Rip Proteins in Innate Immune Signaling

细胞因子肿瘤坏死因子、病原体识别Toll样受体及其核苷酸结合 寡聚化结构域(NOD)蛋白部分通过激活 转录因子核因子-ICB。我们发表的研究表明，RIP1是肿瘤坏死因子的关键调节因子--以及 TLR3/4，Trif依赖的NF-ICB通路。我们已经证明，RIP1的激酶活性不是必需的，但 相反，RIP1的泛素修饰对于肿瘤坏死因子诱导的核因子-KB的激活和细胞因子是必不可少的 制作。除了介导Trif途径外，RIP1还参与dsRNA的识别 然而，胞浆RIG-L/MDA5解旋酶的缺失如何损害先天抗病毒作用仍有待证实 回应。为了解决这个问题，我们将分离缺乏RIP1的巨噬细胞和树突状细胞 来自造血系嵌合体和条件Ripl小鼠，并将感染这些细胞类型的病毒和 检查抗病毒信号(目标1)。我们的初步研究揭示了RIP1在 干扰素调节因子7(IRF-7)的泛素化和激活 干扰素的生产。然而，RIP1如何调控IRF-7活动尚不清楚，也是当前提案的重点 (目标1)。另一个目标是确定多泛素化的RIP1是否需要激活 病毒感染细胞中的核因子-xB和/或IRF-7，并测试泛素修饰RIP1的能力是否导致 先天抗病毒反应受损(目标2)。同样，我们对相关RIP1蛋白的初步研究， RIP2，在用NOD2配体MDP处理的细胞中发现内源性RIP2多泛素化，并涉及 NOD2介导的核因子-ICB中泛素活化蛋白激酶Tak1和泛素结合酶UBC13的表达 激活。在目标3中，我们将测试NOD2介导的核因子-KB对多泛素化RIP2的需求 激活和先天免疫反应，并将决定NOD2的疾病相关等位基因 影响RIP2的募集和多泛素化。总而言之，我们的研究表明，泛素 调节先天免疫反应，增加负责泛素的酶的可能性 Rip蛋白的修饰可能被靶向治疗感染性疾病或慢性疾病 炎症性疾病。 细菌和病毒是由旨在对抗感染的受体识别的。这些受体通过 产生具有抗细菌和抗病毒活性的可溶性因子。我们的研究重点是Rip如何 蛋白质有助于宿主对感染的反应，其目标是Rip蛋白的活性可以 在人类疾病中，根据需要由药物刺激或减弱。

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.