RIPK1 可防止发育过程中由 TRADD 驱动但与 TNFR1 无关的细胞凋亡。

RIPK1 prevents TRADD-driven, but TNFR1 independent, apoptosis during development.

机构信息

The Walter and Eliza Hall Institute for Medical Research, 1G Royal Parade, Parkville, Melbourne, VIC, 3050, Australia.

Department of Medical Biology, University of Melbourne, Parkville, VIC, 3050, Australia.

出版信息

Cell Death Differ. 2019 May;26(5):877-889. doi: 10.1038/s41418-018-0166-8. Epub 2018 Sep 5.

Abstract

RIPK1 is an essential downstream component of many pattern recognition and death receptors. RIPK1 can promote the activation of caspase-8 induced apoptosis and RIPK3-MLKL-mediated necroptosis, however, during development RIPK1 limits both forms of cell death. Accordingly, Ripk1 mice present with systemic cell death and consequent multi-organ inflammation, which is driven through the activation of both FADD-caspase-8 and RIPK3-MLKL signaling pathways causing perinatal lethality. TRADD is a death domain (DD) containing molecule that mediates signaling downstream of TNFR1 and the TLRs. Following the disassembly of the upstream receptor complexes either RIPK1 or TRADD can form a complex with FADD-caspase-8-cFLIP, via DD-DD interactions with FADD, facilitating the activation of caspase-8. We show that genetic deletion of Ripk1 licenses TRADD to complex with FADD-caspase-8 and activates caspase-8 during development. Deletion of Tradd provided no survival advantage to Ripk1 animals and yet was sufficient to reduce the systemic cell death and inflammation, rescue the intestinal and thymic histopathologies, reduce cleaved caspases in most tissues and rescue the anemia observed in Ripk1 neonates. Furthermore, deletion of Ripk3 is sufficient to rescue the neonatal lethality of Ripk1Tradd animals and delays but does not completely prevent early mortality. Although Ripk3 deletion provides a significant survival advantage, Ripk1TraddRipk3 animals die between 22 and 49 days, are runty compared to littermate controls and present with splenomegaly. These findings reveal a new mechanism by which RIPK1 limits apoptosis through blocking TRADD recruitment to FADD and preventing aberrant activation of caspase-8.

摘要

RIPK1 是许多模式识别和死亡受体的重要下游成分。RIPK1 可以促进 caspase-8 诱导的凋亡和 RIPK3-MLKL 介导的坏死的激活,然而,在发育过程中,RIPK1 限制了这两种形式的细胞死亡。因此,Ripk1 小鼠表现出全身细胞死亡和随之而来的多器官炎症,这是通过激活 FADD-caspase-8 和 RIPK3-MLKL 信号通路引起的,导致围产期致死。TRADD 是一种含有死亡域 (DD) 的分子,介导 TNFR1 和 TLR 下游的信号转导。在上游受体复合物解体后,RIPK1 或 TRADD 都可以通过 DD-DD 与 FADD 的相互作用与 FADD-caspase-8-cFLIP 形成复合物,从而促进 caspase-8 的激活。我们表明,Ripk1 的基因缺失允许 TRADD 与 FADD-caspase-8 形成复合物,并在发育过程中激活 caspase-8。Tradd 的缺失对 Ripk1 动物没有生存优势,但足以减少全身细胞死亡和炎症,挽救肠道和胸腺组织病理学,减少大多数组织中的切割 caspase,并挽救 Ripk1 新生儿的贫血。此外,Ripk3 的缺失足以挽救 Ripk1Tradd 动物的新生儿致死性,并延迟但不能完全阻止早期死亡。尽管 Ripk3 的缺失提供了显著的生存优势,但 Ripk1TraddRipk3 动物在 22 至 49 天之间死亡,与同窝对照相比体型较小,并伴有脾肿大。这些发现揭示了一种新的机制,即 RIPK1 通过阻止 TRADD 招募到 FADD 并防止 caspase-8 的异常激活来限制细胞凋亡。

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