Overexpressing the NH2-terminal fragment of dentin sialophosphoprotein (DSPP) aggravates the periodontal defects inDsppknockout mice.
OBJECTIVE
Previous studies have shown that dentin sialophosphoprotein (DSPP) is not only essential to the formation and mineralization of dentin but also plays an important role in forming and maintaining a healthy periodontium. Under physiological conditions, DSPP is proteolytically processed into the NH2-terminal and COOH-terminal fragments, and these fragments are believed to perform different functions in the mineralized tissues. Previous studies in our group have demonstrated that the NH2-terminal fragment of DSPP inhibits the formation and mineralization of dentin, while the role of this fragment in periodontium is unclear.


METHODS
We analyzed the periodontal tissues of the transgenic mice overexpressing the NH2-terminal fragment of DSPP in theDsppknockout background (referred to as "DsppKO/DSP Tg" mice), in comparison with wild type mice andDsppknockout mice. The approaches used in this study included histology, micro-computed tomography, back scattered scanning electron microscopy and resin-casted scanning electron microscopy.


RESULTS
DsppKO/DSP Tg mice exhibited a greater reduction of the alveolar bone, more remarkably altered canalicular systems around the osteocytes, less cementum, more radical migration of the epithelial attachment towards the apical direction, and more severe inflammation in molar furcation region, than in theDsppknockout mice.


CONCLUSIONS
Overexpressing the NH2-terminal fragment of DSPP worsened the periodontal defects inDsppknockout mice, indicating that the NH2-terminal fragment of DSPP may exert an inhibitory role in the formation and mineralization of hard tissues in the periodontium.
Department of Biomedical Sciences and Center for Craniofacial Research and Diagnosis, Texas A&M University Baylor College of Dentistry, 3302 Gaston Avenue, Dallas, TX 75246, USA.
Monica Prasad
MP
Gibson
Department of Biomedical Sciences and Center for Craniofacial Research and Diagnosis, Texas A&M University Baylor College of Dentistry, 3302 Gaston Avenue, Dallas, TX 75246, USA.
Priyam
P
Jani
Department of Biomedical Sciences and Center for Craniofacial Research and Diagnosis, Texas A&M University Baylor College of Dentistry, 3302 Gaston Avenue, Dallas, TX 75246, USA.
Xiaofang
X
Wang
Department of Biomedical Sciences and Center for Craniofacial Research and Diagnosis, Texas A&M University Baylor College of Dentistry, 3302 Gaston Avenue, Dallas, TX 75246, USA.
Yongbo
Y
Lu
Department of Biomedical Sciences and Center for Craniofacial Research and Diagnosis, Texas A&M University Baylor College of Dentistry, 3302 Gaston Avenue, Dallas, TX 75246, USA.
Chunlin
C
Qin
Bone biology; Cell biology; Cementum; Gene regulation; Periodontitis