Pfeil Uwe, Aslam Muhammad, Paddenberg Renate, Quanz Karin, Chang Chia L, Park Jae-Il, Gries Barbara, Rafiq Amir, Faulhammer Petra, Goldenberg Anna, Papadakis Tamara, Noll Thomas, Hsu Sheau Y T, Weissmann Norbert, Kummer Wolfgang
Institute for Anatomy and Cell Biology, Department of Internal Medicine, Justus Liebig University, Aulweg 123, 35385 Giessen, Germany.
Am J Physiol Lung Cell Mol Physiol. 2009 Nov;297(5):L837-45. doi: 10.1152/ajplung.90608.2008. Epub 2009 Aug 14.
Accumulating evidence suggests a pivotal role of the calcitonin receptor-like receptor (CRLR) signaling pathway in preventing damage of the lung by stabilizing pulmonary barrier function. Intermedin (IMD), also termed adrenomedullin-2, is the most recently identified peptide targeting this receptor. Here we investigated the effect of hypoxia on the expression of IMD in the murine lung and cultured murine pulmonary microvascular endothelial cells (PMEC) as well as the role of IMD in regulating vascular permeability. Monoclonal IMD antibodies were generated, and transcript levels were assayed by quantitative RT-PCR. The promoter region of IMD gene was analyzed, and the effect of hypoxia-inducible factor (HIF)-1alpha on IMD expression was investigated in HEK293T cells. Isolated murine lungs and a human lung microvascular endothelial cell monolayer model were used to study the effect of IMD on vascular permeability. IMD was identified as a pulmonary endothelial peptide by immunohistochemistry and RT-PCR. Hypoxia caused an upregulation of IMD mRNA in the murine lung and PMEC. As shown by these results, HIF-1alpha enhances IMD promoter activity. Our functional studies showed that IMD abolished the increase in pressure-induced endothelial permeability. Moreover, IMD decreased basal and thrombin-induced hyperpermeability of an endothelial cell monolayer in a receptor-dependent manner and activated PKA in these cells. In conclusion, IMD is a novel hypoxia-induced gene and a potential interventional agent for the improvement of endothelial barrier function in systemic inflammatory responses and hypoxia-induced vascular leakage.
越来越多的证据表明，降钙素受体样受体（CRLR）信号通路在通过稳定肺屏障功能来预防肺损伤方面起着关键作用。中介素（IMD），也称为肾上腺髓质素-2，是最近发现的靶向该受体的肽。在此，我们研究了缺氧对小鼠肺组织和培养的小鼠肺微血管内皮细胞（PMEC）中IMD表达的影响，以及IMD在调节血管通透性中的作用。制备了单克隆IMD抗体，并通过定量RT-PCR测定转录水平。分析了IMD基因的启动子区域，并在HEK293T细胞中研究了缺氧诱导因子（HIF）-1α对IMD表达的影响。使用分离的小鼠肺组织和人肺微血管内皮细胞单层模型来研究IMD对血管通透性的影响。通过免疫组织化学和RT-PCR鉴定IMD为肺内皮肽。缺氧导致小鼠肺组织和PMEC中IMD mRNA上调。如这些结果所示，HIF-1α增强IMD启动子活性。我们的功能研究表明，IMD消除了压力诱导的内皮通透性增加。此外，IMD以受体依赖性方式降低内皮细胞单层的基础和凝血酶诱导的高通透性，并在这些细胞中激活PKA。总之，IMD是一种新型的缺氧诱导基因，是改善全身炎症反应和缺氧诱导的血管渗漏中内皮屏障功能的潜在干预剂。
