Microvascular hyperpermeability in caveolin-1 (-/-) knock-out mice - Treatment with a specific nitric-oxide synthase inhibitor, L-name, restores normal microvascular permeability in Cav-1 null mice
Microvascular hyperpermeability in caveolin-1 (-/-) knock-out mice - Treatment with a specific nitric-oxide synthase inhibitor, L-name, restores normal microvascular permeability in Cav-1 null mice
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DOI：
10.1074/jbc.m205948200
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发表时间：
2002-10-18
影响因子：
4.8
通讯作者：
Lisanti, MP
中科院分区：
文献类型：
--
作者：
Schubert, W;Frank, PG;Lisanti, MP
微血管通透性由跨内皮细胞的分子胞穴转胞吞作用和 (ii) 离子和营养物质的细胞旁运动介导。最近，我们使用标准同源重组技术衍生了 Cav-1 (-/-) 敲除小鼠。这些小鼠可以存活，但表现出内皮细胞小凹的丧失以及小凹介导的内吞作用的显着缺陷。因此，补偿机制必须在这些小鼠中发挥作用。一种可能的代偿反应是细胞旁通路的增加，导致微血管通透性增加。为了直接检验这一假设，我们使用多种互补的体内方法研究了 Cav-1 缺失小鼠的微血管通透性。将放射性碘化牛血清白蛋白注射到 Cav-1 缺陷小鼠中，并将其从循环系统中的清除率与野生型对照小鼠进行比较。我们的结果表明，碘化牛血清白蛋白以更快的速度从 Cav-1 缺陷小鼠的循环系统中清除。为了确定这种缺陷是否仅限于白蛋白的细胞旁运动，接下来用电子致密染料钌红灌注 Cav-1 缺陷小鼠的肺部。 Cav-1 缺陷小鼠肺内皮细胞的显微照片表明，钌红的细胞旁运动显着增加。此外，Cav-1缺陷型肺毛细血管的电子显微照片揭示了紧密连接形态的缺陷以及毛细血管内皮细胞与基底膜粘附的异常。这种细胞-基质附着缺陷与 Caveolin-1 在正向调节整合素信号传导中的假定作用一致。由于caveolin-1表达的丧失会导致eNOS活性的组成性激活，因此我们还检查了微血管通透性的增加是否依赖于NO。有趣的是，L-NAME（一种成熟的一氧化氮合酶抑制剂）治疗成功逆转了 Cav-1 敲除小鼠的微血管通透性过高表型。因此，caveolin-1 在控制微血管通透性方面发挥双重调节作用：(i) 作为小凹形成和小凹转胞吞作用所需的结构蛋白；(ii) 作为 eNOS 活性的强直抑制剂，以负向调节细胞旁途径。
Microvascular permeability is mediated by W the caveolar transcytosis of molecules across endothelial cells and (ii) the paracellular movement of ions and nutrients. Recently, we derived Cav-1 (-/-) knock-out mice using standard homologous recombination techniques. These mice are viable but show a loss of endothelial cell caveolae and striking defects in caveolae-mediated endocytosis. Thus, a compensatory mechanism must be operating in these mice. One possible compensatory response would be an increase in the paracellular pathway, resulting in increased microvascular permeability. To test this hypothesis directly, we studied the microvascular permeability of Cav-1 null mice using a variety of complementary in vivo approaches. Radio-iodinated bovine serum albumin was injected into Cav-1-deficient mice, and its rate of clearance from the circulatory system was compared with that of wild type control mice. Our results indicate that iodinated bovine serum albumin is removed from the circulatory system of Cav-1-deficient mice at a substantially faster rate. To determine whether this defect is restricted to the paracellular movement of albumin, lungs from Cav-1-deficient mice were next perfused with the electron dense dye Ruthenium Red. Micrographs of lung endothelial cells from Cav-1-deficient mice demonstrate that the paracellular movement of Ruthenium Red is dramatically increased. In addition, electron micrographs of Cav-1-deficient lung capillaries reveal defects in tight junction morphology and abnormalities in capillary endothelial cell adhesion to the basement membrane. This defect in cell-substrate attachment is consistent with the postulated role of caveolin-1 in positively regulating integrin signaling. Because loss of caveolin-1 expression results in constitutive activation of eNOS activity, we also examined whether these increases in microvascular permeability are NO-dependent. Interestingly, treatment with L-NAME (a well established nitric-oxide synthase inhibitor) successfully reversed the microvascular hyperpermeability phenotype of Cav-1 knock-out mice. Thus, caveolin-1 plays a dual regulatory role in controlling microvascular permeability: (i) as a structural protein that is required for caveolae formation and caveolar transcytosis and (ii) as a tonic inhibitor of eNOS activity to negatively regulate the paracellular pathway.