Circadian Disruption Affects Dentin Development Via DSP Nuclear Translocation

This study aims to investigate how circadian rhythm disruption induces nuclear translocation of dentin sialoprotein(DSP), exploring its molecular mechanism and its functional impact on odontoblasts and dentin development. Wild type C57 male mice at 8 weeks and 7 days of age were divided into 2 groups respectively: one group maintained normal circadian rhythm, while the other group induced circadian rhythm disruption by changing environmental light. Notch assay was performed to measure the growth speed of the inicisors and Micro-CT was used to estimate the development of molars. Protein nuclear translocation in pre-odontoblasts and dental pulp cells were observed via immunofluorescence. Western blot and Co-Immunoprecipitation were used to confirm the molecular mechanism of DSP nuclear translocation. To assess DSP nuclear translocation resulted pathway alterations, RNA sequencing was performed in mDPC6T cell line with DSP-NLS. Circadian disruption triggered bigger size of molars and higher growth speed of incisors, correlating with aberrant nuclear accumulation of DSP in pre-odontoblasts and pulp cells. RNA sequencing showed nuclear-located DSP could induce an increase of cell proliferation and different changes in the expression of several critical transcriptional factors. Circadian rhythm disruption induces DSP nuclear translocation, revealing a non-canonical nuclear signaling role for DSP that could mediate pre-odontoblast proliferation and dentinogenesis.