ROS-dependent STIM1 activation and Ca2+ entry in lung inflammation

描述（由申请人提供）：在人或动物模型中的脓毒症期间，内毒素激活先天免疫细胞通过促炎细胞因子的过度产生导致全身性炎症，从而导致急性肺损伤（ALI）。在此过程中，几种途径在内皮细胞中起作用，包括氧化应激、细胞内Ca 2+超载和细胞器功能障碍以及内皮细胞死亡。尽管关于导致内毒素诱导的ALI的潜在分子机制的大量信息，该途径中的几个元件仍有待鉴定。鉴定ALI中的分子组分对于理解ALI发病机制的进展和鉴定治疗该疾病的潜在靶点至关重要。已知旁分泌和自分泌衍生的氧化剂都调节内皮细胞的氧化还原生物学。我们最近的研究表明，免疫细胞和自分泌来源的氧化剂激活肺内皮细胞Ca 2+信号，而阻断氧化剂的产生抑制Ca 2+信号诱导的促炎反应。此外，我们最近已经证明，ER居民Ca 2+传感器STIM 1也是ROS的目标。因此，STIM 1的氧化促进质膜Ca 2+通道Orai 1的激活，从而提高胞质Ca 2+水平和基因转录的调节。STIM操作通道提高细胞内Ca 2+水平和诱导转录活性的能力促使我们研究其在内毒素引起的炎症中的作用。我们在本申请中提出的工作假设是，血管炎症是由LPS诱导的ROS过度产生导致的，ROS过度产生导致Ca 2+信号转导的扰动、线粒体功能和能量代谢的破坏、血管张力和血管完整性的丧失。本项目的具体目的是：1）表征ROS诱导的Ca 2+信号在内皮细胞活化和炎症中的作用; 2）检查靶向CRAC通道组分是否控制血管炎症反应。我们的目标是表征涉及ROS，Ca 2+和相关细胞内事件的新机制，这些事件在体外或体内暴露于可能导致脓毒症发展的内毒素后调节内皮细胞中的基因转录。这些研究将为调节内皮功能和促进ALI发病机制的基本机制提供新的见解。 公共卫生相关性：内毒素诱导的急性肺损伤是一种炎症性疾病，据报道是多微生物感染性挑战导致的最常见的器官功能障碍形式。本申请中提出的研究不仅应确定导致器官功能障碍的细胞事件，而且还可能开发降低急性肺损伤严重程度的干预措施。

DESCRIPTION (provided by applicant): During sepsis in either humans or in animal models, activation of innate immune cells by endotoxin leads to systemic inflammation via overproduction of proinflammatory cytokines resulting in acute lung injury (ALI). During this process, several pathways are operative in endothelial cells including, oxidative stress, intracellular Ca2+ overload and organelle dysfunction and endothelial cell death. Despite substantial information regarding the underlying molecular mechanisms that lead to endotoxin-induced ALI, several elements in the pathway remain to be identified. Identification of the molecular components in ALI is of critical importance in order to understand the progression of ALI pathogenesis and to identify potential targets for treatment of the disease. Both paracrine and autocrine-derived oxidants are known to modulate the redox biology of the endothelial cells. Our recent studies demonstrate that both immune cell- and autocrine-derived oxidants activate pulmonary endothelial Ca2+ signaling, while blockade of oxidant production inhibits Ca2+ signaling induced proinflammatory responses. Further, we have recently demonstrated that the ER resident Ca2+ sensor STIM1 is also a ROS target. Hence, oxidation of STIM1 facilitates activation of the plasma membrane Ca2+ channel Orai1, thereby elevating cytosolic Ca2+ levels and regulation of gene transcription. The ability of STIM-operated channels to elevate intracellular Ca2+ levels and induce transcriptional activity prompted us to investigate its role in inflammation caused by endotoxin. Our hypothesis for work proposed in this application is that vascular inflammation results from LPS-induced ROS overproduction which leads to perturbation of Ca2+ signaling, disruption of mitochondrial function and energy metabolism, loss of vascular tone and vascular integrity. The specific aims of this project are: 1) Characterize the role of ROS-induced Ca2+ signaling in endothelial cell activation and inflammation; and 2) To examine whether targeting the CRAC channel components control vascular inflammatory responses. Our goal is to characterize novel new mechanisms involving ROS, Ca2+ and related intracellular events that modulate gene transcription in endothelial cells after either in vitro or in vivo exposure to endotoxin which could contribute to development of sepsis. These investigations will provide new insights into the fundamental mechanisms that modulate endothelial function and contribute to the ALI pathogenesis. PUBLIC HEALTH RELEVANCE: Endotoxin-induced acute lung injury is an inflammatory disease, which is reported to be the most common form of organ dysfunction resulting from polymicrobial septic challenge. The studies proposed in this application should not only identify cellular events leading to organ dysfunction, but also are likely to develop the interventions to decrease the severity of acute lung injury.