Rip Proteins in Innate Immune Signaling

描述（由申请人提供）：包含丝氨酸/苏氨酸激酶Ripk1的死亡结构域是tnf诱导的信号复合物的核心成分，介导NFκB和MAP激酶激活、细胞凋亡和另一种不依赖caspase的细胞死亡形式，称为坏死坏死。在无偏倚的全基因组siRNA筛选坏死性坏死的调节因子，Ripk1，它的去泛素酶Cyld，相关的Ripk3以及属于干扰素和toll样受体信号系统的其他蛋白质被确定。这些研究以及使用变构Ripk1激酶抑制剂或ripk3缺陷小鼠的研究证实，坏死坏死是宿主抵抗病毒感染的重要防御机制。坏死坏死需要Ripk1和Ripk3的激酶活性，但Rip激酶如何启动和执行坏死细胞死亡尚不清楚。我们已经证明，Ripk1在TLR3和rig - 1介导的核酸感知途径中具有TNF以外的其他信号功能。我们的初步研究还表明，Ripk1参与了一个涉及Sting、Tbk1和Irf3的细胞质DNA传感通路。总的来说，这些研究预测了Ripk1在先天抗病毒免疫中的核心作用，然而与Ripk1缺乏相关的围产期死亡率已经排除了体内分析。目前的目标是使用我们已经产生的条件Ripk1小鼠来测试抗病毒先天免疫反应中对Ripk1的需求。我们还在Ripk1基因座中引入了一个突变，该突变会损害Ripk1的激酶活性。我们对Ripk1激酶失活mef和巨噬细胞的初步研究发现，这些细胞分别受到TNF-和tlr3诱导的坏死性坏死的保护。本提案的另一个目的是在这些新设计的Ripk1激酶失活小鼠中检查病毒启动的坏死性坏死对宿主防御的贡献。除了病毒诱导的损伤和炎症外，Rip激酶还响应组织损伤时释放的称为危险相关分子模式（DAMPs）的非微生物信号。这些研究的长期目标是在不损害先天免疫的情况下选择性地抑制无菌炎症中的Rip激酶。

DESCRIPTION (provided by applicant): The death domain containing serine/threonine kinase Ripk1 is the core component of TNF-induced signaling complexes mediating NFκB and MAP kinase activation, apoptosis and an alternative form of caspase independent cell death called necroptosis. In unbiased genome wide siRNA screens for regulators of necroptosis, Ripk1, its deubiquitinase Cyld, the related Ripk3 as well as other proteins belonging to the interferon and Toll-like receptor signaling systems were identified. These studies and those using an allosteric Ripk1 kinase inhibitor or Ripk3-deficient mice establish necroptosis as a prominent host defense against viral infection. Necroptosis requires the kinase activities of Ripk1 and Ripk3 but precisely how Rip kinases initiate and execute necroptotic cell death is unknown. We have shown that Ripk1 has additional signaling functions beyond TNF, in nucleic acid sensing pathways mediated by TLR3 and Rig-I. Our preliminary studies additionally implicate Ripk1 in a cytosolic DNA sensing pathway involving Sting, Tbk1 and Irf3. Collectively, these studies predict a central role for Ripk1 in innate anti-viral immunity, however the perinatal lethality associated with a Ripk1-deficiency has precluded in vivo analyses. Goals of the current proposal are to test a requirement for Ripk1 in the anti-viral innate immune response using the conditional Ripk1 mice we have generated. We have also introduced a mutation into the Ripk1 locus that impairs the kinase activity of Ripk1. Our preliminary studies in Ripk1 kinase inactive MEFs and macrophages find these cells protected from TNF- and TLR3-induced necroptosis, respectively. An additional objective of this proposal is to examine the contribution of viral-initiated necroptosis to host defense in these newly engineered Ripk1 kinase inactive mice. In addition to virus-induced injury and inflammation, Rip kinases respond to non-microbial signals called danger-associated molecular patterns (DAMPs) released upon tissue injury. The long-term goal of these studies is to selectively inhibit Rip kinases in sterile inflammation without impairing innate immunity.