All-Trans Retinoic Acid Impacts Early Palatal Shelves Development via the Wnt and TGF-β Signaling Pathways

<b>Background/Objectives:</b> All-trans retinoic acid (atRA), a potent derivative of vitamin A, is recognized as a significant teratogen for inducing cleft palate in both humans and mice. The molecular mechanisms underlying it remain intricate and incompletely elucidated. The advent of single-cell sequencing technology offers novel methodologies to investigate the mechanisms by which atRA induces cleft palate. <b>Methods:</b> In this study, we use C57BL/6 mice to conduct cleft palate models, comprising a control group and an atRA-exposed group. Palatal shelves were collected at embryonic day 12.5 (E12.5) for 10x single-cell sequencing analysis to discern and compare the cellular and molecular disparities between the two groups. Validation of the findings was performed using Quantitative real-time polymerase chain reaction and Western blot techniques. <b>Results:</b> The findings indicate that at E12.5, atRA predominantly affects the mesenchymal and epithelial cells of the palatal shelves, inhibiting cellular proliferation and migration. The primary mechanism of atRA's effect involves modulation of the Wnt and TGF-β signaling pathways. Furthermore, the Ppp1r14b gene was identified as a critical mediator in atRA's interaction with these pathways. <b>Conclusions:</b> This study provides a more comprehensive understanding of the mechanisms underlying atRA-induced cleft palate formation. It highlights the significance of the Wnt and TGF-β pathways, as well as the Ppp1r14b gene during this procedure.