Necroptosis induction in vitro often requires caspase-8 (Casp8) inhibition by zVAD because pro-Casp8 cleaves RIP1 to disintegrate the necrosome. It has been unclear how the Casp8 blockade of necroptosis is eliminated naturally. Here, we show that pro-Casp8 within the necrosome can be inactivated by phosphorylation at Thr265 (pC8^T265). pC8^T265 occurs in vitro in various necroptotic cells and in the cecum of TNF-treated mice. p90 RSK is the kinase of pro-Casp8. It is activated by a mechanism that does not need ERK but PDK1, which is recruited to the RIP1-RIP3-MLKL-containing necrosome. Phosphorylation of pro-Casp8 at Thr265 can substitute for zVAD to permit necroptosis in vitro. pC8^T265 mimic T265E knockin mice are embryonic lethal due to unconstrained necroptosis, and the pharmaceutical inhibition of RSK-mediated pC8^T265 diminishes TNF-induced cecum damage and lethality in mice by halting necroptosis. Thus, phosphorylation of pro-Casp8 at Thr265 by RSK is an intrinsic mechanism for passing the Casp8 checkpoint of necroptosis.

体外坏死病诱导通常需要zVAD抑制caspase-8（Casp8），因为pro-Casp8裂解RIP1使其坏死。尚不清楚如何自然消除Casp8坏死性神经病的阻滞作用。在这里，我们显示坏死体内的pro-Casp8可通过Thr265（pC8 ^T265）的磷酸化而失活。的pC8 ^T265发生在体外以各种necroptotic细胞和TNF处理的小鼠的盲肠。p90 RSK是pro-Casp8的激酶。它由不需要ERK而是PDK1的机制激活，该机制被募集到包含RIP1-RIP3-MLKL的坏死体中。前Casp8在Thr265处的磷酸化可以替代zVAD，从而在体外使尸体坏死。pC8 ^T265模仿性的T265E敲入小鼠由于不受约束的坏死性死亡而具有胚胎致死性，而RSK介导的pC8 ^T265的药物抑制作用则通过中止坏死性死亡来减少TNF诱导的盲肠损伤和致死性。因此，RSK在Thr265处对pro-Casp8的磷酸化是通过坏死性Casp8检查点的内在机制。