Profiles of Wnt pathway gene expression during tooth morphogenesis.

Area of Science:

• Developmental Biology
• Molecular Biology
• Genetics

Background:

• The Wnt signaling pathway is critical for tooth development (odontogenesis).
• Previous studies identified Wnt pathway components but lacked spatial resolution for comprehensive analysis.
• Understanding synchronized expression of Wnt ligands and modulators is essential for elucidating tooth morphogenesis.

Purpose of the Study:

• To profile the synchronized expression patterns of Wnt10a, Dkk1, and Sost during tooth development.
• To provide cell type-specific insights into Wnt ligand and mediator roles in epithelial-mesenchymal interactions.
• To analyze Wnt pathway-mediated cell communication using single-cell RNA-sequencing.

Main Methods:

• Fluorescent multiplex in situ hybridization for transcript profiling.
• Single-cell RNA-sequencing (scRNA-seq) for gene expression analysis.
• CellChat analysis to examine ligand-receptor interactions in Wnt signaling.

Main Results:

• Wnt10a initially localized to the epithelium, while Sost and Dkk1 were in the mesenchyme during early tooth bud stages.
• Wnt10a expression shifted to the mesenchyme by E15.5, with Sost and Dkk1 remaining in the mesenchyme.
• Co-localization of Wnt10a, Dkk1, and Sost was observed in differentiating odontoblasts and ameloblasts, with novel Wnt10a expression in ameloblasts at cusp tips.
• Wnt modulators showed reduced signals post-mineralization, except in incisor cervical loops.

Conclusions:

• Dynamic spatiotemporal expression of Wnt10a, Dkk1, and Sost is crucial for odontogenesis.
• Co-localization in odontoblasts suggests critical ligand-modulator interactions during cytodifferentiation.
• These findings offer cell-specific insights into Wnt signaling during tooth development and epithelial-mesenchymal crosstalk.