Meliton Angelo, Meng Fanyong, Tian Yufeng, Shah Alok A, Birukova Anna A, Birukov Konstantin G
Lung Injury Center and Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, Chicago, Illinois.
Am J Respir Cell Mol Biol. 2015 Dec;53(6):834-43. doi: 10.1165/rcmb.2014-0376OC.
Mechanisms of vascular endothelial cell (EC) barrier regulation during acute lung injury (ALI) or other pathologies associated with increased vascular leakiness are an active area of research. Adaptor protein krev interaction trapped-1 (KRIT1) participates in angiogenesis, lumen formation, and stabilization of EC adherens junctions (AJs) in mature vasculature. We tested a role of KRIT1 in the regulation of Rho-GTPase signaling induced by mechanical stimulation and barrier dysfunction relevant to ventilator-induced lung injury and investigated KRIT1 involvement in EC barrier protection by prostacyclin (PC). PC stimulated Ras-related protein 1 (Rap1)-dependent association of KRIT1 with vascular endothelial cadherin at AJs, with KRIT1-dependent cortical cytoskeletal remodeling leading to EC barrier enhancement. KRIT1 knockdown exacerbated Rho-GTPase activation and EC barrier disruption induced by pathologic 18% cyclic stretch and thrombin receptor activating peptide (TRAP) 6 and attenuated the protective effects of PC. In the two-hit model of ALI caused by high tidal volume (HTV) mechanical ventilation and TRAP6 injection, KRIT1 functional deficiency in KRIT1(+/-) mice increased basal lung vascular leak and augmented vascular leak and lung injury caused by exposure to HTV and TRAP6. Down-regulation of KRIT1 also diminished the protective effects of PC against TRAP6/HTV-induced lung injury. These results demonstrate a KRIT1-dependent mechanism of vascular EC barrier control in basal conditions and in the two-hit model of ALI caused by excessive mechanical forces and TRAP6 via negative regulation of Rho activity and enhancement of cell junctions. We also conclude that the stimulation of the Rap1-KRIT1 signaling module is a major mechanism of vascular endothelial barrier protection by PC in the injured lung.
急性肺损伤（ALI）或其他与血管通透性增加相关的病理过程中，血管内皮细胞（EC）屏障调节机制是一个活跃的研究领域。衔接蛋白krev相互作用捕获蛋白1（KRIT1）参与成熟血管生成、管腔形成以及EC黏附连接（AJs）的稳定。我们测试了KRIT1在机械刺激和与呼吸机诱导性肺损伤相关的屏障功能障碍所诱导的Rho-GTPase信号调节中的作用，并研究了KRIT1在前列环素（PC）对EC屏障保护中的参与情况。PC刺激Rap1依赖的KRIT1与AJs处血管内皮钙黏蛋白的结合，KRIT1依赖的皮质细胞骨架重塑导致EC屏障增强。KRIT1敲低加剧了由病理性18%循环拉伸和凝血酶受体激活肽（TRAP）6诱导的Rho-GTPase激活和EC屏障破坏，并减弱了PC的保护作用。在高潮气量（HTV）机械通气和TRAP6注射引起的ALI双打击模型中，KRIT1(+/-)小鼠中KRIT1功能缺陷增加了基础肺血管渗漏，并加剧了暴露于HTV和TRAP6所导致的血管渗漏和肺损伤。KRIT1的下调也减弱了PC对TRAP6/HTV诱导的肺损伤的保护作用。这些结果表明，在基础条件下以及在由过度机械力和TRAP6引起的ALI双打击模型中，通过对Rho活性的负调节和细胞连接的增强，存在一种依赖KRIT1的血管EC屏障控制机制。我们还得出结论，Rap1-KRIT1信号模块的刺激是PC在损伤肺中保护血管内皮屏障的主要机制。
