Six1 Regulates Mouse Incisor Development by Promoting Dlx1/2/5 Expression

Area of Science:

• Developmental Biology
• Genetics
• Oral Biology

Background:

• Tooth development relies on complex gene regulatory networks involving epithelium and ectomesenchyme.
• The transcription factor SIX1 is implicated in lower incisor development, but its precise role and mechanisms are unclear.

Purpose of the Study:

• To elucidate the regulatory role of SIX1 in dental mesenchyme development during incisor formation.
• To understand the molecular mechanisms by which SIX1 controls cell fate transitions in tooth development.

Main Methods:

• Utilized Six1 deletion mouse models to study incisor development.
• Performed single-cell RNA sequencing to create a transcriptome atlas of tooth germ development (bud to bell stage).

Main Results:

• Identified key transcription factors, including Dlx1/2/5, promoting dental papilla formation from dental ectomesenchyme.
• Demonstrated that SIX1 deletion impairs the transition from dental ectomesenchyme to dental papilla.
• Showed SIX1 directly binds to Dlx1/2/5 promoters, driving their co-expression and subsequent epigenetic/transcriptional changes.

Conclusions:

• SIX1 is indispensable for lower incisor development.
• SIX1 regulates dental mesenchyme cell fate transitions through the Dlx1/2/5 regulatory network.
• Findings provide insights into transcription factor-driven networks governing tooth development.