University Hospitals Harrington-McLaughlin Heart and Vascular Institute and Case Cardiovascular Research Institute, Cleveland, OH 44106-7290, USA.
Arterioscler Thromb Vasc Biol. 2010 Oct;30(10):1952-9. doi: 10.1161/ATVBAHA.110.211474. Epub 2010 Jul 22.
A central function of the endothelium is to serve as a selective barrier that regulates fluid and solute exchange. Although perturbation of barrier function can contribute to numerous disease states, our understanding of the molecular mechanisms regulating this aspect of endothelial biology remains incompletely understood. Accumulating evidence implicates the Kruppel-like factor 2 (KLF2) as a key regulator of endothelial function. However, its role in vascular barrier function is unknown.
To assess the role of KLF2 in vascular barrier function in vivo, we measured the leakage of Evans blue dye into interstitial tissues of the mouse ear after treatment with mustard oil. By comparison with KLF2(+/+) mice, KLF2(+/-) mice exhibited a significantly higher degree of vascular leak. In accordance with our in vivo observation, adenoviral overexpression of KLF2 in human umbilical vein endothelial cells strongly attenuated the increase of endothelial leakage by thrombin and H(2)O(2) as measured by fluorescein isothiocyanate dextrans (FITC-dextran) passage. Conversely, KLF2 deficiency in human umbilical vein endothelial cells and primary endothelial cells derived from KLF2(+/-) mice exhibited a marked increase in thrombin and H(2)O(2)-induced permeability. Mechanistically, our studies indicate that KLF2 confers barrier-protection via differential effects on the expression of key junction protein occludin and modification of a signaling molecule (myosin light chain) that regulate endothelial barrier integrity.
These observations identify KLF2 as a novel transcriptional regulator of vascular barrier function.
内皮细胞的一个主要功能是作为选择性屏障，调节液体和溶质交换。尽管屏障功能的破坏可能导致许多疾病状态，但我们对调节内皮生物学这一方面的分子机制的理解仍不完整。越来越多的证据表明，Kruppel 样因子 2（KLF2）是内皮功能的关键调节因子。然而，其在血管屏障功能中的作用尚不清楚。
为了评估 KLF2 在血管屏障功能中的体内作用，我们测量了芥子油处理后小鼠耳间质组织中 Evans 蓝染料的渗漏。与 KLF2(+/+)小鼠相比，KLF2(+/-)小鼠表现出更高程度的血管渗漏。与我们的体内观察一致，腺病毒过表达 KLF2 可强烈减弱凝血酶和 H2O2 引起的人脐静脉内皮细胞通透性增加，如荧光素异硫氰酸酯葡聚糖（FITC-葡聚糖）通过量测量所示。相反，KLF2 在人脐静脉内皮细胞和源自 KLF2(+/-)小鼠的原代内皮细胞中的缺失导致凝血酶和 H2O2 诱导的通透性显著增加。从机制上讲，我们的研究表明，KLF2 通过对关键连接蛋白闭合蛋白的表达产生差异影响，并调节内皮屏障完整性的信号分子（肌球蛋白轻链）来发挥屏障保护作用。
这些观察结果表明 KLF2 是血管屏障功能的新型转录调节因子。
