Identification and Characterization of ATOH7-Regulated Target Genes and Pathways in Human Neuroretinal Development

Area of Science:

• Developmental Biology
• Genetics
• Ophthalmology

Background:

• The transcription factor atonal basic helix-loop-helix transcription factor 7 (ATOH7) is vital for developing retinal ganglion cells (RGCs).
• Mutations in ATOH7 are linked to optic nerve hypoplasia (ONH) and persistent hyperplasia of the primary vitreous (PHPVAR) in humans.

Purpose of the Study:

• To elucidate the role of ATOH7 in human neuroretinal development using induced pluripotent stem cells (hiPSCs).
• To identify ATOH7-regulated genes involved in RGC development and associated disorders.

Main Methods:

• Generated ATOH7 knockout and reporter hiPSCs differentiated into retinal organoids.
• Employed CUT&RUN-seq, RNA-seq, and single-cell RNA sequencing (scRNA-seq) to analyze gene expression and targets.
• Assessed organoid development for axon sprouting, RGC numbers, and cell type distribution.

Main Results:

• Mutant organoids showed impaired axon sprouting, reduced RGCs, and altered cell type composition.
• Identified 469 differentially expressed genes, enriched for axon development/guidance and Notch signaling pathways.
• ATOH7 was found to induce RGC-specific genes and inhibit alternative cell fates.

Conclusions:

• Human ATOH7 is crucial for directing progenitor cell fate towards RGCs during retinal development.
• Identified candidate genes contributing to ATOH7-associated optic nerve and retinovascular anomalies.
• Findings offer insights into potential therapeutic targets for ONH and PHPVAR.