Wajant H, Johannes F J, Haas E, Siemienski K, Schwenzer R, Schubert G, Weiss T, Grell M, Scheurich P
Institute of Cell Biology and Immunology, University of Stuttgart, Allmandring 31, 70569 Stuttgart, Germany.
Curr Biol. 1998 Jan 15;8(2):113-6. doi: 10.1016/s0960-9822(98)70042-9.
Fas/Apo1 and other cytotoxic receptors of the tumor necrosis factor receptor (TNFR) family contain a cytoplasmic death domain (DD) [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] that activates the apoptotic process by interacting with the DD-containing adaptor proteins TNFR-associated DD protein (TRADD) [12] [13] and Fas-associated DD protein (FADD/MORT1) [14] [15], leading to the activation of cysteine proteases of the caspase family [16]. Stimulation of Fas/Apo1 leads to the formation of a receptor-bound death-inducing signaling complex (DISC), consisting of FADD and two different forms of caspase-8 [17] [18] [19]. Transient expression of a dominant-negative mutant of FADD impairs TNFR60-mediated and Fas/Apo1-mediated apoptosis [13] [20], but has no effect on TNF-related apoptosis-inducing ligand (TRAIL/Apo2L)-induced cell death [7] [8] [9] [10] [21]. To study the function of FADD in DD-receptor signaling in more detail, we established HeLa cells that stably expressed a green fluorescent protein (GFP)-tagged dominant-negative mutant of FADD, GFP-DeltaFADD. Interestingly, expression of this mutant inhibited cell death induced by TNFR60, Fas/Apo1 and TRAIL-R/Apo2. In addition, GFP-DeltaFADD did not interfere with TNF-mediated gene induction or with activation of NF-kappaB or Jun N-terminal kinase (JNK), demonstrating that FADD is part of the TNFR60-initiated apoptotic pathway but does not play a role in TNFR60-mediated gene induction. Fas/Apo1-mediated activation of JNK was unaffected by the expression of GFP-DeltaFADD, suggesting that in Fas/Apo1 signaling the apoptotic pathway and the activation of JNK diverge at a level proximal to the receptor, upstream of or parallel to FADD.
Fas/Apo1和肿瘤坏死因子受体（TNFR）家族的其他细胞毒性受体含有一个细胞质死亡结构域（DD）[1][2][3][4][5][6][7][8][9][10][11]，该结构域通过与含DD的衔接蛋白肿瘤坏死因子受体相关DD蛋白（TRADD）[12][13]和Fas相关DD蛋白（FADD/MORT1）[14][15]相互作用来激活凋亡过程，从而导致半胱天冬酶家族的半胱氨酸蛋白酶激活[16]。Fas/Apo1的刺激导致形成一种受体结合的死亡诱导信号复合物（DISC），该复合物由FADD和两种不同形式的半胱天冬酶-8组成[17][18][19]。FADD显性负性突变体的瞬时表达会损害TNFR60介导的和Fas/Apo1介导的凋亡[13][20]，但对肿瘤坏死因子相关凋亡诱导配体（TRAIL/Apo2L）诱导的细胞死亡没有影响[7][8][9][10][21]。为了更详细地研究FADD在DD受体信号传导中的功能，我们建立了稳定表达绿色荧光蛋白（GFP）标记的FADD显性负性突变体GFP-ΔFADD的HeLa细胞。有趣的是，该突变体的表达抑制了TNFR60、Fas/Apo1和TRAIL-R/Apo2诱导的细胞死亡。此外，GFP-ΔFADD不干扰肿瘤坏死因子介导的基因诱导或核因子κB或Jun N末端激酶（JNK）的激活，这表明FADD是TNFR60启动的凋亡途径的一部分，但在TNFR60介导的基因诱导中不起作用。GFP-ΔFADD的表达不影响Fas/Apo1介导的JNK激活，这表明在Fas/Apo1信号传导中，凋亡途径和JNK的激活在受体近端、FADD上游或与FADD平行的水平上发生分歧。
