Milovanova Tatyana, Chatterjee Shampa, Hawkins Brian J, Hong Nankang, Sorokina Elena M, Debolt Kris, Moore Jonni S, Madesh Muniswamy, Fisher Aron B
Institute For Environmental Medicine, University of Pennsylvania Medical Center, One John Morgan Building, Philadelphia, PA 19104-6068, USA.
Biochim Biophys Acta. 2008 Oct;1783(10):1866-75. doi: 10.1016/j.bbamcr.2008.05.010. Epub 2008 May 23.
Abrupt cessation of flow representing the acute loss of shear stress (simulated ischemia) to flow-adapted pulmonary microvascular endothelial cells (PMVEC) leads to reactive oxygen species (ROS) generation that signals for EC proliferation. We evaluated the role of caveolin-1 on this cellular response with mouse PMVEC that were preconditioned for 72 h to laminar flow at 5 dyn/cm(2) followed by stop of flow ("ischemia"). Preconditioning resulted in a 2.7-fold increase in cellular expression of K(ATP) (K(IR) 6.2) channels but no change in expression level of caveolin-1, gp91(phox), or MAP kinases. The initial response to ischemia in wild type cells was cell membrane depolarization that was abolished by gene targeting of K(IR) 6.2. The subsequent response was increased ROS production associated with activation of NADPH oxidase (NOX2) and then phosphorylation of MAP kinases (Erk, JNK). After 24 h of ischemia in wild type cells, the cell proliferation index increased 2.5 fold and the % of cells in S+G(2)/M phases increased 6-fold. This signaling cascade (cell membrane depolarization, ROS production, MAP kinase activation and cell proliferation) was abrogated in caveolin-1 null PMVEC or by treatment of wild type cells with filipin. These studies indicate that caveolin-1 functions as a shear sensor in flow-adapted EC resulting in ROS-mediated cell signaling and endothelial cell proliferation following the abrupt reduction in flow.
血流突然停止代表血流适应型肺微血管内皮细胞（PMVEC）所受剪切应力的急性丧失（模拟缺血），会导致活性氧（ROS）生成，进而发出内皮细胞增殖的信号。我们利用小鼠PMVEC评估了小窝蛋白-1在此细胞反应中的作用，这些细胞预先在5达因/平方厘米的层流条件下培养72小时，随后停止血流（“缺血”）。预处理使细胞K（ATP）（K（IR）6.2）通道的表达增加了2.7倍，但小窝蛋白-1、gp91（phox）或丝裂原活化蛋白激酶的表达水平没有变化。野生型细胞对缺血的初始反应是细胞膜去极化，而通过K（IR）6.2基因靶向可消除这种去极化。随后的反应是ROS生成增加，这与NADPH氧化酶（NOX2）的激活以及丝裂原活化蛋白激酶（Erk、JNK）的磷酸化有关。野生型细胞缺血24小时后，细胞增殖指数增加了2.5倍，处于S+G（2）/M期的细胞百分比增加了6倍。在小窝蛋白-1缺失的PMVEC中或用制霉菌素处理野生型细胞后，这种信号级联反应（细胞膜去极化、ROS生成、丝裂原活化蛋白激酶激活和细胞增殖）被消除。这些研究表明，小窝蛋白-1在血流适应型内皮细胞中作为剪切传感器发挥作用，导致血流突然减少后ROS介导的细胞信号传导和内皮细胞增殖。
