PKC ZETA IS A MOLECULAR SWITCH IN SIGNAL-TRANSDUCTION OF TNF-ALPHA, BIFUNCTIONALLY REGULATED BY CERAMIDE AND ARACHIDONIC-ACID
PKC ZETA IS A MOLECULAR SWITCH IN SIGNAL-TRANSDUCTION OF TNF-ALPHA, BIFUNCTIONALLY REGULATED BY CERAMIDE AND ARACHIDONIC-ACID
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DOI：
10.1002/j.1460-2075.1995.tb07188.x
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发表时间：
1995-05-01
期刊：
影响因子：
11.4
通讯作者：
PFIZENMAIER, K
中科院分区：
文献类型：
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作者：
MULLER, G;AYOUB, M;PFIZENMAIER, K
肿瘤坏死因子（tnf - α）刺激磷脂酶产生脂质第二信使的许多信号转导途径。然而，这些信使的直接分子靶标，特别是神经酰胺和花生四烯酸（AA）及其在TNF信号传导中的作用尚不清楚。在这项研究中，我们研究了神经酰胺和AA在调节PKC非典型同工酶PKC zeta中的关系。对NF κ B活化的tnf - α处理的U937细胞表现出PKC zeta磷酸化增强，刺激后30秒就可以检测到，[C-14]神经酰胺特异性结合并以双相方式调节PKC zeta激酶活性。结合研究表明，高亲和力和低亲和力结合的b（max）值分别为60和600 nM， K-d值分别为7.5和320 nM。当神经酰胺浓度低至0.5 nM时，自磷酸化水平可增加4倍，而当神经酰胺浓度为60 nM时，自磷酸化水平再次下降至基础水平。有趣的是，AA竞争神经酰胺结合并抑制基础和神经酰胺刺激的PKC zeta激酶活性
Tumor necrosis factor (TNF-alpha) stimulates a number of signal transduction pathways in which phospholipases produce lipid second messengers. However, the immediate molecular targets of these messengers, in particular those of ceramide and arachidonic acid (AA) and their role in TNF signaling are not well defined. In this study we investigated the relationship of ceramide and AA in regulating an atypical PKC isozyme, PKC zeta. U937 cells responding to TNF-alpha treatment with NF kappa B activation displayed enhanced phosphorylation of PKC zeta, which is already detectable 30 s after stimulation, [C-14]ceramide specifically binds to and regulates kinase activity of PKC zeta in a biphasic manner. Binding studies indicate high and low affinity binding with b(max) values of 60 and 600 nM and K-d values of 7.5 and 320 nM respectively. At ceramide concentrations as low as 0.5 nM an up to 4-fold increase in autophosphorylation is obtained, which, at concentrations >60 nM, again declines to basal levels. Interestingly, AA competes for ceramide binding and inhibits basal and ceramide-stimulated PKC zeta kinase activity at