The canonical BMP signaling pathway plays a crucial part in stimulation of dentin sialophosphoprotein expression by BMP-2.
Dentin sialophosphoprotein (DSPP), a typical dentin-specific protein, is mainly expressed in the dentin extracellular matrix and plays a role in dentin mineralization. BMP-2 provides a strong signal for differentiation and mineralization of odontoblasts and osteoblasts. Previously, BMP-2 treatment is reported to stimulate Dspp expression in the MD10-F2 pre-odontoblast cells through activation of the heterotrimeric transcription factor Y (NF-Y). The canonical BMP signaling pathway is known to contribute greatly to biomineralization, however, it is not known whether it is involved in Dspp expression. Here, we investigated this question. Activation of the canonical BMP-2 signaling pathway in MDPC-23, preodontoblast cell, by overexpression of constitutively active Smad1/5 or downstream transcription factors Dlx5 and Runx2 stimulated Dspp expression. Conversely, knockdown of each element with siRNA significantly blocked the BMP-2-induced Dspp expression. To test whether these transcription factors downstream of BMP-2 are directly involved in regulating Dspp, we analyzed the mouse Dspp promoter. There are 5 well conserved homeodomain binding elements, H1 to H5, in Dspp proximal promoter regions (-791 to +54). A serial deletion of H1 and H2 greatly changed basal promoter activity and responsiveness to Dlx5 or Msx2. However, further deletions did not change the responsiveness to Dlx5 or Msx2. H1 and H2 sites can be suggested as specific response elements of Dlx5 and Msx2, respectively, based on their promoter activity modulation. Thus, the canonical BMP-2 signaling pathway plays a crucial part in the regulation of Dspp expression through the action of Smads, Dlx5, Runx2, and Msx2.
Cho
Young-Dan
YD
Department of Molecular Genetics, School of Dentistry and Dental Research Institute, BK21 Program, Seoul National University, Seoul 110-749, Korea.
Yoon
Won-Joon
WJ
Woo
Kyung-Mi
KM
Baek
Jeong-Hwa
JH
Park
Joo-Cheol
JC
Ryoo
Hyun-Mo
HM
D000818:Animals; D015153:Blotting, Western; D055396:Bone Morphogenetic Protein 2 / Q000235:genetics / Q000378:metabolism*; D002454:Cell Differentiation; D002478:Cells, Cultured; D050659:Core Binding Factor Alpha 1 Subunit / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D024202:Electrophoretic Mobility Shift Assay; D016326:Extracellular Matrix Proteins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D009804:Odontoblasts / Q000166:cytology / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics; D034741:RNA, Small Interfering / Q000494:pharmacology; D020218:Response Elements / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012795:Sialoglycoproteins / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction; D051899:Smad2 Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D051900:Smad3 Protein / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D000099311:Dentin Sialophosphoprotein
D055396:Bone Morphogenetic Protein 2; D050659:Core Binding Factor Alpha 1 Subunit; D016326:Extracellular Matrix Proteins; D018398:Homeodomain Proteins; D008156:Luciferases; D010750:Phosphoproteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D012795:Sialoglycoproteins; D051899:Smad2 Protein; D051900:Smad3 Protein; D000099311:Dentin Sialophosphoprotein; C501120:Dlx5 protein, mouse; C084119:MSX2 protein; C493716:Runx2 protein, mouse; C497783:Smad2 protein, mouse; C497791:Smad3 protein, mouse