Role of osteoprotegerin in the regulation of dental epithelial-mesenchymal signaling during tooth development

Dental epithelial-mesenchymal signaling is crucial for tooth development, but the detailed mechanism is not fully understood. Using microarray analysis, it was revealed that the expression of osteoprotegerin, an important factor regulating bone remodeling, significantly increased after removal of the dental epithelium. Immunohistochemical staining revealed that osteoprotegerin expression within the dental mesenchyme was quite low during the prenatal period, but significantly increased after birth. To investigate the influence of osteoprotegerin upon tooth development, first-molar tooth germs from embryonic day 14.5 (E14.5) Chinese Kunming mice were treated with different concentrations of osteoprotegerin. It was revealed that osteoprotegerin could inhibit the expression of odontogenic markers while promoting the expression of osteogenic markers, thereby disrupting tooth morphogenesis. These findings were further supported by in vitro and in vivo cultures. Finally, quantitative reverse transcription-polymerase chain reaction and immunofluorescence studies revealed that, after osteoprotegerin treatment, the activity of the wingless/integrated (Wnt)/β-catenin pathway increased, indicating that increased osteoprotegerin expression in prenatal tooth development could lead to uncontrolled upregulation of the Wnt/β-catenin pathway.