title: Dose-specific effects of tumor necrosis factor alpha on osteogenic differentiation of mesenchymal stem cells.
abstract: OBJECTIVE
  To investigate tumor necrosis factor alpha (TNF-α)-induced changes in osteogenic differentiation from mesenchymal stem cells (MSCs).
  
  
  METHODS
  Blockade of nuclear factor-κB (NF-κB) was achieved in ST2 murine MSCs via overexpression of the NF-κB inhibitor, IκBα. Osteogenic differentiation was induced in IκBα-overexpressing ST2 cells and normal ST2 cells when these cells were treated with TNF-α at various concentrations. Expression levels of bone marker genes were determined using real time RT-PCR and ALP activity assay. In vitro mineralization was performed to determine long-term exposure to TNF-α on mineral nodule formation. MTT assay was used to determine the changes in cell proliferation/survival.
  
  
  RESULTS
  Levels of Runx2, Osx, OC and ALP were up-regulated in cell cultures treated with TNF-α at lower concentrations, while down-regulated in cell cultures treated with TNF-α at higher concentrations. Blockade of NF-κB signaling reversed the inhibitory effect observed in cell cultures treated with TNF-α at higher concentrations, but showed no effect on cell cultures treated with TNF-α at lower concentrations. In contrast, long-term treatment of TNF-α at all concentrations induced inhibitory effects on in vitro mineral nodule formation. MTT assay showed that TNF-α inhibits proliferation/survival of mesenchymal stem cells when the NF-κB signaling pathway is blocked.
  
  
  CONCLUSIONS
  The binding of TNF-α to its receptors results in the activation of multiple signaling pathways, which actively interact with each other to regulate the differentiation, proliferation, survival and apoptosis of MSCs.
authors.affiliation: Department of Periodontology, School of Dentistry, Shandong University, Jinan, China.
authors.forename: H
authors.initials: H
authors.lastname: Huang
authors.forename: N
authors.initials: N
authors.lastname: Zhao
authors.forename: X
authors.initials: X
authors.lastname: Xu
authors.forename: Y
authors.initials: Y
authors.lastname: Xu
authors.forename: S
authors.initials: S
authors.lastname: Li
authors.forename: J
authors.initials: J
authors.lastname: Zhang
authors.forename: P
authors.initials: P
authors.lastname: Yang
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001483:Base Sequence; D002113:Calcification, Physiologic / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D050659:Core Binding Factor Alpha 1 Subunit / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D015870:Gene Expression / Q000187:drug effects; D005819:Genetic Markers; D020672:I-kappa B Proteins / Q000378:metabolism; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000037:antagonists & inhibitors / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D015675:Osteocalcin / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects; D000076182:Sp7 Transcription Factor; D014157:Transcription Factors / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000008:administration & dosage*
chemical_list: D050659:Core Binding Factor Alpha 1 Subunit; D017931:DNA Primers; D005819:Genetic Markers; D020672:I-kappa B Proteins; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; C493716:Runx2 protein, mouse; D000076182:Sp7 Transcription Factor; C479466:Sp7 protein, mouse; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; D015675:Osteocalcin; D000072000:NF-KappaB Inhibitor alpha; D000469:Alkaline Phosphatase