Dentin sialophosphoprotein-derived proteins in porcine pulp and dentin - Gene expression and function

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• 作者：Ryuji Yamamoto ^{yamamoto-rj@tsurumi-u.ac.jp" class="auth_mail" title="E-mail the corresponding author} ; Yasuo Yamakoshi ; ^{yamakoshi-y@tsurumi-u.ac.jp" class="auth_mail" title="E-mail the corresponding author}
• 关键词：ALP ; alkaline phosphatase ; BMP ; bone morphogenic protein ; ELISA ; enzyme-linked immunosorbent assay ; HPLC ; high performance liquid chromatography ; MMP ; matrix metalloproteinase ; qPCR ; quantitative polymerase chain reaction ; RT-PCR ; reverse transcription-polymerase chain reaction ; SDS-PAGE ; sodium dodecyl sulfate-polyacrylamide gel electrophoresis ; TGF-β ; transforming growth factor-beta
• 刊名：Journal of Oral Biosciences
• 出版年：2016
• 出版时间：November 2016
• 年：2016
• 卷：58
• 期：4
• 页码：120-127
• 全文大小：2298 K

文摘

Dentin sialophosphoprotein (DSPP) is the most abundant non-collagenous protein in dentin and is critical for the proper mineralization of tooth dentin. DSPP is processed by proteases into three major domains: dentin sialoprotein (DSP), dentin glycoprotein (DGP) and dentin phosphoprotein (DPP). Two mRNA variants are expressed from the Dspp gene. The larger transcript encodes full-length DSPP (DSP+DGP+DPP). The shorter transcript encodes only DSP.

Highlight

We fractionated DSPP-derived proteins from the dental pulp of developing porcine incisors using heparin chromatography. DSP was identified, but little DPP could be detected in any fraction. Expression of full-length Dspp mRNA, determined by qPCR analysis, was significantly higher in odontoblasts than in pulp. Expression of DSP-only mRNA was almost equal in odontoblasts and in the body of pulp. Expression of full-length Dspp mRNA was also significantly higher than expression of DSP-only mRNA in odontoblasts. Both the full-length and DSP-only Dspp mRNA showed only trace expression in the pulp tip. We purified TGF-β1-unbound or -bound to DPP and DSP using high performance liquid chromatography (HPLC) and measured its alkaline phosphatase stimulating activity in human periodontal cells with or without TGF-β receptor inhibitor. We also incubated carrier-free human recombinant TGF-β1 (CF-hTGF-β1) protein with TGF-β1-unbound DPP or DSP and characterized binding ability.

Conclusion

DSP-only is expressed throughout odontoblast differentiation, while full-length DSPP is predominantly expressed by odontoblasts only after they have differentiated from mesenchymal cells. DPP and DSP rescued the loss of TGF-β1 activity. Type I collagen was infrequently bound to CF-hTGF-β1.