Nicotinamide Improves Delayed Tooth Eruption in Runx2 Mice

Area of Science:

• Genetics and Molecular Biology
• Developmental Biology
• Pharmacology

Background:

• Cleidocranial dysplasia (CCD) causes severe dental anomalies, including delayed tooth eruption.
• Current treatments involve invasive surgical and orthodontic interventions due to a lack of medication.
• The RUNX2 gene is crucial for bone and tooth development, and its mutations lead to CCD.

Purpose of the Study:

• To investigate the therapeutic potential of nicotinamide for delayed tooth eruption in a mouse model of CCD.
• To elucidate the molecular mechanisms by which nicotinamide affects osteoclastogenesis and tooth eruption.
• To identify nicotinamide as a potential drug candidate for dental abnormalities in CCD.

Main Methods:

• Utilized the Runx2-deficient (Runx2-/-) mouse model, a standard model for CCD.
• Administered nicotinamide to assess its effects on delayed tooth eruption and osteoclastogenesis.
• Analyzed gene and protein expression levels of key factors including RUNX2, CSF1, RANKL, and OPG.
• Investigated the regulatory role of RUNX2 in Csf1 gene expression and the impact of nicotinamide on RUNX2 activity.

Main Results:

• Nicotinamide significantly improved delayed tooth eruption in Runx2-/- mice.
• Treatment with nicotinamide restored osteoclastogenesis by increasing RUNX2 and CSF1 expression and the RANKL/OPG ratio.
• RUNX2 was found to directly regulate Csf1 gene expression.
• Nicotinamide enhanced RUNX2 protein levels and activity through Sirt2 inhibition.

Conclusions:

• Nicotinamide demonstrates significant therapeutic potential for treating delayed tooth eruption in CCD.
• The study reveals the underlying molecular mechanism involving the restoration of osteoclastogenesis via RUNX2 and CSF1 regulation.
• Nicotinamide is proposed as a promising candidate drug for addressing dental abnormalities associated with cleidocranial dysplasia.