Rip Proteins in Innate Immune Signaling

细胞因子TNF、病原体识别Toll样受体（TLR）和核苷酸结合 寡聚化结构域（NOD）蛋白部分地通过激活 转录因子NF-κ B。我们已发表的工作揭示了Rip 1作为TNF-α的关键介导剂， TLR 3/4，Trif依赖性NF-κ B通路。我们已经证明Rip 1的激酶活性不是必需的，但是 相反，Rip 1的泛素修饰对于TNF诱导的NF-κ B活化和细胞因子 生产除了介导Trif途径外，Rip 1还参与了RNA识别。 然而，细胞溶质Rig-l/Mda 5解旋酶，Rip 1缺陷如何损害先天性抗病毒药物仍有待证明。 应答为了解决这个问题，我们将分离Rip 1缺陷的巨噬细胞和树突状细胞， 来自造血嵌合体和条件性ripl小鼠，并将用病毒感染这些细胞类型， 检查抗病毒信号传导（Aim 1）。我们的初步研究揭示了Rip 1在细胞凋亡中的一种新的调节作用。 干扰素调节因子7（IRF-7）的泛素化和激活，IRF-7是一种对型 干扰素生产。然而，Rip 1如何调节IRF-7活动尚不清楚，这是当前提案的重点 (Aim 1）。另一个目标是确定多聚泛素化Rip 1是否是激活 在病毒感染的细胞中的NF-xB和/或IRF-7，并测试不能泛素修饰Rip 1是否导致 先天性抗病毒应答受损（目的2）。同样，我们对相关Rip 1蛋白的初步研究， Rip 2，在用NOD 2配体MDP处理的细胞中发现内源性Rip 2多泛素化，并暗示了 泛素活化激酶Tak 1和E2泛素结合酶Ubc 13在NOD 2介导的NF-κ B中的作用 activation.在目标3中，我们将测试NOD 2介导的NF-κ B中对聚遍在蛋白化Rip 2的需求 激活和先天免疫反应，并将确定如何疾病相关的等位基因NOD 2 影响Rip 2的募集和多聚泛素化。总的来说，我们的研究表明， 调节先天免疫反应，提高了负责泛素的酶 Rip蛋白的修饰可以在治疗上靶向治疗感染性疾病或慢性炎症。 炎症性疾病。 细菌和病毒被设计用来抵抗感染的受体识别。这些受体的反应是 产生具有抗菌和抗病毒活性的可溶性因子。我们的研究重点是里普 Rip蛋白有助于宿主对感染的应答，其目的是Rip蛋白的活性可以被 在人类疾病中，根据需要通过药物刺激或减弱。

The cytokine TNF, the pathogen recognition Toll-like receptors (TLRs) and the nucleotide binding oligomerization domain (NOD) proteins mediate host defense against infection in part by activating the transcription factor NF-icB. Our published work reveals Rip1 as a critical mediator of the TNF- and the TLR3/4, Trif-dependent NF-icB pathways. We have shown that the kinase activity of Rip1 is not required, but rather the ubiquitin modification of Rip1 is essential for TNF-induced NF-KB activation and cytokine production. In addition to mediating the Trif pathway, Rip1 has been implicated in dsRNA recognition by the cytosolic Rig-l/Mda5 helicases, however, it remains to be proven how a Rip1 deficiency impairs innate antiviral responses. To address this question, we will isolate Rip1-deficient macrophages and dendritic cells from hematopoeitic chimeras and conditional ripl mice and will infect these cell types with viruses and examine anti-viral signaling (Aim 1). Our preliminary studies reveal a novel regulatory role for Rip1 in the ubiquitination and activation of the interferon regulatory factor 7 (IRF-7), a transcription factor critical for type interferon production. Yet, how Rip1 regulates IRF-7 activity is unclear and a focus of the current proposal (Aim 1). An additional goal is to determine whether polyubiquitinated Rip1 is required for the activation of NF-xB and/or IRF-7 in virally infected cells and to test whether an inability to ubiquitin modify Rip1 results in impaired innate anti-viral responses (Aim 2). Similarly, our preliminary studies on the related Rip1 protein, Rip2, find endogenous Rip2 polyubiquitinated in cells treated with the NOD2 ligand, MDP and implicate the ubiquitin activated kinase Tak1 and the E2 ubiquitin conjugating enzyme Ubc13 in NOD2-mediated NF-icB activation. In Aim 3, we will test a requirement for polyubiquitinated Rip2 in NOD2-mediated NF-KB activation and in innate immune responses and will determine how disease associated alleles of NOD2 affect the recruitment and polyubiquitination of Rip2. Collectively, our studies suggest that ubiquitin regulates innate immune responses, raising the possibility that the enzymes responsible for the ubiquitin modification of Rip proteins may be targeted therapeutically to treat infectious disease or chronic inflammatory disease. Bacteria and viruses are recognized by receptors designed to fight infection. These receptors respond by producing soluble factors that have anti-bacterial and anti-viral activity. Our research is focused on how Rip proteins contribute to host responses against infection with the goal that the activity of Rip proteins can be stimulated or attenuated by drugs as needed, in human disease.