IADR Abstract Archives

Pi promotes apoptosis and typeIII sodium-dependent phosphate-cotransporters in odontoblast-like cells

During dental carious development, tooth dentin demineralization leads to local release of inorganic phosphate (Pi) within dental tubuli.

Aim: As odontoblasts represent the first cellular barrier during carious establishment, the aim of this study was to determine the effects of Pi on odontoblast behaviour as well as on sodium dependent phosphate cotransporters known to be key regulators of phosphate homeostasis.

Materials and methods: Using murine odontoblast-like cell line MO6-G3, experiments were designed to determine cell proliferation (by cell counting), cell viability (by MTS) and apoptosis (by Hoechst staining and caspase-3 activity assay) without (control) or with an increased concentration (1 to 10mM) of Pi. In addition, we deciphered by real-time RT-PCR, the effects of treatment of 1mM or 10Mm of Pi on the expression of type III sodium dependent phosphate cotransporters (Glvr-1 and 2) compared to the control without Pi. Statistical analysis; one-way ANOVA Newman-Keuls'test or t-test.

Results: compared to the control, high Pi concentration treatment (10mM) significantly alters odontoblast viability (p<0.05) and promote apoptosis through a mechanism dependent on calcium/phosphate crystal formation, analysed by Transmission Electron Microscopy and mass spectrometry. Moreover, we revealed, for the first time, that Glvr-1 and 2 expressed in odontoblast-like cells are significantly upregulated (p<0.05) by 10mM of Pi treatment compared to the control. This increase of phosphate cotransporters expressions was correlated with ERK1/2 phophorylation (observed by Western blot) and crystal formation. In calcium-free culture conditions or in presence of the specific inhibitor of ERK phosphorylation (UO126), Glvr-1 and -2 expressions failed to increase, demonstrating that Pi effects on Glvr-1 and -2 require the presence of calcium and involve ERK signalling pathways.

Conclusion: This study contributes to give new insights in the effects of Pi during carious diseases.

Authors acknowledge Dr Mary MacDougall who kindly provided the MO6-G3

This study was supported by IFRO


IADR/AADR/CADR General Session
2009 IADR/AADR/CADR General Session (Miami, Florida)
Miami, Florida
2009
124
Pulp Biology & Regeneration Research
  • Wittrant, Yohan  ( INSERM U791, Nantes, N/A, France )
  • Guicheux, Jérome  ( INSERM U791, Nantes, N/A, France )
  • Bourgine, Annabelle  ( INSERM U791, Nantes, N/A, France )
  • Alliot-licht, Brigitte  ( INSERM U791, Nantes, N/A, France )
  • Khosniat, Solmaz  ( INSERM U791, Nantes, N/A, France )
  • Masson, Martial  ( INSERM U791, Nantes, N/A, France )
  • Gatius, Maithé  ( INSERM U791, Nantes, N/A, France )
  • Rouillon, Thierry  ( INSERM U791, Nantes, N/A, France )
  • Weiss, Pierre  ( INSERM U791, Nantes, N/A, France )
  • Beck, Laurent  ( INSERM U845, Paris, N/A, France )
    • Oral Session
    Dentin Dysplasia, Aging of Pulp Cells, and Endodontic Outcomes
    04/01/2009