CTGF/Hcs24 induces chondrocyte differentiation through a p38 mitogen-activated protein kinase (p38MAPK), and proliferation through a p44/42 MAPK/extracellular-signal regulated kinase (ERK).
Connective tissue growth factor/hypertrophic chondrocyte specific gene product 24 (CTGF/Hcs24) promotes proliferation and differentiation of chondrocytes in culture. We investigated the roles of two major types of mitogen activated protein kinase (MAPK) in the promotion of proliferation and differentiation by CTGF/Hcs24. Here we report the effects of the MAPKK/MEK 1/2 inhibitor, PD098059, and p38 MAPK inhibitor, SB203580, in a human chondrosarcoma-derived chondrocytic cell line (HCS-2/8) and rabbit growth cartilage (RGC) cells treated with CTGF/Hcs24. In the proliferation phase, CTGF/Hcs24 induced a approximately fivefold increase in the phosphorylation of p44/42 MAPK/ERK and a approximately twofold increase in that of p38 MAPK in an in vivo kinase assay. These inhibitors of MAPKK and MAPK suppressed phosphorylation of ets-like gene-1 (Elk-1) and nuclear activating transcription factor-2 (Atf-2) induced by CTGF/Hcs24 in a dose-dependent manner, respectively. Western blot analysis showed that phosphorylation of ERK was induced from 30 to 60 min and phosphorylation of p38 MAPK from 10 to 15 min after the addition of CTGF/Hcs24 in confluence HCS-2/8 cells. PD098059 suppressed the DNA synthesis of HCS-2/8 cells and RGC cells, while SB203580 did not. On the other hand, the p38 MAPK inhibitor, SB203580, completely inhibited the CTGF/Hcs24-induced synthesis of proteoglycans in HCS-2/8 cells and RGC cells but the MEK1/2 inhibitor, PD098059, did not. These results suggest that ERK mediates the CTGF/Hcs24-induced proliferation of chondrocytes, and that p38 MAPK mediates the CTGF/Hcs24-induced differentiation of chondrocytes.
Yosimichi
G
G
Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine and Dentistry, Okayama, Japan.
Nakanishi
T
T
Nishida
T
T
Hattori
T
T
Takano-Yamamoto
T
T
Takigawa
M
M
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D019902:Chondrocytes / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism; D055513:Connective Tissue Growth Factor; D004247:DNA / Q000096:biosynthesis; D005419:Flavonoids / Q000494:pharmacology; D017930:Genes, Reporter; D006133:Growth Substances / Q000494:pharmacology*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D017874:Immediate-Early Proteins / Q000494:pharmacology*; D066298:In Vitro Techniques; D036341:Intercellular Signaling Peptides and Proteins; D008156:Luciferases / Q000235:genetics; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011509:Proteoglycans / Q000096:biosynthesis; D011725:Pyridines / Q000494:pharmacology; D011817:Rabbits; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction; D048051:p38 Mitogen-Activated Protein Kinases
C526317:CCN2 protein, human; D005419:Flavonoids; D006133:Growth Substances; D007093:Imidazoles; D017874:Immediate-Early Proteins; D036341:Intercellular Signaling Peptides and Proteins; D011509:Proteoglycans; D011725:Pyridines; D011994:Recombinant Proteins; D055513:Connective Tissue Growth Factor; D004247:DNA; D008156:Luciferases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; C093642:SB 203580; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one