Arl4c is involved in tooth germ development through osteoblastic/ameloblastic differentiation.

Area of Science:

• Developmental Biology
• Cell Biology
• Molecular Biology

Background:

• Tooth germ development involves complex epithelial-mesenchymal interactions and signaling pathways.
• ADP-ribosylation factor (Arf)-like 4c (Arl4c) is known to induce cell proliferation and is implicated in epithelial morphogenesis and tumorigenesis.
• The specific role of Arl4c in tooth germ development, beyond its proliferative effects, remained largely uncharacterized.

Purpose of the Study:

• To investigate the role of Arl4c in murine tooth germ development.
• To elucidate the cellular and molecular mechanisms by which Arl4c influences tooth formation.

Main Methods:

• Single-cell RNA sequencing (scRNA-seq) to identify Arl4c expression patterns in developing mouse teeth.
• In vitro culture of mouse tooth germ rudiments with ARNO/Arf6 pathway inhibitors.
• Loss-of-function studies using siRNA and shRNA to deplete Arl4c expression.
• RNA-seq, Gene Set Enrichment Analysis (GSEA), and Gene Ontology (GO) analysis to identify affected molecular pathways.

Main Results:

• Arl4c expression was specifically detected in various odontogenic epithelial cell layers of postnatal mouse molars and incisors.
• Inhibition of the ARNO/Arf6 pathway impaired tooth germ morphology, including size, width, and cusp height.
• Arl4c depletion reduced cell proliferation and osteoblastic cytodifferentiation in odontogenic epithelial cells.
• RNA-seq and GSEA/GO analyses revealed downregulation of osteoblastic differentiation-related genes and pathways upon Arl4c knockdown.

Conclusions:

• The Arl4c-ARNO/Arf6 pathway is essential for normal tooth germ development.
• Arl4c plays a critical role in regulating cell proliferation and osteoblastic/ameloblastic differentiation during tooth formation.
• These findings highlight Arl4c as a key regulator in the intricate process of tooth development.