p38 mitogen-activated protein kinase functionally contributes to chondrogenesis induced by growth/differentiation factor-5 in ATDC5 cells.
Recent studies of intracellular signal transduction mechanisms for the transforming growth factor-beta (TGF-beta) superfamily have focused on Smad proteins, but have paid little attention to mitogen-activated protein (MAP) kinase cascades. Here we demonstrate that growth/differentiation factor-5 (GDF-5), but neither bone morphogenetic protein-2 (BMP-2) nor TGF-beta1, fully promotes the early phase of the chondrogenic response by inducing cellular condensation followed by cartilage nodule formation in a mouse chondrogenic cell line, ATDC5. We investigated which, if any, of the three major types of MAP kinase plays a functional role in the promotion of chondrogenesis induced by GDF-5. GDF-5 induced phosphorylation of p38 MAP kinase and extracellular signal-regulated kinase (ERK) but not that of c-Jun N-terminal kinase (JNK). The phosphorylation of p38 MAP kinase was also induced by BMP-2 and TGF-beta1. An inhibitor of p38 and p38 beta MAP kinase, SB202190, showed complete inhibition of cartilage nodule formation but failed to affect alkaline phosphatase (ALP) activity induced by GDF-5. Expression of the type II collagen gene, a hallmark of chondrogenesis in vertebrates, was also induced by GDF-5 treatment and strongly suppressed by SB202190. On the other hand, although an inhibitor of MAP/ERK kinase, PD98059, inhibited the rapid phosphorylation of ERK by GDF-5, it inhibited neither ALP activity nor cartilage nodule formation induced by GDF-5. These results strongly suggest that the p38 MAP kinase cascade is involved in GDF-5 signaling pathways and that a role of the p38 MAP kinase pathway is necessary over a longer period to promote chondrogenesis in ATDC5 cells.
Discovery Research Laboratories, Hoechst Marion Roussel Ltd., 3-2, Minamidai 1-chome, Kawagoe, Saitama, 350-1165, Japan.
K
K
Nakamura
T
T
Shirai
S
S
Morishita
S
S
Uchida
K
K
Saeki-Miura
F
F
Makishima
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D018236:Carcinoma, Embryonal; D002356:Cartilage / Q000187:drug effects / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects; D048429:Cell Size / Q000187:drug effects; D020219:Chondrogenesis / Q000187:drug effects*; D003094:Collagen / Q000235:genetics; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction / Q000187:drug effects; D055428:Growth Differentiation Factor 5; D006133:Growth Substances / Q000494:pharmacology*; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases; D020928:Mitogen-Activated Protein Kinases; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D048051:p38 Mitogen-Activated Protein Kinases
C525718:BMP2 protein, human; C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; C525893:GDF5 protein, human; C525894:Gdf5 protein, mouse; D055428:Growth Differentiation Factor 5; D006133:Growth Substances; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D003094:Collagen; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1; C482125:MAP2K1 protein, human; C482127:Map2k1 protein, mouse; D020929:Mitogen-Activated Protein Kinase Kinases; D000469:Alkaline Phosphatase