AIM:To investigate the mechanism by which muscle segment homeobox 2(Msx2)regulates the differentiation of outer enamel epithelial cells in the enamel organ.METHODS:Tissue paraffin sections were prepared and subjected to hematoxylin-eosin(HE)staining to analyze the effect of Msx2 deficiency on the differentiation status of epithelial cells in the enamel organ at the morphological level.At the ultrastructural level,alterations in cell structure were analyzed.The intermediate steps mediating cell differentiation were identified.Transcriptome sequencing analysis was performed to validate the molecular mechanisms underlying the observed phenomena.RESULTS:Msx2 deficiency was innovatively found to induce severe squamous epithelial hyperplasia in outer enamel epithelial cells of enamel organ,accompanied by dynamic restructuring of the cell cytoskeleton and alterations in cell adhesion at the ultrastructure level.As a transcriptional repressor,the loss of Msx2 expression results in significant increases(P＜0.05 or P＜0.01)in the mRNA expression levels of integrin β2(Itgβ2),ItgαM,Itgα4,Rac family small GTPase 2(Rac2),Rac/Cdc42 guanine nucleo-tide exchange factor 6(Arhgef6)and protein tyrosine phosphatase receptor type C(Ptprc).CONCLUSION:Msx2 regu-lates cytoskeleton structure and cell-cell interaction through the Rho GTPases signaling pathway,thereby influencing the differentiation state of outer enamel epithelial cells.This study reveals the mechanism through which Msx2 regulates the differentiation of outer enamel epithelial cells,providing a theoretical foundation for the prevention and treatment of enam-el-related clinical dental diseases.

AIM:To investigate the mechanism by which muscle segment homeobox 2(Msx2)regulates the differentiation of outer enamel epithelial cells in the enamel organ.METHODS:Tissue paraffin sections were prepared and subjected to hematoxylin-eosin(HE)staining to analyze the effect of Msx2 deficiency on the differentiation status of epithelial cells in the enamel organ at the morphological level.At the ultrastructural level,alterations in cell structure were analyzed.The intermediate steps mediating cell differentiation were identified.Transcriptome sequencing analysis was performed to validate the molecular mechanisms underlying the observed phenomena.RESULTS:Msx2 deficiency was innovatively found to induce severe squamous epithelial hyperplasia in outer enamel epithelial cells of enamel organ,accompanied by dynamic restructuring of the cell cytoskeleton and alterations in cell adhesion at the ultrastructure level.As a transcriptional repressor,the loss of Msx2 expression results in significant increases(P＜0.05 or P＜0.01)in the mRNA expression levels of integrin β2(Itgβ2),ItgαM,Itgα4,Rac family small GTPase 2(Rac2),Rac/Cdc42 guanine nucleo-tide exchange factor 6(Arhgef6)and protein tyrosine phosphatase receptor type C(Ptprc).CONCLUSION:Msx2 regu-lates cytoskeleton structure and cell-cell interaction through the Rho GTPases signaling pathway,thereby influencing the differentiation state of outer enamel epithelial cells.This study reveals the mechanism through which Msx2 regulates the differentiation of outer enamel epithelial cells,providing a theoretical foundation for the prevention and treatment of enam-el-related clinical dental diseases.