Dentin sialoprotein facilitates dental mesenchymal cell differentiation and dentin formation

Wentong Li,Lisa Shoff,Shuo Chen,Lian Wu,Junsheng Feng,Xin Li,Feng Wang,Lei Chen,Zhuo Chen,Kevin J Donly,Mary Macdougall

doi:10.1038/s41598-017-00339-w

Abstract

Dentin sialoprotein (DSP) is a dentin extracellular matrix protein. It is involved in dental mesenchymal cell lineages and dentin formation through regulation of its target gene expression. DSP mutations cause dentin genetic diseases. However, mechanisms of DSP in controlling dental mesenchymal cell differentiation are unknown. Using DSP as bait, we screened a protein library from mouse odontoblastic cells and found that DSP is a ligand and binds to cell surface receptor, occludin. Further study identified that the C-terminal DSP domainaa 363–458 interacts with the occludin extracellular loop 2aa 194–241. The C-terminal DSP domain induced phosphorylation of occludin Ser490 and focal adhesion kinase (FAK) Ser722 and Tyr576. Coexpression of DSP, occludin and FAK was detected in dental mesenchymal cells during tooth development. Occludin physically interacts with FAK, and occludin and FAK phosphorylation can be blocked by DSP and occludin antibodies. This DSP domain facilitates dental mesenchymal cell differentiation and mineralization. Furthermore, transplantation and pulp-capping procedures revealed that this DSP domain induces endogenous dental pulp mesenchymal cell proliferation, differentiation and migration, while stimulating blood vessel proliferation. This study elucidates the mechanism of DSP in dental mesenchymal lineages and implies that DSP may serve as a therapeutic agent for dentin-pulp complex regeneration in dental caries.

Highlights

Craniofacial skeleton is original from neural crest-derived mesenchymal cells[1]
To identify whether dentin sialoprotein (DSP) interacts with other proteins, we generated Glutathione fusion protein (GST)-DSP fusion protein (Fig. 1A,B), and cell lysis was isolated from mouse odontoblast-like cells
These results showed that the COOHterminal DSP domainaa 363–458 (DSPf5) interacts with the extracellular loop 2 of Oclnaa 194–241 (OclnL2) (Fig. 1E–H)

Summary

Introduction

Craniofacial skeleton is original from neural crest-derived mesenchymal cells[1] These cells proliferate and differentiate into odontoblasts and osteoblasts as well as build dynamic mineralized tissues such as bone and dentin. Among the NCPs, a family of small integrin-binding ligand N-linked glycoproteins (SIBLINGs) comprises bone sialoprotein (BSP), dentin matrix protein 1 (DMP1) and dentin sialophosphoprotein (DSPP), matrix extracellular phosphoglycoprotein (MEPE) and osteopontin (OPN) These SIBLING genes are highly expressed in mineralizing tissues related to tooth and bone development and believed to be responsible for initiating and modulating cell differentiation and mineralization processes via matrix-cell interaction. An Arg-Gly-Asp (RGD) triple peptide within several NCPs regulates intracellular signal pathways via cell membrane receptors such as integrin[4] Despite their common origin, dentin and bone are dramatically different from their morphologies and physical functions. Whether the signaling pathways by which DSP regulates intracellular activity via Ocln is not clearly understood

Methods

Results

Conclusion