title: Ugonin K promotes osteoblastic differentiation and mineralization by activation of p38 MAPK- and ERK-mediated expression of Runx2 and osterix.
abstract: Ugonin K is a flavonoid isolated from the roots of Helminthostachys zeylanica, a folk medicine used to strengthen bone mass and cure bone fracture. It is of interest to determine whether ugonin K has beneficial effect on osteoblast maturation. In this study, MC3T3-E1 osteoblasts were treated with ugonin K. Cell differentiation and mineralization were identified by alkaline phosphatase (ALP) activity and Alizarin red S staining, respectively. RT-PCR and Western blot were used to analyze osteoblast-associated gene expression and signaling pathways. Our results showed that ugonin K significantly induced the increase of ALP activity, expressions of bone sialoprotein (BSP) and osteocalcin (OCN), and mineralization. The mRNA expressions of the transcription factors Runx2 and osterix were also up-regulated by ugonin K. Ugonin K increased the phosphorylated level of p38 and ERK, respectively. In the presence of SB203580, ugonin K induced expressions of Runx2 and osterix, ALP activity, BSP level and bone nodule formation were all completely inhibited, but ugonin K induced OCN expression was not affected. On the other hand, ugonin K-induced ALP activity and mineralization were mildly attenuated by PD98059, but the over-expressed Runx2, osterix, BSP and OCN also were significantly repressed by PD98059. These suggested that both p38 and ERK participate in regulating ugonin K evoked osteogenesis but p38 seemed to play a more important role. Take together, the potential anabolic effect of ugonin K on bone might act through activations of p38- and ERK-mediated Runx2 and osterix expressions to induce the synthesis of osteoids and formation of bone nodule.
authors.affiliation: Department of Pharmacology, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Chia-Hsin
authors.initials: CH
authors.lastname: Lee
authors.forename: Yu-Ling
authors.initials: YL
authors.lastname: Huang
authors.forename: Jyh-Fei
authors.initials: JF
authors.lastname: Liao
authors.forename: Wen-Fei
authors.initials: WF
authors.lastname: Chiou
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001857:Bone Matrix / Q000187:drug effects / Q000378:metabolism; D002113:Calcification, Physiologic / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects*; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics; D004789:Enzyme Activation / Q000187:drug effects; D005419:Flavonoids / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D000076182:Sp7 Transcription Factor; D014157:Transcription Factors / Q000235:genetics*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
chemical_list: D050659:Core Binding Factor Alpha 1 Subunit; D005419:Flavonoids; D012333:RNA, Messenger; D000076182:Sp7 Transcription Factor; C479466:Sp7 protein, mouse; D014157:Transcription Factors; C540912:ugonin K; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D002118:Calcium