title: The effect of delta-like 1 homologue on the proliferation and odontoblastic differentiation in human dental pulp stem cells.
abstract: BACKGROUND
  This study aimed to investigate the functions of delta-like homologue 1 (DLK1) in the proliferation and differentiation of human dental pulp stem cells (hDPSCs).
  
  
  METHODS
  Immunohistochemical analysis was used to determine the expression of alkaline phosphatase (ALP), dentin sialophosphoprotein (DSPP), DLK1, NOTCH1 and p-ERK1/2 in the mouse first maxillary molar. Recombinant lentivirus was constructed to overexpress DLK1 stably in hDPSCs. The cell viability and proliferation of hDPSCs were examined by CCK8 and EdU incorporation assay respectively. The odontoblastic differentiation of hDPSCs was determined by detection of ALPase activity assay, ALP and alizarin red staining and the expression of mineralization-related genes including ALP, DSPP and dental matrix protein. The mRNA and protein levels of DLK1 and p-ERK1/2 protein expression were detected. ERK inhibitor was used to test the differentiation effect of DLK1 on hDPSCs.
  
  
  RESULTS
  Delta-like homologue 1 was highly expressed on the odontoblasts and dental pulp cells on the first maxillary molar; the expression of p-ERK1/2 is similar with the DLK1 in the same process. The expression level of DLK1 increased significantly after the odontoblastic induction of hDPSCs. DLK1 overexpression increased the proliferation ability of hDPSCs and inhibited odontoblastic differentiation of hDPSCs. The protein level of p-ERK1/2 significantly increased in hDPSCs/dlk1-oe group. ERK signalling pathway inhibitor reversed the odontoblastic differentiation effects of DLK1 on hDPSCs.
  
  
  CONCLUSIONS
  The proliferation of hDPSCs was promoted after DLK1 overexpression. DLK1 inhibited the odontoblastic differentiation of hDPSCs, which maybe through ERK signalling pathway.
authors.affiliation: Department of Stomatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Shengcai
authors.initials: S
authors.lastname: Qi
authors.affiliation: Department of Pediatric Dentistry, School & Hospital of Stomatology, Tongji University, Shanghai Engineering Research Center of Tooth Restoration and Regeneration, Shanghai, China.
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Yan
authors.affiliation: Institute of Stomatology, Hospital of Stomatology, Nanjing Medical University, Nanjing, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Wen
authors.affiliation: Institute of Stomatology, Hospital of Stomatology, Nanjing Medical University, Nanjing, China.
authors.forename: Jialiang
authors.initials: J
authors.lastname: Li
authors.affiliation: Department of Stomatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Stomatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Fubo
authors.initials: F
authors.lastname: Chen
authors.affiliation: Department of Stomatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Xiaoshan
authors.initials: X
authors.lastname: Tang
authors.affiliation: Department of Stomatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Guangwei
authors.initials: G
authors.lastname: Shang
authors.affiliation: Department of Stomatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Yuanzhi
authors.initials: Y
authors.lastname: Xu
authors.affiliation: Department of Stomatology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai, China.
authors.forename: Raorao
authors.identifier: http://orcid.org/0000-0002-0224-3255
authors.initials: R
authors.lastname: Wang
mesh_terms: D000818:Animals; D002135:Calcium-Binding Proteins; D002454:Cell Differentiation; D049109:Cell Proliferation; D002478:Cells, Cultured; D003782:Dental Pulp / Q000166:cytology*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009804:Odontoblasts / Q000166:cytology* / Q000378:metabolism*; D013234:Stem Cells / Q000166:cytology*
chemical_list: D002135:Calcium-Binding Proteins; C512941:DLK1 protein, human; D036341:Intercellular Signaling Peptides and Proteins; D008565:Membrane Proteins