Critical role of protein kinase C betaII in activation of mast cells by monomeric IgE.
Accumulating evidence suggests that IgE-mediated activation of mast cells occurs even in the absence of antigen, which is referred to as "monomeric IgE" responses. Although monomeric IgE was found to induce a wide variety of responses, such as up-regulation of the FcepsilonRI, survival, cytokine production, histamine synthesis, and adhesion to fibronectin, it remains to be clarified how mast cells are activated in the absence of antigen. It has been controversial whether monomeric IgE responses are mediated by a similar signaling mechanism to antigen stimulation, although recent studies suggest that IgE can induce the FcepsilonRI aggregation even in the absence of antigen. In this study, we focused on the role of conventional protein kinase C (cPKC), since this response is suppressed by a specific inhibitor for cPKC. Monomeric IgE-induced Ca(2+) influx was not observed in a mouse mastocytoma cell line, which lacks the expression of PKCbetaII, although Ca(2+) influx induced by cross-linking of the FcepsilonRI was intact. Transfection of PKCbetaII cDNA was found to restore the Ca(2+) influx induced by monomeric IgE in this cell line. Furthermore, the dominant negative form of PKCbetaII (PKCbetaII/T500V) significantly suppressed the Ca(2+) influx, histamine synthesis, and interleukin-6 production in another mouse mast cell line, which is highly sensitive to monomeric IgE. Expression of PKCbetaII/T500V was found not to affect the antigen-induced responses. These results suggest that PKCbetaII plays a critical role in monomeric IgE responses, but not in antigen responses.
Liu
Ying
Y
Department of Physiological Chemistry, Graduate School of Pharmaceutical Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
Furuta
Kazuyuki
K
Teshima
Reiko
R
Shirata
Naritoshi
N
Sugimoto
Yukihiko
Y
Ichikawa
Atsushi
A
Tanaka
Satoshi
S
D000818:Animals; D001483:Base Sequence; D020013:Calcium Signaling; D002460:Cell Line; D018076:DNA, Complementary / Q000235:genetics; D006632:Histamine / Q000096:biosynthesis; D007073:Immunoglobulin E / Q000378:metabolism*; D015850:Interleukin-6 / Q000096:biosynthesis; D008407:Mast Cells / Q000201:enzymology* / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D011493:Protein Kinase C / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D064546:Protein Kinase C beta; D034622:RNA Interference; D017455:Receptors, IgE / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D018076:DNA, Complementary; D015850:Interleukin-6; D017455:Receptors, IgE; D011994:Recombinant Proteins; D007073:Immunoglobulin E; D006632:Histamine; D011493:Protein Kinase C; D064546:Protein Kinase C beta