Hypoxia-induced cytoskeleton disruption in alveolar epithelial cells
Hypoxia-induced cytoskeleton disruption in alveolar epithelial cells
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DOI：
10.1165/rcmb.2005-0478oc
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发表时间：
2006-11-01
影响因子：
6.4
通讯作者：
Clerici, Christine
中科院分区：
文献类型：
--
作者：
Bouvry, Diane;Planes, Carole;Clerici, Christine
肺泡缺氧是许多呼吸系统疾病的一个常见特征，此前已报道可引起功能变化，特别是跨上皮钠和液体转运的减少。在极化上皮中，细胞骨架在离子和液体的跨细胞和旁细胞运输中发挥调节作用。我们假设暴露于缺氧可能会损害细胞骨架组织，进而可能对离子和液体运输产生不利影响。原代大鼠肺泡上皮细胞（AEC）暴露于轻度（3％O-2）或重度（0.5％O-2）缺氧18小时或常氧（21％O-2）。首先，轻度和重度缺氧会引起肌动蛋白（细胞骨架的主要蛋白质）的紊乱，表现为 F-肌动蛋白丝的破坏。其次，α-血影蛋白是一种顶端细胞骨架蛋白，与肌动蛋白细胞骨架和Na转运蛋白结合，在缺氧时被裂解。用半胱天冬酶抑制剂（z-VAD-fmk；90 μM）对 AEC 进行预处理，可减弱缺氧诱导的血影蛋白裂解以及缺氧诱导的表面膜 α-ENaC 减少，同时诱导缺氧导致的阿米洛利敏感性 Na 转运减少在 3% O-2 下部分恢复。最后，紧密连接（TJ）蛋白与肌动蛋白相连，是细胞旁通透性的决定因素，会因轻度和重度缺氧而改变：缺氧导致 Occludin 从 TJ 错误定位到细胞质，并导致 zonula occlusionns-1 蛋白水平下降。这些修饰与 0.5% O-2 时细胞旁通透性的适度变化相关，通过小 4-kD 葡聚糖通量和跨上皮阻力测量进行评估。总之，这些发现表明缺氧破坏了 AEC 中的细胞骨架和 TJ 组织，并且可能至少部分参与缺氧引起的 Na 转运减少。
Alveolar hypoxia, a common feature of many respiratory disorders, has been previously reported to induce functional changes, particularly a decrease of transepithelial Na and fluid transport. In polarized epithelia, cytoskeleton plays a regulatory role in transcellular and paracellular transport of ions and fluid. We hypothesized that exposure to hypoxia could damage cytoskeleton organization, which in turn, may adversely affect ion and fluid transport. Primary rat alveolar epithelial cells (AEC) were exposed to either mild (3% O-2) or severe (0.5% O-2) hypoxia for 18 h or to normoxia (21% O-2). First, mild and severe hypoxia induced a disorganization of actin, a major protein of the cytoskeleton, reflected by disruption of F-actin filaments. Second, alpha-spectrin, an apical cytoskeleton protein, which binds to actin cytoskeleton and Na transport proteins, was cleaved by hypoxia. Pretreatment of AEC by a caspase inhibitor (z-VAD-fmk; 90 mu M) blunted hypoxia-induced spectrin cleavage as well as hypoxia-induced decrease in surface membrane alpha-ENaC and concomitantly induced a partial recovery of hypoxia-incluced decrease of amiloride-sensitive Na transport at 3% O-2. Finally, tight junctions (TJs) proteins, which are linked to actin and are a determinant of paracellular permeability, were altered by mild and severe hypoxia: hypoxia induced a mislocalization of occludin from the TJ to cytoplasm and a decrease in zonula occludens-1 protein level. These modifications were associated with modest changes in paracellular permeability at 0.5% O-2, as assessed by small 4-kD dextran flux and transepithelial resistance measurements. Together, these findings indicate that hypoxia disrupted cytoskeleton and TJ organization in AEC and may participate, at least in part, to hypoxia-induced decrease in Na transport.