Cleavage of RIPK1 by caspase-8 is crucial for limiting apoptosis and necroptosis
Cleavage of RIPK1 by caspase-8 is crucial for limiting apoptosis and necroptosis
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DOI：
10.1038/s41586-019-1548-x
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发表时间：
2019-10-17
期刊：
影响因子：
64.8
通讯作者：
Dixit, Vishva M.
中科院分区：
文献类型：
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作者：
Newton, Kim;Wickliffe, Katherine E.;Dixit, Vishva M.
天冬氨酸特异性半胱氨酸蛋白酶caspase-8抑制RIPK3和MLKL介导的坏死细胞死亡。事实上，缺乏caspase-8的小鼠在胚胎发生过程中以RIPK3-和mlkl依赖的方式死亡（1-3）。在人类中，caspase-8缺乏与免疫缺陷(4)或非常早发的炎症性肠病(5)有关。在体内被caspase-8切割以防止坏死性下垂的底物尚未明确。在这里，我们发现表达催化失活caspase-8（C362A）的敲入小鼠由于mlkl依赖性坏死性死亡而作为胚胎死亡，类似于caspase-8缺陷小鼠。因此，caspase-8必须切割自身、其他蛋白或两者来抑制坏死性坏死。表达caspase-8（D212A/D218A/D225A/D387A）不能自我切割的小鼠是活的，表达c-FLIP或CYLD蛋白的小鼠也是活的，这些蛋白已经突变以阻止caspase-8的切割。相比之下，表达RIPK1（D325A）的小鼠（其中caspase-8切割位点Asp325发生突变）在妊娠中期死亡。胚胎致死性可通过RIPK1失活、TNFR1缺失或MLKL和caspase-8接头FADD缺失来阻止，但不能仅通过MLKL缺失来阻止。因此，RIPK1（D325A）似乎触发TNF、RIPK1和FADD-caspase-8的激酶活性介导的细胞死亡。因此，Ripk1（D325A/D325A）胚胎卵黄囊中含有裂解caspase-3的垂死内皮细胞异常丰富。杂合子Ripk1（D325A/+）细胞和小鼠是有活力的，但也比野生型细胞或小鼠更容易受到tnf诱导的细胞死亡。我们的数据显示，RIPK1的Asp325对于限制响应TNF的异常细胞死亡至关重要，这与caspase-8切割RIPK1是拆除诱导死亡复合物的机制的观点一致。
The aspartate-specific cysteine protease caspase-8 suppresses necroptotic cell death mediated by RIPK3 and MLKL. Indeed, mice that lack caspase-8 die in a RIPK3- and MLKL-dependent manner during embryogenesis(1-3). In humans, caspase-8 deficiency is associated with immunodeficiency(4) or very early onset inflammatory bowel disease(5). The substrates that are cleaved by caspase-8 to prevent necroptosis in vivo have not been defined. Here we show that knock-in mice that express catalytically inactive caspase-8(C362A) die as embryos owing to MLKL-dependent necroptosis, similar to caspase-8-deficient mice. Thus, caspase-8 must cleave itself, other proteins or both to inhibit necroptosis. Mice that express caspase-8(D212A/D218A/D225A/D387A), which cannot cleave itself, were viable, as were mice that express c-FLIP or CYLD proteins that had been mutated to prevent cleavage by caspase-8. By contrast, mice that express RIPK1(D325A), in which the caspase-8 cleavage site Asp325 had been mutated, died midgestation. Embryonic lethality was prevented by inactivation of RIPK1, loss of TNFR1, or loss of both MLKL and the caspase-8 adaptor FADD, but not by loss of MLKL alone. Thus, RIPK1(D325A) appears to trigger cell death mediated by TNF, the kinase activity of RIPK1 and FADD-caspase-8. Accordingly, dying endothelial cells that contain cleaved caspase-3 were abnormally abundant in yolk sacs of Ripk1(D325A/D325A) embryos. Heterozygous Ripk1(D325A/+) cells and mice were viable, but were also more susceptible to TNF-induced cell death than were wild-type cells or mice. Our data show that Asp325 of RIPK1 is essential for limiting aberrant cell death in response to TNF, consistent with the idea that cleavage of RIPK1 by caspase-8 is a mechanism for dismantling death-inducing complexes.