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J.Health Sci., 49(3), 243-247, 2003
Inhibition of Degranulation of RBL-2H3 Cells by Casein Kinase II Substrate Peptide
Jun-ichi Onose, Reiko Teshima,* Rhosuke Nakamura, and Jun-ichi Sawada
Division of Biochemistry and Immunochemistry, National Institute of Health Sciences, 1-18-1, Kamiyoga, Setagaya-ku, Tokyo 158-8501, Japan
In a previous study, we demonstrated the existence of casein kinase II-like ectokinase activity on rat basophilic leukemia 2H3 (RBL-2H3) cells (Immunol. Let. 68, 369, 1999), and to determine the role of ectokinase in the degranulation of RBL-2H3 cells, in this study we investigated the effect of casein kinase II substrate peptide on the degranulation by the cells. Casein kinase II peptide (RRRDDDSDDD) dose dependently (IC50 = 50 mu M) inhibited beta-hexosaminidase release by IgE-sensitized antigen-stimulated RBL-2H3 cells, whereas casein kinase II peptide analogue (RRRDDDADDD) only partially inhibited beta-hexosaminidase release by antigen-stimulated RBL-2H3 cells. Preincubation of RBL-2H3 cells with 200 mu M of casein kinase II peptide significantly inhibited external 130 kDa protein phosphorylation, and casein kinase II peptide inhibited the sustained increase in cytosolic calcium ion concentration in response to antigen stimulation. Our findings suggest that casein kinase II acts as an ectokinase in RBL-2H3 cells and that casein kinase II peptide acts as a competitor for phosphorylation of ectoprotein, which involves degranulation and a transmembrane influx of Ca2+ by IgE receptor cross-linking. Another casein kinase II inhibitor, GT copolymer, also inhibited the degranulation of antigen-stimulated RBL-2H3 cells. Thus, the modulator of casein kinase II activity seems to be a good tool for the inhibitor of signal transduction in RBL-2H3 cells.
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