title: GSK3β is a checkpoint for TNF-α-mediated impaired osteogenic differentiation of mesenchymal stem cells in inflammatory microenvironments.
abstract: BACKGROUND
  The fate and differentiation of mesenchymal stem cells (MSCs) depend on various microenvironmental cues. In chronic inflammatory bone disease, bone regeneration is inhibited. The present study therefore sought to identify the underlying molecule mechanisms.
  
  
  METHODS
  We isolated periodontal ligament stem cells (PDLSCs), a new population of MSCs, from the periodontal ligament tissues of periodontitis patients and healthy controls (p-PDLSCs and h-PDLSCs). The secretion of inflammatory cytokines, like TNF-α, IL-1β, IL-6 and IL-8, after LPS stimulation was measured by ELISA. The expressions of p-GSK3β and GSK3β in two types of PDLSCs were detected by Western blot. TOPFlash was used to assay the Tcf/Lef transcriptional activity. Knockdown of GSK3β by siRNA and over-expression of GSK3β by adenoviruses were performed to confirm the role of GSK3β in the impaired osteogenic differentiation of PDLSCs under inflammatory microenvironment.
  
  
  RESULTS
  We demonstrated that p-PDLSCs displayed impaired osteogenic capacity than h-PDLSCs. Upon inflammatory stimulation, monocytes, but not PDLSCs, released inflammatory cytokines among which TNF-α directly act on PDLSCs and suppressed their osteogenic differentiation. TNF-α induced the phosphorylation of GSK3β, the deactivated form of GSK3β, which increased nuclear β-catenin and Lef-1 accumulation, and eventually reduced the Runx2-associated osteogenesis in PDLSCs. Over-expression of GSK3β rescued osteogenesis in TNF-α-stimulated PDLSCs, whereas inactivation of GSK3β was sufficient to liberate the β-catenin/Lef-1/Runx2 pathway.
  
  
  CONCLUSIONS
  GSK3β plays an obligatory role in the TNF-α-mediated inhibition of osteogenesis in MSCs.
  
  
  CONCLUSIONS
  The strategy to target GSK3β may provide a potential approach to bone regeneration in inflammatory microenvironments.
authors.affiliation: Department of Orthodontics, School of Stomatology, Fourth Military Medical University, Xi'an, China; Research and Development Center for Tissue Engineering, Fourth Military Medical University, Xi'an, China; Department of Stomatology, Nanjing Bayi Hospital, Nanjing, China.
authors.forename: Xiangwei
authors.initials: X
authors.lastname: Kong
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.forename: Ruidong
authors.initials: R
authors.lastname: Ye
authors.forename: Bin
authors.initials: B
authors.lastname: Zhu
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zhu
authors.forename: Xianghui
authors.initials: X
authors.lastname: Liu
authors.forename: Chenghu
authors.initials: C
authors.lastname: Hu
authors.forename: Hailang
authors.initials: H
authors.lastname: Luo
authors.forename: Yongjie
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yin
authors.initials: Y
authors.lastname: Ding
authors.forename: Yan
authors.initials: Y
authors.lastname: Jin
mesh_terms: D000328:Adult; D002454:Cell Differentiation / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D050659:Core Binding Factor Alpha 1 Subunit / Q000378:metabolism; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D000071679:Glycogen Synthase Kinase 3 beta; D006801:Humans; D007249:Inflammation / Q000378:metabolism / Q000473:pathology*; D007378:Interleukins / Q000378:metabolism; D051821:Lymphoid Enhancer-Binding Factor 1 / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000378:metabolism / Q000473:pathology*; D009000:Monocytes / Q000378:metabolism / Q000473:pathology; D010012:Osteogenesis / Q000502:physiology*; D010513:Periodontal Ligament / Q000378:metabolism / Q000473:pathology; D010518:Periodontitis / Q000378:metabolism / Q000473:pathology; D010766:Phosphorylation / Q000502:physiology; D055153:Stem Cell Niche / Q000502:physiology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D055815:Young Adult; D051176:beta Catenin / Q000378:metabolism
chemical_list: D050659:Core Binding Factor Alpha 1 Subunit; D007378:Interleukins; C497573:LEF1 protein, human; D051821:Lymphoid Enhancer-Binding Factor 1; C493709:RUNX2 protein, human; D014409:Tumor Necrosis Factor-alpha; D051176:beta Catenin; C000605506:GSK3B protein, human; D000071679:Glycogen Synthase Kinase 3 beta; D038362:Glycogen Synthase Kinase 3
keywords: Glycogen synthase kinase 3β; Mesenchymal stem cell; Osteogenic differentiation; Tumor necrosis factor-α