肿瘤坏死因子α（TNF-α）是一种促炎症细胞因子，能够诱导外在凋亡和坏死程序。肿瘤坏死因子受体相关因子6（TRAF6）是TRAF蛋白家族的一员，是一种E3连接酶，通过激活核因子κB（NFκB）和丝裂原活化蛋白激酶（MAPK）介导炎症信号。尽管TRAF6的功能已经被确定，但其在TNF-α诱导的细胞死亡中的作用仍不清楚。我们报道了TRAF6是TNF-α诱导的细胞死亡的负调节因子，但不影响TNF-α诱导的NFκB激活。TRAF6缺陷加速了TNF-α诱导的凋亡和坏死程序，但这种加速可以通过重构TRAF6或TRAF6C70A来逆转，表明E3连接酶活性对此活性不是必需的。在机制上，TRAF6直接与TNF-α诱导的细胞死亡信号途径中的RIPK1相互作用，这阻止了RIPK1与细胞死亡复合物的成分（如本身、FADD或RIPK3）相互作用，从而抑制了死亡复合物的组装。值得注意的是，IKK是TRAF6与RIPK1相互作用所需的。在体内，Traf6-/-胚胎在肝脏中的细胞死亡水平更高，但同时敲除Tnf可以挽救这种情况。最后，TRAF6敲低异种移植具有高度对坏死程序的敏感性。我们得出结论，在体内和体外，TRAF6和IKK复合物协同抑制细胞死亡复合物的组装，从而抑制TNF-α诱导的细胞死亡。©2023年作者，ADMCAssociazione Differenziamento e Morte Cellulare独家许可。

Tumor necrosis factor α (TNF-α) is a pro-inflammatory cytokine capable of inducing extrinsic apoptosis and necroptosis. Tumor necrosis factor receptor-associated factor 6 (TRAF6), an E3 ligase, is a member of the TRAF family of proteins, which mediates inflammatory signals by activating nuclear factor kappa B (NFкB) and mitogen-activated protein kinase (MAPK). Although the functions of TRAF6 have been identified, its role in TNF-α-induced cell death remains poorly understood. Here, we report that TRAF6 is a negative modulator of TNF-α-induced cell death but does not affect TNF-α-induced NFκB activation. TRAF6 deficiency accelerates both TNF-α-induced apoptosis and necroptosis; however, the acceleration can be reversed by reconstituting TRAF6 or TRAF6C70A, suggesting that E3 ligase activity is not required for this activity. Mechanistically, TRAF6 directly interacts with RIPK1 during TNF-α-induced cell death signaling, which prevents RIPK1 from interacting with components of the cell death complex such as itself, FADD or RIPK3. These processes suppress the assembly of the death complex. Notably, IKK was required for TRAF6 to interact with RIPK1. In vivo, Traf6-/- embryos exhibited higher levels of cell death in the liver but could be rescued by the simultaneous knockout of Tnf. Finally, TRAF6 knockdown xenografts were highly sensitive to necroptotic stimuli. We concluded that TRAF6 suppresses TNF-α-induced cell death in coordination with IKK complexes in vivo and in vitro by suppressing the assembly of cell death complex.© 2023. The Author(s), under exclusive licence to ADMC Associazione Differenziamento e Morte Cellulare.