Lack of a role for Jun kinase and AP-1 in Fas-induced apoptosis
Lack of a role for Jun kinase and AP-1 in Fas-induced apoptosis
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DOI：
10.1128/mcb.17.1.170
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发表时间：
1997-01-01
影响因子：
5.3
通讯作者：
Ashwell, JD
中科院分区：
文献类型：
--
作者：
Lenczowski, JM;Dominguez, L;Ashwell, JD
Fas（CD 95）的交联诱导细胞凋亡，据报道这种反应依赖于Ras激活途径。自从人类？据报道，细胞凋亡的例子涉及AP-1和/或AP-1激活酶Jun激酶（JNK），Pas或Ras样小GTP结合蛋白的下游效应物，我们评估了这些分子在Fas介导的细胞凋亡中的作用。尽管Pas和Jurkat T细胞的交联确实导致JNK活化，但相对较晚地观察到活性增加，仅在刺激60分钟后才可检测到。阻断Pas介导的JNK活性诱导的SEK 1的显性负性形式的表达对Pas介导的细胞凋亡没有影响。此外，如果细胞凋亡被半胱氨酸蛋白酶抑制剂阻断，则最大有效浓度的抗Pas不会引起JNK活化，这表明在这些条件下，JNK的活化可能继发于细胞凋亡的应激，而不是Fas接合的直接结果。尽管JNK被激活，但通过凝胶位移测定或AP-1应答性报道基因的诱导确定，没有AP-1活性的诱导。用用显性阴性cJun TAM-67稳定转染的Jurkat细胞进一步证实了在PAS介导的死亡中不需要AP-1诱导。虽然TAM-67有效地阻止了白细胞介素-2和cJun基因的AP-1依赖性转录，但它对Pas诱导的细胞死亡没有影响，即使在限制水平的Pas信号传导下也是如此。因此，通过以足以引起细胞死亡的水平连接Pas来诱导Jurkat细胞中的JNK活性可能是凋亡反应的结果，而不是原因。并且AP-1功能对于PAS诱导的细胞凋亡不是必需的。
Cross-linking of Fas (CD95) induces apoptosis, a response that has been reported to depend upon the Ras activation pathway. Since man?; examples of apoptosis have been reported to involve AP-1 and/or the AP-1-activating enzyme Jun kinase (JNK), downstream effecters of Pas or Ras-like small GTP-binding proteins, we evaluated the role of these molecules in Fas-mediated apoptosis. Although cross-linking of Pas an Jurkat T cells did result in JNK activation, increased activity was observed relatively late, being detectable only after 60 min of stimulation. Expression of a dominant negative form of SEK1 that blocked Pas-mediated induction of JNK activity had no effect on Pas-mediated apoptosis, Furthermore, maximally effective concentrations of anti-Pas did not cause JNK activation if apoptosis was blocked by a cysteine protease inhibitor, suggesting that under these conditions, activation of JNK may be secondary to the stress of apoptosis rather than a direct result of Fas engagement, Despite the activation of JNK, there was no induction of AP-I activity as determined by gel shift assay or induction of an AP-1-responsive reporter, The lack of a requirement for AP-1 induction in Pas-mediated death was further substantiated with Jurkat cells that were stably transfected with a dominant negative cJun, TAM-67. While TAM-67 effectively prevented AP-1-dependent transcription of both the interleukin-2 and cJun genes, it had no effect on Pas-induced cell death, even at limiting levels of Pas signaling, Thus, induction of JNK activity in Jurkat cells hy ligation of Pas at levels sufficient to cause cell death is likely a result, rather than a cause, of the apoptotic response, and AP-1 function is not required for Pas-induced apoptosis.