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Activation of the NOD1 and NOD2 signaling pathways

NOD1 和 NOD2 信号通路的激活

基本信息

批准号：
10172844
负责人：
Arina Marijke Keestra-Gounder
金额：
$ 22.64万
依托单位：
UNIVERSITY OF COLORADO DENVER
依托单位国家：
美国
项目类别：
财政年份：
2020
资助国家：
美国
起止时间：
2020-06-01 至 2022-11-30
项目状态：
已结题

项目摘要

PROJECT SUMMARY NOD1 and NOD2 are pattern recognition receptors that sense fragments of bacterial peptidoglycans, and are able to detect perturbations in cellular processes such as the modulation of the actin cytoskeleton and disturbance in endoplasmic reticulum (ER) homeostasis. Under different stressful conditions, such as bacterial and viral infections, protein misfolding and perturbations in calcium homeostasis, the ER is unable to maintain homeostasis and activates the unfolded protein response (UPR). Upon ER stress three transmembrane receptors, IRE1, PERK and ATF6 are activated and regulate biological processes such as inhibition of protein translation, autophagy, and inflammation to reestablish cellular homeostasis. NOD1 and NOD2 have been implicated in ER stress-induced inflammation, by acting downstream in the UPR to induce NF-B activation and IL-6 production. The exact mechanism how NOD1 and NOD2 can sense ER stress is currently unknown. NOD1 and NOD2 can also sense the activation of small Rho GTPases such as Rac1. Rac1 activation leads to membrane ruffling as well as activation of the transcription factor NF-B. We and others have shown that NOD1 and NOD2 interact with Rac1 at the cell membrane. The underlying mechanism of Rac1-mediated NOD1 and NOD2 activation is currently unknown. In the application we propose to study the mechanisms of peptidoglycan-independent activation of NOD1 and NOD2 by modulation of the actin cytoskeleton and thapsigargin-induced ER stress. Our central hypothesis is that NOD1 and NOD2 can detect cellular perturbations independent of peptidoglycan recognition. We will test key aspects of our hypothesis using the logical and innovative approach outlined in the following specific aims. Specific Aim 1. Determine the role of NOD1 and NOD2 in sensing ER stress. We will determine the contribution of calcium flux from the ER to the mitochondria in ER stress induced NOD1 and NOD2 activation. We will test our hypothesis that mitochondria damaged by ER stress release damage-associated molecular patterns (DAMPs) that activate NOD1 and NOD2. Specific Aim 2. Perturbations in cellular processes determines NOD1 and NOD2 localization. We will investigate the cellular localization of NOD1 and NOD2 in cells treated with thapsigargin to induce ER stress and in cells that express active Rac1 or Rac1 mutant forms that either induce cytoskeletal remodeling or NF-B activation. Characterizing and understanding the mechanisms of peptidoglycan-independent NOD1 and NOD2 activation provides a plausible explanation for the observation that viruses and parasites trigger NOD1 and NOD2 signaling. These findings are innovative new concepts and would markedly influence the current concepts of NOD1 and NOD2 biology.

项目概要 NOD1 和 NOD2 是感知细菌肽聚糖片段的模式识别受体，并能够检测细胞过程中的扰动，例如肌动蛋白细胞骨架的调节和内质网（ER）稳态紊乱。在不同的压力条件下，例如细菌病毒感染、蛋白质错误折叠和钙稳态扰动，ER 无法维持稳态并激活未折叠蛋白反应（UPR）。 ER应激后三跨膜受体 IRE1、PERK 和 ATF6 被激活并调节生物过程，例如抑制蛋白质翻译、自噬和炎症以重建细胞稳态。 NOD1 和 NOD2 已通过作用于 UPR 下游诱导 NF-κB 激活，参与 ER 应激诱导的炎症和IL-6的生产。 NOD1 和 NOD2 感知 ER 应激的确切机制目前尚不清楚。 NOD1 和 NOD2 还可以感知小型 Rho GTP 酶（例如 Rac1）的激活。 Rac1 激活导致膜褶皱以及转录因子 NF-κB 的激活。我们和其他人已经证明 NOD1 和 NOD2 在细胞膜上与 Rac1 相互作用。 Rac1介导的潜在机制 NOD1 和 NOD2 的激活目前未知。在应用中，我们建议研究其机制通过调节肌动蛋白细胞骨架，独立于肽聚糖激活 NOD1 和 NOD2 毒胡萝卜素诱导的内质网应激。我们的中心假设是 NOD1 和 NOD2 可以检测细胞与肽聚糖识别无关的扰动。我们将使用以下方法来测试我们假设的关键方面：以下具体目标概述了逻辑和创新的方法。具体目标 1. 确定 NOD1 和 NOD2 在感知 ER 应激中的作用。我们将确定内质网应激诱导的 NOD1 和 NOD2 激活中钙离子从 ER 流向线粒体的贡献。我们将检验我们的假设，即线粒体受到内质网应激释放损伤相关分子的损伤激活 NOD1 和 NOD2 的模式（DAMP）。具体目标 2. 细胞过程的扰动决定了 NOD1 和 NOD2 的定位。我们将研究用毒胡萝卜素处理的细胞中 NOD1 和 NOD2 的细胞定位以诱导 ER 应激以及表达活性 Rac1 或 Rac1 突变体形式的细胞，这些突变体要么诱导细胞骨架重塑，要么 NF-κB 激活。表征和理解不依赖于肽聚糖的 NOD1 和 NOD2 激活为病毒和寄生虫触发 NOD1 的观察提供了合理的解释和 NOD2 信号传导。这些发现是创新的新概念，将对当前的 NOD1 和 NOD2 生物学概念。