title: IGFBP5 enhances osteogenic differentiation potential of periodontal ligament stem cells and Wharton's jelly umbilical cord stem cells, via the JNK and MEK/Erk signalling pathways.
abstract: OBJECTIVE
  Mesenchymal stem cell (MSC)-mediated tissue regeneration represents a promising strategy for repair of tissue defects, but its molecular mechanisms remain unclear, restricting the use of MSCs. Our previous study indicated that insulin-like growth factor-binding protein 5 (IGFBP5) exerted a valuable effect on osteogenic differentiation of MSCs, but its molecular mechanisms underlying directed differentiation remained unclear. In this study, we have investigated the molecular role of IGFBP5 in regulating this osteogenic differentiation potential.
  
  
  METHODS
  Periodontal ligament stem cells (PDLSCs) were isolated from periodontal ligament tissue. Wharton's jelly of umbilical cord stem cells (WJCMSCs) was obtained commercially. Lentiviral IGFBP5 shRNA was used to silence IGFBP5. Retroviruses expressing wild-type IGFBP5 were used to overexpress IGFBP5 in the WJCMSCs. Recombinant human IGFBP5 protein (rhIGFBP5) was used to treat PDLSCs for 24 h. Western blot analysis was used to detect the MAPK signalling pathway, and alkaline phosphatase (ALP) activity, Alizarin Red staining and quantitative calcium analysis were used to study osteogenic differentiation potentials.
  
  
  RESULTS
  Overexpression of IGFBP5 or rhIGFBP5 increased expression levels of phosphorylated c-Jun N-terminal kinase (p-JNK), phosphorylated mitogen-activated protein kinase 1 and 2 (p-MEK1/2) and phosphorylated extracellular regulated protein kinases (p-Erk1/2) in both WJCMSCs and PDLSCs. Consistently, silenced IGFBP5 was found to effectively inhibit expression of p-JNK, p-Erk1/2 and p-MEK1/2 in PDLSCs and WJCMSCs. Furthermore, inhibition of JNK by its inhibitor, SP600125, or MEK/Erk signalling by its inhibitor, PD98059, dramatically blocked IGFBP5-enhanced ALP activity and in vitro mineralization in both PDLSCs and WJCMSCs.
  
  
  CONCLUSIONS
  Our results demonstrated that IGFBP5 promoted osteogenic differentiation potentials of PDLSCs and WJCMSCs via the JNK and MEK/Erk signalling pathways.
authors.affiliation: Department of Endodontics, Tianjin Medical University School of Stomatology, Tianjin, China.|Laboratory of Molecular Signaling and Stem Cells Therapy, Beijing Key Laboratory of Tooth Regeneration and Function Reconstruction, Capital Medical University School of Stomatology, Beijing, China.
authors.forename: Yuejun
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Endodontics, Tianjin Medical University School of Stomatology, Tianjin, China.
authors.forename: Zhi
authors.initials: Z
authors.lastname: Jia
authors.affiliation: Laboratory of Molecular Signaling and Stem Cells Therapy, Beijing Key Laboratory of Tooth Regeneration and Function Reconstruction, Capital Medical University School of Stomatology, Beijing, China.
authors.forename: Shu
authors.initials: S
authors.lastname: Diao
authors.affiliation: Laboratory of Molecular Signaling and Stem Cells Therapy, Beijing Key Laboratory of Tooth Regeneration and Function Reconstruction, Capital Medical University School of Stomatology, Beijing, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Lin
authors.affiliation: Department of Stomatology, Beijing Shijitan hospital, Capital Medical University, Beijing, China.
authors.forename: Xiaomeng
authors.initials: X
authors.lastname: Lian
authors.affiliation: Laboratory of Molecular Signaling and Stem Cells Therapy, Beijing Key Laboratory of Tooth Regeneration and Function Reconstruction, Capital Medical University School of Stomatology, Beijing, China.
authors.forename: Liping
authors.initials: L
authors.lastname: Wang
authors.affiliation: Laboratory of Molecular Signaling and Stem Cells Therapy, Beijing Key Laboratory of Tooth Regeneration and Function Reconstruction, Capital Medical University School of Stomatology, Beijing, China. dongrui95@126.com.
authors.forename: Rui
authors.initials: R
authors.lastname: Dong
authors.affiliation: Department of Endodontics, Tianjin Medical University School of Stomatology, Tianjin, China. dyliuperio@tmu.edu.cn.|Molecular Laboratory for Gene Therapy and Tooth Regeneration, Beijing Key Laboratory of Tooth Regeneration and Function Reconstruction, Capital Medical University School of Stomatology, Beijing, China. dyliuperio@tmu.edu.cn.
authors.forename: Dayong
authors.initials: D
authors.lastname: Liu
authors.affiliation: Laboratory of Molecular Signaling and Stem Cells Therapy, Beijing Key Laboratory of Tooth Regeneration and Function Reconstruction, Capital Medical University School of Stomatology, Beijing, China. zpfan@ccmu.edu.cn.
authors.forename: Zhipeng
authors.initials: Z
authors.lastname: Fan
mesh_terms: D000293:Adolescent; D000328:Adult; D002454:Cell Differentiation; D002460:Cell Line; D002478:Cells, Cultured; D006801:Humans; D018975:Insulin-Like Growth Factor Binding Protein 5 / Q000378:metabolism*; D020935:MAP Kinase Signaling System; D008297:Male; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000378:metabolism; D010012:Osteogenesis; D010513:Periodontal Ligament / Q000166:cytology* / Q000378:metabolism; D010766:Phosphorylation; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D014470:Umbilical Cord / Q000166:cytology* / Q000378:metabolism; D059631:Wharton Jelly / Q000166:cytology* / Q000378:metabolism; D055815:Young Adult
chemical_list: D018975:Insulin-Like Growth Factor Binding Protein 5