1] Inflammation Research Center, Molecular Signaling and Cell Death Unit, VIB, Ghent, Belgium [2] Department of Biomedical Molecular Biology, Molecular Signaling and Cell Death Unit, Ghent University, Ghent, Belgium.
Center for Molecular Medicine, Laboratory for Neurobiology and Gene Therapy, Katholieke Universiteit Leuven, Leuven, Belgium.
Cell Death Dis. 2014 Jan 16;5(1):e1004. doi: 10.1038/cddis.2013.531.
In human cells, the RIPK1-RIPK3-MLKL-PGAM5-Drp1 axis drives tumor necrosis factor (TNF)-induced necroptosis through mitochondrial fission, but whether this pathway is conserved among mammals is not known. To answer this question, we analyzed the presence and functionality of the reported necroptotic axis in mice. As in humans, knockdown of receptor-interacting kinase-3 (RIPK3) or mixed lineage kinase domain like (MLKL) blocks TNF-induced necroptosis in L929 fibrosarcoma cells. However, repression of either of these proteins did not protect the cells from death, but instead induced a switch from TNF-induced necroptosis to receptor-interacting kinase-1 (RIPK1) kinase-dependent apoptosis. In addition, although mitochondrial fission also occurs during TNF-induced necroptosis in L929 cells, we found that knockdown of phosphoglycerate mutase 5 (PGAM5) and dynamin 1 like protein (Drp1) did not markedly protect the cells from TNF-induced necroptosis. Depletion of Pink1, a reported interactor of both PGAM5 and Drp1, did not affect TNF-induced necroptosis. These results indicate that in these murine cells mitochondrial fission and Pink1 dependent processes, including Pink-Parkin dependent mitophagy, apparently do not promote necroptosis. Our data demonstrate that the core components of the necrosome (RIPK1, RIPK3 and MLKL) are crucial to induce TNF-dependent necroptosis both in human and in mouse cells, but the associated mechanisms may differ between the two species or cell types.
在人类细胞中，RIPK1-RIPK3-MLKL-PGAM5-Drp1 轴通过线粒体裂变驱动肿瘤坏死因子 (TNF) 诱导的坏死性凋亡，但该途径是否在哺乳动物中保守尚不清楚。为了回答这个问题，我们分析了报道的坏死性凋亡轴在小鼠中的存在和功能。与人一样，敲低受体相互作用激酶 3 (RIPK3) 或混合谱系激酶结构域样 (MLKL) 可阻断 L929 纤维肉瘤细胞中 TNF 诱导的坏死性凋亡。然而，抑制这些蛋白中的任何一种都不能保护细胞免受死亡，反而会诱导从 TNF 诱导的坏死性凋亡到受体相互作用激酶 1 (RIPK1) 激酶依赖性细胞凋亡的转换。此外，尽管在线粒体裂变也发生在 L929 细胞中 TNF 诱导的坏死性凋亡期间，我们发现敲低磷酸甘油酸变位酶 5 (PGAM5) 和 dynamin 1 样蛋白 (Drp1) 并不能显著保护细胞免受 TNF 诱导的坏死性凋亡。报道称 PGAM5 和 Drp1 的相互作用蛋白 Pink1 的耗竭并不影响 TNF 诱导的坏死性凋亡。这些结果表明，在这些鼠细胞中线粒体裂变和 Pink1 依赖性过程，包括 Pink-Parkin 依赖性线粒体自噬，显然不会促进坏死性凋亡。我们的数据表明，坏死体的核心成分（RIPK1、RIPK3 和 MLKL）对于在人和鼠细胞中诱导 TNF 依赖性坏死性凋亡都是至关重要的，但这两种物种或细胞类型之间的相关机制可能不同。
