Journal of Biochemistry Advance Access published online on December 23, 2008
Journal of Biochemistry, doi:10.1093/jb/mvn172
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Blockage by SP600125 of Fc
Receptor-induced degranulation and cytokine gene expression in mast cells is mediated through inhibition of phosphatidylinositol 3-kinase signaling pathway
1Department of Developmental and Regenerative Biology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan
2Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
3Department of Safety Research on Blood and Biological Products, National Institute of Infectious Diseases, Tokyo 208-0011, Japan
4IMBA: Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr. Bohrgasse 3, Vienna A-1030, Austria
*To whom correspondence should be addressed: Hiroshi Nishina Fax: +81 3 5803 5829.E-mail address: nishina.dbio{at}mri.ymd.ac.jp (H. Nishina)
Received November 25, 2008; Accepted December 5, 2008
| Abstract |
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SP600125 is used as a specific inhibitor of c-Jun N-terminal kinase (JNK). We initially aimed to examine physiological roles of JNK in mast cells that play a central role in inflammatory and immediate allergic responses. We found that Fc receptor for IgE (Fc
RI)-induced degranulation (serotonin release) and cytokine gene expression (interleukin (IL)-6, tumor necrosis factor-
, and IL-13) in bone marrow-derived mast cells, were almost completely inhibited by SP600125. However, the time course of Fc
RI-induced JNK activation did not correlate with that of serotonin release. Furthermore, Fc
RI-induced degranulation and cytokine gene expression were not impaired in a JNK activator, MKK7-deficient mast cells, in which JNK activation was lost. These results indicate that the inhibitory effects by SP600125 are not due to impaired JNK activation. Instead, we found that SP600125 markedly inhibited the Fc
RI-induced activation of phosphatidylinositol 3-kinase (PI3K) and Akt, the same as a PI3K inhibitor, wortmannin. Finally, we found that SP600125 specifically inhibits delta form of p110 catalytic subunit (p110
) of PI3K. Thus, SP600125 exerts its influence on mast cell functions by inhibiting the kinase activity of PI3KIbut not JNK.
Key Words: SP600125, mast cell, IgE, JNK, PI3K
Mailing Address: Hiroshi Nishina, Ph.D., Department of Developmental and Regenerative Biology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan