Matsuyama S, Koide Y, Yoshida T O
Department of Microbiology and Immunology, Hamamatsu University School of Medicine, Japan.
Eur J Immunol. 1993 Dec;23(12):3194-202. doi: 10.1002/eji.1830231223.
Superantigens including staphylococcal enterotoxins (SE) bind to major histocompatibility complex class II molecules and interact with T cells bearing particular V beta chains. SEB was shown to induce the expression of interleukin (IL)-1 beta and tumor necrosis factor (TNF)-alpha genes in human peripheral blood monocytes bearing HLA class II molecules. Monoclonal antibodies directed against HLA-DR and -DQ abolished the SEB-induced expression of both the IL-1 beta and TNF-alpha genes, suggesting that the HLA class II molecules mediated the gene expression. Therefore, we investigated the signal transduction mechanism responsible for the expression of IL-1 beta and TNF-alpha genes induced by binding of SEB to the HLA class II molecules. Three protein tyrosine kinase (PTK) inhibitors, genistein, herbimycin A, and tyrphostin, each of which has a different mechanism of action, strongly inhibited the expression of the monokine mRNA induced by SEB. Analyses of PTK activity revealed that SEB induced a rapid increase of membrane-associated PTK activity and this was blocked by tyrphostin. Furthermore, H-7 inhibited the expression of the monokine mRNA induced by SEB, suggesting the involvement of protein kinase C (PKC) in the signaling pathway. The involvement of PKC was confirmed by the observations that phorbol 12-myristate 13-acetate (PMA), a direct activator of PKC, induced the expression of the monokine mRNA and that SEB evoked the activation of membrane-associated PKC. Both activation of PKC and expression of the monokine mRNA induced by SEB appeared to be inhibited by tyrphostin, but those induced by PMA were not. Taken together, these findings indicate that both PTK and PKC play essential roles in HLA class II molecule-mediated signal transduction elicited by SEB and that PTK activation may precede PKC activation in the signaling pathway.
包括葡萄球菌肠毒素（SE）在内的超抗原可与主要组织相容性复合体II类分子结合，并与携带特定Vβ链的T细胞相互作用。已证明SEB可诱导携带HLA II类分子的人外周血单核细胞中白细胞介素（IL）-1β和肿瘤坏死因子（TNF）-α基因的表达。针对HLA-DR和-DQ的单克隆抗体消除了SEB诱导的IL-1β和TNF-α基因的表达，这表明HLA II类分子介导了基因表达。因此，我们研究了负责SEB与HLA II类分子结合诱导的IL-1β和TNF-α基因表达的信号转导机制。三种蛋白酪氨酸激酶（PTK）抑制剂——染料木黄酮、除莠霉素A和 tyrphostin，它们各自具有不同的作用机制，均强烈抑制了SEB诱导的单核因子mRNA的表达。对PTK活性的分析表明，SEB诱导膜相关PTK活性迅速增加，而这被tyrphostin阻断。此外，H-7抑制了SEB诱导的单核因子mRNA的表达，提示蛋白激酶C（PKC）参与了信号通路。通过观察佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA，PKC的直接激活剂）诱导单核因子mRNA的表达以及SEB引起膜相关PKC的激活，证实了PKC的参与。SEB诱导的PKC激活和单核因子mRNA的表达似乎均被tyrphostin抑制，但PMA诱导的则未被抑制。综上所述，这些发现表明PTK和PKC在SEB引发的HLA II类分子介导的信号转导中均起重要作用，并且在信号通路中PTK激活可能先于PKC激活。
