Hypoxia-induced endocytosis of Na,K-ATPase in alveolar epithelial cells is mediated by mitochondrial reactive oxygen species and PKC-zeta.
Hypoxia-induced endocytosis of Na,K-ATPase in alveolar epithelial cells is mediated by mitochondrial reactive oxygen species and PKC-zeta.
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DOI：
10.1172/jci16826
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发表时间：
2003-04
期刊：
影响因子：
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通讯作者：
L. Dada;N. Chandel;K. Ridge;C. Pedemonte;A. Bertorello;J. Sznajder
中科院分区：
文献类型：
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作者：
L. Dada;N. Chandel;K. Ridge;C. Pedemonte;A. Bertorello;J. Sznajder
在上升到高海拔和肺水肿期间，肺泡上皮细胞（AEC）暴露于缺氧条件。缺氧抑制肺泡液体重吸收，降低AEC Na，K-ATP酶活性。我们在此报道，AEC暴露于缺氧诱导Na，K-ATP酶活性的时间依赖性降低和基底外侧膜（BLM）上Na，K-ATP酶α（1）亚基数量的平行减少，而不改变其总细胞蛋白丰度。这些影响是可逆的复氧和具体的，因为质膜蛋白GLUT 1没有减少缺氧反应。缺氧引起线粒体活性氧（ROS）水平的增加，抗氧化剂抑制。抗氧化剂阻止了缺氧介导的Na，K-ATP酶活性和BLM蛋白质丰度的降低。缺氧处理的线粒体DNA缺陷AEC（rho（0）细胞）没有增加ROS水平，也没有抑制Na，K-ATP酶活性。缺氧处理的AEC中，Na，K-ATP酶α（1）亚基被PKC磷酸化。在用PKC-zeta拮抗肽或缺少PKC磷酸化位点的Na，K-ATP酶α（1）亚基（Ser-18）处理的AEC中，缺氧不能降低Na，K-ATP酶的丰度和功能。因此，我们提供的证据表明，缺氧通过线粒体ROS和PKC-zeta介导的Na，K-ATP酶α（1）亚基磷酸化触发AEC的内吞作用，从而降低AEC的Na，K-ATP酶活性。
During ascent to high altitude and pulmonary edema, the alveolar epithelial cells (AEC) are exposed to hypoxic conditions. Hypoxia inhibits alveolar fluid reabsorption and decreases Na,K-ATPase activity in AEC. We report here that exposure of AEC to hypoxia induced a time-dependent decrease of Na,K-ATPase activity and a parallel decrease in the number of Na,K-ATPase alpha(1) subunits at the basolateral membrane (BLM), without changing its total cell protein abundance. These effects were reversible upon reoxygenation and specific, because the plasma membrane protein GLUT1 did not decrease in response to hypoxia. Hypoxia caused an increase in mitochondrial reactive oxygen species (ROS) levels that was inhibited by antioxidants. Antioxidants prevented the hypoxia-mediated decrease in Na,K-ATPase activity and protein abundance at the BLM. Hypoxia-treated AEC deficient in mitochondrial DNA (rho(0) cells) did not have increased levels of ROS, nor was the Na,K-ATPase activity inhibited. Na,K-ATPase alpha(1) subunit was phosphorylated by PKC in hypoxia-treated AEC. In AEC treated with a PKC-zeta antagonist peptide or with the Na,K-ATPase alpha(1) subunit lacking the PKC phosphorylation site (Ser-18), hypoxia failed to decrease Na,K-ATPase abundance and function. Accordingly, we provide evidence that hypoxia decreases Na,K-ATPase activity in AEC by triggering its endocytosis through mitochondrial ROS and PKC-zeta-mediated phosphorylation of the Na,K-ATPase alpha(1) subunit.