title: [MAPK-ERK1/2 signaling pathway regulates osteogenic gene expression in rat osteoblasts in vitro].
abstract: OBJECTIVE
  To investigate the effect of inhibition and activation of MAPK-ERK1/2 pathway on the expression of osteogenic genes and proliferation of rat osteoblasts in vitro.
  
  
  METHODS
  Primarily cultured rat osteoblasts, identified by cell morphology studies and ALP staining, were exposed to 1% or 5% rat serum for 24 h or to the specific MAPK-ERK1/2 inhibitor PD0325901. The downstream molecules of MAPK-ERK1/2 pathway including p-ERK1/2 and ERK1/2, osteogenic genes such as Runx2 and Type I collagen, and proliferating cell nuclear antigen (PCNA) were detected by Western Blotting, and alkaline phosphatase activities were analyzed quantitatively.
  
  
  RESULTS
  Compared with 1% rat serum-treated cells, exposure of the cells to a higher concentration (5%) of rat serum caused a significantly increased phosphorylation level of p-ERK1/2 (P<0.05) and obviously enhanced expressions of the osteogenic genes (Runx2, type I collagen and ALP) and PCNA (P<0.05). Inhibition of the MAPK-ERK1/2 pathway with PD0325901 resulted in suppressed expressions of the osteogenic genes and PCNA.
  
  
  CONCLUSIONS
  The activation of MAPK-ERK1/2 pathway promotes the expression of osteogenic genes such as Runx2, type I collagen and ALP and enhances the proliferative activity of the osteoblasts, while inhibition of this pathway suppresses the expressions of these genes and the cell proliferation, suggesting that this pathway may potentially serve as a therapeutic target for osteoporosis.
authors.affiliation: Shi's Center of Orthopedics and Traumatology, Shuguang Hospital Affiliated to Shanghai University of TCM; Institute of Traumatology and Orthopedics, Shanghai Academy of Traditional Chinese Medicine, Shanghai 201203, China. E-mail: 051101049@fudan.edu.cn.
authors.forename: Daofang
authors.initials: D
authors.lastname: Ding
authors.forename: Linghui
authors.initials: L
authors.lastname: Li
authors.forename: Yi
authors.initials: Y
authors.lastname: Song
authors.forename: Guoqing
authors.initials: G
authors.lastname: DU
authors.forename: Xiaoen
authors.initials: X
authors.lastname: Wei
authors.forename: Yuelong
authors.initials: Y
authors.lastname: Cao
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D001549:Benzamides / Q000494:pharmacology*; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D024042:Collagen Type I / Q000378:metabolism; D050659:Core Binding Factor Alpha 1 Subunit / Q000378:metabolism; D004159:Diphenylamine / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D018809:Proliferating Cell Nuclear Antigen / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D024042:Collagen Type I; D050659:Core Binding Factor Alpha 1 Subunit; D018809:Proliferating Cell Nuclear Antigen; C493717:Runx2 protein, rat; C506614:mirdametinib; D004159:Diphenylamine; C535149:Mapk1 protein, rat; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D000469:Alkaline Phosphatase