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1.  LOSS OF DENTIN SIALOPHOSPHOPROTEIN (DSPP) LEADS TO PERIODONTAL DISEASES IN MICE 
Journal of periodontal research  2012;48(2):221-227.
Background and Objective
Dentin sialophosphoprotein (DSPP) and its cleaved products, dentin phosphoprotein (DPP) and dentin sialoprotein (DSP), play important roles in biomineralization. Recently, we observed that DSPP is highly expressed in the alveolar bone and cementum, indicating that this molecule may play an important role in the formation and maintenance of a healthy periodontium, and its deletion may cause increased susceptibility to periodontal diseases. The objective of this investigation was to study the effects of Dspp ablation on periodontal tissues by analyzing Dspp null mice.
Methods
Newborn to 6-month-old Dspp null mice were examined, and the 3-month and 6-month-old Dspp null mice were characterized in detail using X-ray radiography, histology and scanning electron microscopy (backscattered as well as resin-infiltrating). Wild-type mice of the same age groups served as the normal controls.
Results
The Dspp null mice showed a significant loss of alveolar bone and cementum, particularly in the furcation and the interproximal regions of the molars. The alveolar bone appeared more porous while the quantity of cementum was reduced in the apical region. The canalicular systems and osteocytes in the alveolar bone were abnormal, with reduced numbers of canaliculi and an altered osteocyte morphology. The loss of alveolar bone and cementum along with the detachment of the periodontal ligaments (PDL) led to the apical migration of the epithelial attachment and the formation of periodontal pockets.
Conclusion
Inactivation of DSPP leads to the loss of the alveolar bone and cementum and increased susceptibility to bacterial infections in the PDL of Dspp null mice. The fact that the loss of DSPP results in periodontal diseases indicates that this molecule plays a vital role in maintaining the health of the periodontium.
doi:10.1111/j.1600-0765.2012.01523.x
PMCID: PMC3514631  PMID: 22934831
2.  TWIST1 Promotes the Odontoblast-like Differentiation of Dental Stem Cells 
Advances in Dental Research  2011;23(3):280-284.
Stem cells derived from the dental pulp of extracted human third molars (DPSCs) have the potential to differentiate into odontoblasts, osteoblasts, adipocytes, and neural cells when provided with the appropriate conditions. To advance the use of DPSCs for dentin regeneration, it is important to replicate the permissive signals that drive terminal events in odontoblast differentiation during tooth development. Such a strategy is likely to restore a dentin matrix that more resembles the tubular nature of primary dentin. Due to the limitations of culture conditions, the use of ex vivo gene therapy to drive the terminal differentiation of mineralizing cells holds considerable promise. In these studies, we asked whether the forced expression of TWIST1 in DPSCs could alter the potential of these cells to differentiate into odontoblast-like cells. Since the partnership between Runx2 and Twist1 proteins is known to control the onset of osteoblast terminal differentiation, we hypothesized that these genes act to control lineage determination of DPSCs. For the first time, our results showed that Twist1 overexpression in DPSCs enhanced the expression of DSPP, a gene that marks odontoblast terminal differentiation. Furthermore, co-transfection assays showed that Twist1 stimulates Dspp promoter activity by antagonizing Runx2 function in 293FT cells. Analysis of our in vitro data, taken together, suggests that lineage specification of DPSCs can be modulated through ex vivo gene modifications.
doi:10.1177/0022034511405387
PMCID: PMC3144037  PMID: 21677079
TWIST1; RUNX2; dental stem cells; gene transfer; odontoblast; tooth development

Results 1-2 (2)