Mühlenbeck F, Haas E, Schwenzer R, Schubert G, Grell M, Smith C, Scheurich P, Wajant H
Institute of Cell Biology and Immunology, University of Stuttgart, Allmandring 31, 70569 Stuttgart, Germany.
J Biol Chem. 1998 Dec 4;273(49):33091-8. doi: 10.1074/jbc.273.49.33091.
In this study we show that TRAIL (tumor necrosis factor-related apoptosis-inducing ligand), also called Apo2L, activates the c-Jun N-terminal kinase (JNK). Interestingly, TRAIL-induced JNK activation occurs in a cell type-specific manner. In HeLa cells, TRAIL-induced JNK activation can be completely blocked with the cysteine protease inhibitor zVAD-fmk, whereas the same inhibitor has no, or even a stimulatory, effect on JNK activation in Kym-1 cells. Hence, TRAIL can engage at least two independent pathways leading to JNK activation, one that is cysteine protease-dependent and one that is cysteine protease-independent. To investigate whether the cysteine protease-dependent signaling of TRAIL leading to JNK activation is related to the apoptotic pathway engaged by this ligand, we investigated HeLa cells stably overexpressing a dominant negative mutant of FADD (Fas-associating protein with death domain) (GFP(green fluorescent protein)DeltaFADD). In these cells, TRAIL-induced cell death and activation of the apoptosis executioner caspase-8 (FLICE/MACH) and caspase-3 (YAMA, CPP-32, Apopain), that belong to caspase subfamily of cysteine proteases, were abrogated, whereas JNK activation remained unaffected and was still sensitive toward z-VAD-fmk. Similar data were found in HeLa cells overexpressing Apo1/Fas and GFPDeltaFADD upon stimulation with agonistic antibodies. These data suggest that cross-linking of the TRAIL receptors and Apo1/Fas, respectively, engages a FADD-dependent pathway leading to the activation of apoptotic caspases and, in parallel, a FADD-independent pathway leading to the stimulation of one or more cysteine proteases capable to activate JNK but not sufficient for the induction of cell death.
在本研究中，我们发现肿瘤坏死因子相关凋亡诱导配体（TRAIL），也称为Apo2L，可激活c-Jun氨基末端激酶（JNK）。有趣的是，TRAIL诱导的JNK激活以细胞类型特异性方式发生。在HeLa细胞中，TRAIL诱导的JNK激活可被半胱氨酸蛋白酶抑制剂zVAD-fmk完全阻断，而相同的抑制剂对Kym-1细胞中的JNK激活没有影响，甚至具有刺激作用。因此，TRAIL可参与至少两条导致JNK激活的独立途径，一条是半胱氨酸蛋白酶依赖性途径，另一条是半胱氨酸蛋白酶非依赖性途径。为了研究TRAIL导致JNK激活的半胱氨酸蛋白酶依赖性信号传导是否与该配体参与的凋亡途径相关，我们研究了稳定过表达FADD（死亡结构域相关的Fas结合蛋白）显性负突变体（绿色荧光蛋白（GFP）ΔFADD）的HeLa细胞。在这些细胞中，TRAIL诱导的细胞死亡以及属于半胱氨酸蛋白酶caspase亚家族的凋亡执行蛋白酶caspase-8（FLICE/MACH）和caspase-3（YAMA、CPP-32、Apopain）的激活被消除，而JNK激活不受影响且仍然对z-VAD-fmk敏感。在用激动性抗体刺激后，在过表达Apo1/Fas和GFPΔFADD的HeLa细胞中也发现了类似的数据。这些数据表明，TRAIL受体和Apo1/Fas的交联分别参与了一条导致凋亡caspase激活的FADD依赖性途径，同时还参与了一条FADD非依赖性途径，该途径导致一种或多种能够激活JNK但不足以诱导细胞死亡的半胱氨酸蛋白酶的刺激。
