HOME HELP CONTACT US SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Takai, S Articles by Kozawa, O PubMed PubMed Citation Articles by Takai, S Articles by Kozawa, O

¹ Department of Pharmacology, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan² Department of Clinical Laboratory, National Center for Geriatrics and Gerontology, National Hospital for Geriatric Medicine, Obu 474-8511, Japan³ Department of Orthopedic Surgery, Nagoya City University Graduate School of Medical Sciences, Nagoya 467-8601, Japan

(Correspondence should be addressed to O Kozawa; Email: okozawa{at}gifu-u.ac.jp)

We have previously reported that protein kinase C negatively regulates basic fibroblast growth factor (FGF-2)-stimulated synthesis of interleukin-6 (IL-6), a potent bone resorptive agent, in osteoblast-like MC3T3-E1 cells. To further clarify the mechanism underlying the synthesis of IL-6 in osteoblasts, we investigated whether p70 S6 kinase is involved in the FGF-2-stimulated IL-6 synthesis in these cells. Rapamycin, an inhibitor of p70 S6 kinase, significantly enhanced the FGF-2-stimulated IL-6 synthesis in a dose-dependent manner. Downregulation of p70 S6 kinase by siRNA markedly amplified the FGF-2-stimulated IL-6 synthesis. 12-O-Tetradecanoylphorbol-13-acetate (TPA), a direct activator of protein kinase C, induced the phosphorylation of p70 S6 kinase. Go6976 and bisindolylmaleimide I, inhibitors of protein kinase C, suppressed the TPA-stimulated phosphorylation of p70 S6 kinase. Additionally, protein kinase C inhibitors markedly reduced the phosphorylation of p70 S6 kinase induced by FGF-2. These results strongly suggest that p70 S6 kinase functions at a point downstream of protein kinase C and limits the FGF-2-stimulated IL-6 synthesis in osteoblasts.