title: 8-Prenylkaempferol accelerates osteoblast maturation through bone morphogenetic protein-2/p38 pathway to activate Runx2 transcription.
abstract: OBJECTIVE
  In this study, we investigated the effect of 8-prenylkaempferol (8-PK), a prenyl-flavonoid isolated from Sophora flavescens, on osteoblast differentiation and maturation.
  
  
  METHODS
  MC3T3-E1 cells were exposed to 8-PK and the cytotoxicity was assayed. Osteoblast differentiation and maturation were evaluated by analyzing alkaline phosphatase (ALP) activity and cell mineralization, respectively. RT-PCR and Western blot were executed to determine the effects of 8-PK on osteoblast differentiation-related gene expression and signaling pathway.
  
  
  RESULTS
  8-PK significantly promoted ALP activity, up-regulated mRNA expressions of osteocalcin, osteopontin, and type I collagen, and induced bone nodules formation. Induction of differentiation by 8-PK was associated with increased bone morphogenetic protein (BMP)-2 expression, and sequentially up-regulated the phosphorylations of Smad1/5/8 and p38, and increased the nuclear translocation of runt-related transcription factor 2 (Runx2). Addition of BMP-2 antagonist noggin blocked 8-PK and recombinant mouse BMP-2-induced ALP activity, reconfirming that BMP-2 production is required in 8-PK-mediated osteoblast differentiation. Noggin also abrogated 8-PK evoked phosphorylations of Smad1/5/8 and p38, suggesting that BMP-2 signaling is required for p38 activation in 8-PK-treated cells. Application of p38 inhibitor SB203580 repressed not only 8-PK-mediated activation of ALP, but also the nuclear translocation of Runx2 and bone nodules formation.
  
  
  CONCLUSIONS
  The present results suggested that BMP-2/p38/Runx2 pathways were involved in 8-PK-induced differentiation/maturation of MC3T3-E1 osteoblasts and firstly demonstrated that 8-PK might be a promising agent for inducing osteogenesis.
authors.affiliation: National Research Institute of Chinese Medicine, Taipei, Taiwan. wfchiou@nricm.edu.tw
authors.forename: Wen-Fei
authors.initials: WF
authors.lastname: Chiou
authors.forename: Chia-Hsin
authors.initials: CH
authors.lastname: Lee
authors.forename: Jyh-Fei
authors.initials: JF
authors.lastname: Liao
authors.forename: Chien-Chih
authors.initials: CC
authors.lastname: Chen
mesh_terms: D000469:Alkaline Phosphatase / Q000502:physiology; D000818:Animals; D015153:Blotting, Western; D055396:Bone Morphogenetic Protein 2 / Q000819:agonists* / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D024042:Collagen Type I / Q000502:physiology; D050659:Core Binding Factor Alpha 1 Subunit / Q000096:biosynthesis*; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology; D044949:Kaempferols / Q000494:pharmacology*; D051379:Mice; D010006:Osteoblasts / Q000187:drug effects* / Q000502:physiology; D015675:Osteocalcin / Q000502:physiology; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology; D053495:Osteopontin / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D015854:Up-Regulation / Q000187:drug effects; D048051:p38 Mitogen-Activated Protein Kinases / Q000187:drug effects* / Q000502:physiology
chemical_list: C532177:8-prenylkaempferol; C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2; D024042:Collagen Type I; D050659:Core Binding Factor Alpha 1 Subunit; D044949:Kaempferols; C493716:Runx2 protein, mouse; D015675:Osteocalcin; D053495:Osteopontin; D048051:p38 Mitogen-Activated Protein Kinases; D000469:Alkaline Phosphatase