title: Rho-kinase regulates thrombin-stimulated interleukin-6 synthesis via p38 mitogen-activated protein kinase in osteoblasts.
abstract: We have previously reported that thrombin stimulates synthesis of interleukin-6 (IL-6), a potent bone resorptive agent, in osteoblast-like MC3T3-E1 cells. In the present study, we investigated the mechanism of thrombin in the thrombin-stimulated IL-6 synthesis and the involvement of Rho-kinase in MC3T3-E1 cells. Thrombin time-dependently induced the phosphorylation of p44/p42 mitogen-activated protein (MAP) kinase, p38 MAP kinase, stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK) and myosin phosphatase targeting subunit-1 (MYPT-1), a Rho-kinase substrate. While SP600125, an inhibitor of SAPK/JNK, failed to reduce IL-6 synthesis, PD98059, a specific inhibitor of MEK, and SB203580 and BIRB0796, potent inhibitors of p38 MAP kinase, suppressed the IL-6 synthesis induced by thrombin. Y27632, a specific Rho-kinase inhibitor, significantly reduced thrombin-stimulated IL-6 synthesis as well as the MYPT-1 phosphorylation. Fasudil, another inhibitor of Rho-kinase, suppressed thrombin-stimulated IL-6 synthesis. Y27632 and fasudil failed to affect thrombin-induced phosphorylation of p44/p42 MAP kinase. Y27632 as well as fasudil attenuated thrombin-induced phosphorylation of p38 MAP kinase. These results strongly suggest that Rho-kinase regulates thrombin-stimulated IL-6 synthesis via p38 MAP kinase activation in osteoblasts.
authors.affiliation: Department of Orthopedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Kato
authors.forename: Takanobu
authors.initials: T
authors.lastname: Otsuka
authors.forename: Rie
authors.initials: R
authors.lastname: Matsushima-Nishiwaki
authors.forename: Hideo
authors.initials: H
authors.lastname: Natsume
authors.forename: Osamu
authors.initials: O
authors.lastname: Kozawa
authors.forename: Haruhiko
authors.initials: H
authors.lastname: Tokuda
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002460:Cell Line; D004797:Enzyme-Linked Immunosorbent Assay; D015850:Interleukin-6 / Q000096:biosynthesis*; D048670:MAP Kinase Kinase 4 / Q000378:metabolism; D051379:Mice; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D043263:Myosin-Light-Chain Phosphatase; D010006:Osteoblasts / Q000187:drug effects* / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D013917:Thrombin / Q000494:pharmacology*; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*; D054460:rho-Associated Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D015850:Interleukin-6; D054460:rho-Associated Kinases; D009219:Myosin-Light-Chain Kinase; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D043263:Myosin-Light-Chain Phosphatase; C510645:Ppp1r12a protein, mouse; D013917:Thrombin