Innate immune signal transduction specificity in inflammatory disease

摘要 先天免疫系统识别病原体并对其作出反应。在这样做的过程中， 系统负责启动细胞因子反应，旨在调整适应性免疫系统以 根除有害生物。这一过程必须受到严格监管，因为太多的活动可能会导致 炎症性疾病。因为炎症性疾病的特点是持续的先天免疫 激活和细胞因子释放--控制先天免疫反应下调的机制 在限制炎症病理方面起着至关重要的作用。本拨款申请旨在研究这方面的机制。 关注NOD2蛋白(CARD15基因)和On的信号转导机制下调 NOD2的S在启动和维持细胞因子反应中的作用。NOD2蛋白负责一种 炎症性疾病的数量包括BLAU综合征(一种家族性肉芽肿病)， 早发性结节病和15%-20%的遗传性克罗恩病。NOD2被激活以响应 细胞内同时接触革兰氏阳性和革兰氏阴性细菌后，它有助于协调核因子B 通过赖氨酸-63(K63)连接的多泛素化新位点(K285)激活和释放细胞因子 IKK支架蛋白NEMO。我们最近扩展了这一发现，以表明主要的细胞外 先天免疫信号受体，Toll样受体(TLRs)，也需要K285 Nemo泛素化来 这项工作表明，对翻译后修饰的调节 IKK支架蛋白，NEMO，有助于协调细胞内和细胞外固有的串扰 免疫途径，还有助于调节细胞因子的身份、数量和持续时间 释放了。这些发现还表明，对于核因子B信号，多个先天免疫信号通路 在NEMO上收敛，NEMO上的翻译后修饰作为控制NEMB的变阻器 活动。因此，这些翻译后修饰也可能是靶向于 下调NOD2和其他先天免疫信号通路激活的核因子B反应。这个 这项授权的中心假设是下调NOD2和TLR刺激的NF？B激活是 在避免炎症病理方面是最重要的。未能适当下调核因子B的反应 而替代(MAP激酶)信号通路之间的协调可能是 炎症性疾病的病理生理学。对这些下调途径的研究可能会导致 对于这些疾病的病理生理学的新见解和新的可用药靶点 帮助治疗这些疾病。为了开始解决这一重要问题，我们已经产生了重大的 初步数据。我们在NEMO上发现了一个新的先天免疫诱导的磷酸化位点 控制Nemo泛素化，从而控制最终的核因子B的激活。我们还确定了一个 通过意外的MAP3K抑制NEMO泛素化和转换的信号通路 先天免疫信号从核因子B活性转向p38活性。本次拨款申请目的的具体目的 为了确定先天免疫诱导的核因子B活性的生化机制 下调，以确定MEKK4在先天下游决定信号特异性的功能 免疫系统的激活，并确定这些信号通路在脑出血的病理生理学中的作用。 炎症性疾病。层级摘要 作为人类，我们经常接触到细菌、真菌和病毒，而我们 必须对这些病原体做出反应，这样我们才不会被感染。在回应之后 对于这些病原体，如果我们的免疫系统没有失活，我们就会发展成炎症 哮喘、炎症性肠病、多发性硬化症和 动脉粥样硬化(心脏和血管疾病)。像这样的炎症性疾病 广泛人群(婴儿)发病和死亡的重要原因 至长者)。由于降低炎症反应的重要性，我们的 人体已经开发出复杂的机制来抑制炎症 回应。这项拨款申请旨在研究抑制这种现象的机制。 炎症反应和这种抑制有缺陷的机制 炎症性疾病。这项工作旨在帮助确定炎症的原因 并旨在确定药物干预这些疾病的新靶点 使人衰弱的疾病。

Abstract The innate immune system recognizes and responds to pathogenic organisms. In doing so, this system is responsible for initiating a cytokine response designed to tailor the adaptive immune system to eradicate the offending organism. This process must be tightly regulated as too much activity can lead to inflammatory disease. Because inflammatory diseases are characterized by prolonged innate immune activation and cytokine release, the mechanisms controlling downregulation of the innate immune response are paramount in limiting inflammatory pathology. This grant application aims to study the mechanisms of this downregulation by focusing on the signal transduction mechanisms of NOD2 protein (CARD15 gene) and on NOD2's role in initiating and maintaining the cytokine response. The NOD2 protein is responsible for a number of inflammatory disorders including Blau Syndrome (a familial granulomatosis disease), a subset of Early Onset Sarcoidosis and for 15-20% of genetic Crohn's Disease. NOD2 is activated in response to intracellular exposure to both gram-positive and gram-negative bacteria after which it helps to coordinate NF¿B activation and cytokine release through the lysine-63 (K63)-linked polyubiquitination of a novel site (K285) on the IKK scaffolding protein NEMO. We have recently extended this finding to show that the major extracellular innate immune signaling receptors, the Toll-like Receptors (TLRs), also require K285 NEMO ubiquitination to properly signal through NF¿B. This work suggests that regulation of the post-translational modifications on the IKK scaffolding protein, NEMO, helps to coordinate cross-talk between intracellular and extracellular innate immune pathways and also helps to regulate the identity, the amount and the duration of cytokines that are released. These findings also suggest that for NF¿B signaling, multiple innate immune signaling pathways converge on NEMO and that the post-translational modifications on NEMO serve as a rheostat to control NF¿B activity. As such, these post-translational modifications may also be targets for molecules aimed at downregulating the NF¿B response activated by NOD2 and other innate immune signaling pathways. The central hypothesis of this grant is that downregulation of NOD2 and TLR-stimulated NF¿B activation is paramount in avoiding inflammatory pathology. Failure to properly downregulate the NF¿B response and coordinate between alternative (MAP kinase) signaling pathways may underlie the pathophysiology of inflammatory disorders. Study of these pathways of downregulation could lead both to novel insight regarding the pathophysiology of these diseases and to novel druggable target to help treat these diseases. To begin to tackle this important problem, we have generated significant preliminary data. We have identified a novel innate immune-induced phosphorylation site on NEMO that controls NEMO ubiquitination and therefore, controls ultimate NF¿B activation. We have also identified a signaling pathway operating through an unexpected MAP3K which inhibits NEMO ubiquitination and shifts innate immune signaling from NF¿B activity toward p38 activity. The Specific Aims of this grant application aim to determine the biochemical mechanisms by which innate immune-induced NF¿B activity can be downregulated, to determine the function of MEKK4 in dictating signal specificity downstream of innate immune system activation and to determine the role of these signaling pathways in the pathophysiology of inflammatory disease. Lay Summary As humans, we are constantly exposed to bacteria, fungi and viruses, and we must respond to these pathogens so that we do not become infected. After responding to these pathogens, if our immune systems do not deactivate, we develop inflammatory disorders such as asthma, inflammatory bowel disease, multiple sclerosis and atherosclerosis (heart and vascular disease). Inflammatory diseases such as these are a significant cause of morbidity and mortality across a wide range of populations (infants to elderly). Due to the importance of downregulating the inflammatory response, our bodies have developed sophisticated mechanisms to dampen the inflammatory response. This grant application aims to study the mechanisms that dampen this inflammatory response and the mechanisms by which this dampening is faulty in inflammatory disease. This work aims to help determine the causes of inflammatory disease and aims to identify novel targets for pharmaceutical intervention in these debilitating disorders.