Activation of mitogen-activated protein kinase cascades is involved in regulation of bone morphogenetic protein-2-induced osteoblast differentiation in pluripotent C2C12 cells.
Bone morphogenetic protein (BMP)-2, a member of the transforming growth factor-beta (TGF-beta) superfamily, is able to induce osteoblastic differentiation of C2C12 cells. Both Smad and mitogen-activated protein kinase (MAPK) pathways are essential components of the TGF-beta superfamily signaling machinery. Although Smads have been demonstrated to participate in the BMP-2-induced osteoblastic differentiation of C2C12 cells, the role of MAPK has not been addressed. This report shows that BMP-2 activates ERK and p38, but not JNK, in C2C12 cells. Pretreatment of cells with the p38 inhibitor, SB203580, dramatically reduced BMP-2-induced expression of the osteoblast markers alkaline phosphatase (ALP) and osteocalcin (OC). Nevertheless, overexpression of MKK3, a protein kinase that phosphorylates and activates p38, failed to induce ALP or OC expression in the absence of BMP-2, indicating that p38 activation is necessary but not sufficient for the acquisition of the osteoblast phenotype by these cells. Although ALP induction was increased slightly in the presence of PD-98059, a selective inhibitor of the ERK cascade, this compound significantly inhibited both steady-state and BMP-2-induced OC RNA levels. Our results indicate that p38 and ERK cascades play a crucial role in the osteoblast differentiation of C2C12 cells mediated by BMP-2.
Gallea
S
S
Bone Diseases Group, Hoechst-Marion-Roussel, 111 route de Noisy, 93230 Romainville, France.
Lallemand
F
F
Atfi
A
A
Rawadi
G
G
Ramez
V
V
Spinella-Jaegle
S
S
Kawai
S
S
Faucheu
C
C
Huet
L
L
Baron
R
R
Roman-Roman
S
S
D000469:Alkaline Phosphatase / Q000235:genetics; D000818:Animals; D001846:Bone Development / Q000187:drug effects* / Q000502:physiology; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000378:metabolism / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects* / Q000502:physiology; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D006224:Cricetinae; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D005419:Flavonoids; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology; D007093:Imidazoles / Q000494:pharmacology; D048371:MAP Kinase Kinase 3; D020935:MAP Kinase Signaling System / Q000187:drug effects* / Q000502:physiology; D051379:Mice; D048055:Mitogen-Activated Protein Kinase 8; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics; D020928:Mitogen-Activated Protein Kinases / Q000187:drug effects / Q000378:metabolism; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D015675:Osteocalcin / Q000235:genetics; D011505:Protein-Tyrosine Kinases / Q000235:genetics; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D016212:Transforming Growth Factor beta; D048051:p38 Mitogen-Activated Protein Kinases
C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; D004791:Enzyme Inhibitors; D005419:Flavonoids; D007093:Imidazoles; D011725:Pyridines; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D015675:Osteocalcin; D011505:Protein-Tyrosine Kinases; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048371:MAP Kinase Kinase 3; C482531:Map2k3 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases; D000469:Alkaline Phosphatase; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one