TFAP2 paralogs regulate midfacial development in part through a conserved ALX genetic pathway.

Area of Science:

• Developmental Biology
• Genetics
• Craniofacial Development

Background:

• Cranial neural crest development relies on gene regulatory networks (GRNs).
• Midfacial shape variation arises from GRN fine-tuning, but network activation is unclear.

Purpose of the Study:

• To investigate the role of TFAP2 paralogs in midfacial neural crest development.
• To identify downstream targets and regulatory mechanisms of TFAP2 in the midface.

Main Methods:

• Murine neural crest-specific inactivation of Tfap2a and Tfap2b.
• Bulk and single-cell RNA sequencing (RNA-seq) for gene expression profiling.
• Chromatin immunoprecipitation sequencing (ChIP-seq) to identify direct TFAP2 targets.
• Zebrafish tfap2a mutants for cross-species validation.

Main Results:

• Concerted inactivation of Tfap2a and Tfap2b caused midfacial clefts and skeletal abnormalities.
• Loss of TFAP2 paralogs dysregulated midface GRN components, including reduced ALX gene expression.
• ChIP-seq indicated direct positive regulation of ALX genes by TFAP2 family members.
• Conservation of the TFAP2-ALX regulatory axis was observed in both mouse and zebrafish.

Conclusions:

• TFAP2 paralogs are crucial regulators of vertebrate midfacial development.
• TFAP2 proteins activate ALX transcription factor gene expression, contributing to midface morphogenesis.
• This regulatory axis is conserved across vertebrates, underscoring its fundamental importance.