Abstract
We screened the small molecule compounds that stimulate osteogenesis by themselves or promote bone morphogenetic protein (BMP)-induced bone formation. We found that a specific inhibitor for MAPK/extracellular signal-regulated kinase kinase (MEK)-1, promoted the early osteoblastic differentiation and mineralization of extracellular matrix (ECM) in C2Cl2 pluripotent mesenchymal cells treated with recombinant human BMP-2 (rhBMP-2) and MC3T3-E1 preosteoblastic cells. ALP activity was synergistically increased by the treatment with a specific MEK-1 inhibitor PD98059 and rhBMP-2 in both cell lines. Twenty-five micromolar PD98059 promoted mineralization of ECM in rhBMP-2-treated C2Cl2 cells and MC3T3-E1 cells. In contrast, PD98059 reduced osteocalcin (OCN) secretion and its transcriptional level in rhBMP-2-treated C2Cl2 cells but increased its secretion and mRNA level in MC3T3-E1 cells. Stable expression of a dominant-negative MEK-1 mutant in C2Cl2 cells represented high ALP activity and low osteocalcin production in the presence of rhBMP-2, while a constitutively active mutant of MEK-1 attenuated both of them. Together, our results indicated that BMP-2-induced mineralization of ECM of pluripotent mesenchymal stem cells and preosteoblastic cells could be controlled by a fine tuning of the MAPK signaling pathway. Further, MEK-1 inhibitors would be useful for the promotion of bone formation, for instance, the treatments for delayed fracture healing or advance of localized osteoporotic change after fracture healing.
Publication types
-
Research Support, Non-U.S. Gov't
MeSH terms
-
Animals
-
Bone Morphogenetic Protein 2
-
Bone Morphogenetic Proteins / pharmacology*
-
Cell Differentiation / drug effects
-
Cell Line / drug effects
-
Cell Line / metabolism
-
Enzyme Induction / drug effects
-
Enzyme Inhibitors / pharmacology*
-
Extracellular Matrix / drug effects*
-
Extracellular Matrix / metabolism
-
Flavonoids / pharmacology*
-
Genes, Dominant
-
Humans
-
MAP Kinase Kinase 1
-
MAP Kinase Signaling System / drug effects
-
MAP Kinase Signaling System / physiology*
-
Mesoderm / cytology
-
Mice
-
Minerals / metabolism*
-
Mitogen-Activated Protein Kinase Kinases / antagonists & inhibitors*
-
Mitogen-Activated Protein Kinase Kinases / physiology
-
Mitogen-Activated Protein Kinases / antagonists & inhibitors*
-
Mitogen-Activated Protein Kinases / physiology
-
Osteoblasts / cytology
-
Osteoblasts / drug effects*
-
Osteoblasts / metabolism
-
Osteocalcin / biosynthesis
-
Osteocalcin / drug effects
-
Osteocalcin / metabolism
-
Pluripotent Stem Cells / cytology
-
Pluripotent Stem Cells / drug effects*
-
Protein Serine-Threonine Kinases / antagonists & inhibitors*
-
Protein Serine-Threonine Kinases / physiology
-
RNA, Messenger / biosynthesis
-
RNA, Messenger / genetics
-
Rats
-
Recombinant Fusion Proteins / pharmacology
-
Recombinant Fusion Proteins / physiology
-
Recombinant Proteins
-
Transcription, Genetic / drug effects
-
Transforming Growth Factor beta*
-
p38 Mitogen-Activated Protein Kinases
Substances
-
BMP2 protein, human
-
Bmp2 protein, mouse
-
Bmp2 protein, rat
-
Bone Morphogenetic Protein 2
-
Bone Morphogenetic Proteins
-
Enzyme Inhibitors
-
Flavonoids
-
Minerals
-
RNA, Messenger
-
Recombinant Fusion Proteins
-
Recombinant Proteins
-
Transforming Growth Factor beta
-
recombinant human bone morphogenetic protein-2
-
Osteocalcin
-
Protein Serine-Threonine Kinases
-
Mitogen-Activated Protein Kinases
-
p38 Mitogen-Activated Protein Kinases
-
MAP Kinase Kinase 1
-
MAP2K1 protein, human
-
Map2k1 protein, mouse
-
Mitogen-Activated Protein Kinase Kinases
-
2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one