Rip Proteins in Innate Immune Signaling

含有丝氨酸/苏氨酸激酶Ripk1的死亡结构域是肿瘤坏死因子诱导的核心成分 介导核因子B和MAP激酶激活、凋亡的信号复合体和另一种形式的 半胱氨酸氨基转移酶非依赖性细胞死亡称为坏死性下垂。在全基因组无偏见的siRNA中筛选调节器 Ripk1、其脱泛素酶CyLD、相关的RIPK3以及其他属于 确定了干扰素和Toll样受体信号系统。这些研究和那些使用 变构Ripk1激酶抑制剂或RIPK3缺陷小鼠建立坏死性下垂作为突出的宿主防御 对抗病毒感染。坏死性下垂需要Ripk1和RIPK3的激酶活性，但确切地说Ripk1和RIPK3 激酶启动和执行坏死性细胞死亡尚不清楚。我们已经证明了Ripk1具有额外的 在TLR3和RIG-I介导的核酸传感通路中，信号转导功能超过了肿瘤坏死因子。我们的 初步研究还发现Ripk1还参与了涉及Sting、Tbk1的胞质DNA传感通路 和IRF3。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缺乏症相关的围产期致死性排除了活体分析。当前的目标 建议测试Ripk1在抗病毒先天免疫反应中的要求，使用条件 我们培育的Ripk1小鼠。我们还在Ripk1基因座引入了一个突变，它会损害 Ripk1的激酶活性。我们对Ripk1激酶失活的MEF和巨噬细胞的初步研究发现 分别保护细胞免受肿瘤坏死因子和TLR3诱导的坏死性下垂。这样做的另一个目标是 建议检查病毒引发的坏死性下垂对宿主防御的贡献 经过改造的Ripk1激酶失活小鼠。除了病毒诱导的损伤和炎症外，Rip激酶 对被称为危险相关分子模式(DAMP)的非微生物信号的响应 组织损伤。这些研究的长期目标是选择性地抑制无菌炎症中的Rip激酶 而不会损害先天免疫力。

The death domain containing serine/threonine kinase Ripk1 is the core component of TNF-induced signaling complexes mediating NF¿B 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.