Microtubule-associated regulation of acute lung injury

 描述(申请人提供)：肺部炎症和内皮通透性改变在急性肺损伤(ALI)和急性呼吸窘迫综合征(ARDS)的病理生理学中起着重要作用，这两种疾病与高死亡率相关。目前治疗的低效率可能部分是由于专注于旨在预防ALI发病的药物治疗，而内源性反馈机制虽然在临床上更具相关性，但对减轻炎症激活和内皮屏障功能障碍的机制仍知之甚少。我们在前一个周期的研究发现了微管外周网络在控制肺内皮细胞屏障功能中的新作用。我们发现，屏障增强型激动剂如肝细胞生长因子刺激微管外周生长，促进Rac GTPase依赖的信号转导，减弱Rho GTPase依赖的信号转导，从而导致血管泄漏的下调。我们定义了一个新的范式，通过微管相关的鸟嘌呤核苷酸交换因子ASEF和Global-H1对Rac和Rho通路进行双重调节，并证明了微管在Rac-Rho串扰和控制内皮通透性的机制中发挥的重要作用。然而，ALI发病和缓解的微管依赖调节的整个机制，特别是炎症级联反应的微管依赖调节，仍然知之甚少。在筛选与对照组和炎症肺内皮细胞微管相关的潜在信号蛋白时，我们发现炎症信号负调控因子SOCS1与微管成分有关。这一偶然的发现表明，微管细胞骨架与控制内皮炎症和炎症诱导的通透性之间存在新的联系。目前，微管在细菌壁化合物、细胞因子等调节内皮屏障反应中的作用仍不清楚。我们假设，调控细胞炎症反应的细胞反馈机制关键需要微管辅助的SOCS1靶向亚膜室，在那里它与其细胞因子受体和TLR相关的蛋白靶点相互作用。利用脂多糖诱导的ALI的细胞、体外和体内模型，这一应用将表征SOCS1对内毒素诱导的炎症的调节，研究微管参与调控SOCS1的抗炎功能，并将识别活性微管辅助的SOCS1转运和亚膜靶向的分子机制。该项目的结果将描绘新的微管依赖的调节肺屏障功能障碍和炎症的机制，这可能导致发现一组新的治疗ALI/ARDS的药物分子。

 DESCRIPTION (provided by applicant): Lung inflammation and alterations in endothelial permeability play a major role in the pathophysiology of acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), the conditions associated with high mortality rates. Low efficiency of current therapies may be explained in part by focus on drug treatments aimed at prevention of the onset of ALI, while endogenous feedback mechanisms which subside inflammatory activation and endothelial barrier dysfunction, although much more clinically relevant, remain poorly understood. Our studies in the previous cycle identified a novel role of microtubule peripheral network in the control of lung endothelial barrier function. We discovered that stimulation of microtubule peripheral growth by barrier enhancing agonists, such as hepatocyte growth factor, promoted Rac GTPase-dependent and attenuated Rho GTPase-dependent signaling, thus leading to downregulation of vascular leak. We defined a novel paradigm of dual regulation of Rac and Rho pathways by microtubule-associated guanine nucleotide exchange factors Asef and GEF-H1 and demonstrated essential role of the microtubules in the mechanisms of Rac-Rho crosstalk and control of endothelial permeability. However, the entire mechanism of microtubule-dependent regulation of onset and resolution of ALI, and specifically, microtubule-dependent modulation of inflammatory cascades, remains poorly understood. During the screening of potential signaling proteins associated with the microtubules in control and inflamed pulmonary endothelium, we discovered an association of a negative regulator of inflammatory signaling, SOCS1, with the microtubule fraction. This serendipity finding suggested a novel link between the microtubule cytoskeleton and control of endothelial inflammation and inflammation-induced permeability. Currently, a role of microtubules in the modulation of endothelial barrier response to bacterial wall compounds, cytokines, etc., remains virtually unknown. We hypothesize that cellular feedback mechanisms modulating cell inflammatory response critically require microtubule-assisted SOCS1 targeting to the submembrane compartment, where it interacts with its cytokine receptor- and TLR-associated protein targets. Using cell, ex vivo, and in vivo models of LPS-induced ALI this application will characterize regulation of LPS-induced inflammation by SOCS1, investigate involvement of microtubules in control of SOCS1 anti-inflammatory function, and will identify molecular mechanisms of active microtubule-assisted SOCS1 transport and submembrane targeting. The results of this project will delineate novel microtubule-dependent mechanisms regulating lung barrier dysfunction and inflammation, which may lead to discovery of a new group of pharmacological molecules for the treatment of ALI/ARDS.