:

• To investigate the roles of Opa and Oc in Drosophila embryonic head cell fate determination.
• To determine if Opa and Oc interact with distinct cis-regulatory regions.
• To elucidate the dynamic expression and regulatory interactions of Opa and Oc.

Main Methods:

• Super-resolution microscopy
• Meta-analysis of single-cell RNA sequencing (scRNA-seq) datasets
• Analysis of single-embryo RNA-seq data
• Chromatin immunoprecipitation sequencing (ChIP-seq) for Oc
• In situ hybridization

Main Results:

• Opa and Oc exhibit overlapping, dynamic expression domains in the embryonic head region.
• Both factors are co-transcribed at the blastula stage.
• A subset of Opa-bound genes are regulated independently of Opa in the cellularized embryo.
• Oc binds to late, head-specific enhancers and activates them independently during gastrulation.

Conclusions:

• Opa and Oc have distinct regulatory roles in embryonic head development.
• Opa competes with Oc for regulating certain genes during gastrulation.
• Oc plays a crucial role in head-specific zygotic transcription at later developmental stages.