DSPP Is Essential for Normal Development of the Dental-Craniofacial Complex.
The craniofacial skeleton is derived from both neural crest cells and mesodermal cells; however, the majority of the bone, cartilage, and connective tissue is derived from the neural crest. Dentin sialophosphoprotein (DSPP) is a precursor protein that is expressed by the connective tissues of the craniofacial skeleton, namely, bone and dentin with high expression levels in the dentin matrix. Gene ablation studies have shown severe dental defects in DSPP-null mutant mice. Therefore, to elucidate the role of DSPP on the developing dental-craniofacial complex, we evaluated phenotypic changes in the structure of intramembranous bone and dentin mineralization using 3 different age groups of DSPP-null and wild-type mice. Results from micro-computed tomographic, radiographic, and optical microscopic analyses showed defective dentin, alveolar and calvarial bones, and sutures during development. The impaired mineralization of the cranial bone correlated well with low expression levels of Runx2, Col1, and OPN identified using calvarial cells from DSPP-null and wild-type mice in an in vitro culture system. However, the upregulation of MMP9, MMP2, FN, and BSP was observed. Interestingly, the null mice also displayed low serum phosphate levels, while calcium levels remained unchanged. Alizarin red and von Kossa staining confirmed the dysfunction in the terminal differentiation of osteoblasts obtained from the developing calvaria of DSPP-null mice. Immunohistochemical analysis of the developing molars showed changes in Runx2, Gli1, Numb, and Notch expression in the dental pulp cells and odontoblasts of DSPP-null mice when compared with wild-type mice. Overall, these observations provide insight into the role of DSPP in the normal development of the calvaria, alveolar bone, and dentin-pulp complex.
Brodie Tooth Development Genetics and Regenerative Medicine Research Laboratory, Department of Oral Biology, University of Illinois at Chicago, Chicago, IL, USA.
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Chen
Brodie Tooth Development Genetics and Regenerative Medicine Research Laboratory, Department of Oral Biology, University of Illinois at Chicago, Chicago, IL, USA.
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Zhang
Brodie Tooth Development Genetics and Regenerative Medicine Research Laboratory, Department of Oral Biology, University of Illinois at Chicago, Chicago, IL, USA.
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Ramachandran
Brodie Tooth Development Genetics and Regenerative Medicine Research Laboratory, Department of Oral Biology, University of Illinois at Chicago, Chicago, IL, USA anneg@uic.edu.
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George
D000539:Alveolar Process / Q000002:abnormalities; D000818:Animals; D002113:Calcification, Physiologic / Q000502:physiology; D024042:Collagen Type I / Q000032:analysis; D050659:Core Binding Factor Alpha 1 Subunit / Q000032:analysis; D003393:Cranial Sutures / Q000002:abnormalities; D003804:Dentin / Q000002:abnormalities; D003810:Dentinogenesis / Q000502:physiology; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000502:physiology*; D005147:Facial Bones / Q000002:abnormalities / Q000254:growth & development*; D005353:Fibronectins / Q000032:analysis; D058574:Integrin-Binding Sialoprotein / Q000032:analysis; D051741:Kruppel-Like Transcription Factors / Q000032:analysis; D020778:Matrix Metalloproteinase 2 / Q000032:analysis; D020780:Matrix Metalloproteinase 9 / Q000032:analysis; D008565:Membrane Proteins / Q000032:analysis; D051379:Mice; D009154:Mutation / Q000235:genetics; D009419:Nerve Tissue Proteins / Q000032:analysis; D009805:Odontogenesis / Q000502:physiology*; D009924:Organ Culture Techniques; D010006:Osteoblasts / Q000473:pathology; D053495:Osteopontin / Q000032:analysis; D010710:Phosphates / Q000097:blood; D010750:Phosphoproteins / Q000235:genetics / Q000502:physiology*; D051880:Receptors, Notch / Q000032:analysis; D012795:Sialoglycoproteins / Q000235:genetics / Q000502:physiology*; D012886:Skull / Q000002:abnormalities / Q000254:growth & development*; D000071676:Zinc Finger Protein GLI1; D000099311:Dentin Sialophosphoprotein
D024042:Collagen Type I; D050659:Core Binding Factor Alpha 1 Subunit; D016326:Extracellular Matrix Proteins; D005353:Fibronectins; D058574:Integrin-Binding Sialoprotein; D051741:Kruppel-Like Transcription Factors; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D053495:Osteopontin; D010710:Phosphates; D010750:Phosphoproteins; D051880:Receptors, Notch; D012795:Sialoglycoproteins; D000071676:Zinc Finger Protein GLI1; D000099311:Dentin Sialophosphoprotein; C498520:Gli1 protein, mouse; C546872:Ibsp protein, mouse; C106293:Numb protein, mouse; C493716:Runx2 protein, mouse; C506896:Spp1 protein, mouse; C522362:Mmp2 protein, mouse; C501830:Mmp9 protein, mouse
calvaria; dental pulp; dentin sialophosphoprotein; mandible; mineralization; odontoblasts