Thioredoxin-deficient mice, a novel phenotype sensitive to ambient air and hypersensitive to hyperoxia-induced lung injury
Thioredoxin-deficient mice, a novel phenotype sensitive to ambient air and hypersensitive to hyperoxia-induced lung injury
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DOI：
10.1152/ajplung.00285.2014
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发表时间：
2015-03-01
影响因子：
4.9
通讯作者：
Das, Kumuda C.
中科院分区：
文献类型：
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作者：
Das, Kumuda C.
肺氧中毒是接受辅助供氧治疗的患者的主要临床问题。硫氧还蛋白（Trx）是一种内源性抗氧化蛋白，可使氧化失活的蛋白质再生。我们研究了Trx如何有助于氧耐受性，通过创建转基因小鼠的功能性硫氧还蛋白（dnTrx-Tg）的水平降低，使用显性负性的方法。这些小鼠在肺中显示出降低的Trx活性，尽管突变蛋白的表达比野生型小鼠高三倍。此外，我们发现这些小鼠在室内空气中内源性Trx的氧化增加。当暴露于高氧（> 90%O-2）4天后，它们无法恢复，并显示出显著的死亡率。即使在正常的氧水平下，这些小鼠也显示出乌头酸酶和NADH脱氢酶活性的显著降低，线粒体能量代谢降低，p53和Gadd 45 α表达增加，促炎细胞因子的合成增加。这些影响进一步增加高氧。我们还产生了过表达Trx（Trx-Tg）的小鼠，发现它们在暴露于高氧期间保持肺氧化还原平衡，因此对高氧诱导的肺损伤具有抗性。这些小鼠在常氧和高氧下肺中还原Trx水平增加。此外，乌头酸酶和NADH脱氢酶活性的水平在这些小鼠中维持伴随着线粒体能量代谢的维持。与dnTrx-Tg或野生型小鼠相比，基因毒性应激标志物如p53或Gadd 45 α在高氧下保持在显著较低的水平。这些研究证实，功能性Trx缺陷的小鼠表现出对环境空气敏感和对高氧超敏的表型。
Pulmonary oxygen toxicity is a major clinical problem for patients undergoing supplemental oxygen therapy. Thioredoxin (Trx) is an endogenous antioxidant protein that regenerates oxidatively inactivated proteins. We examined how Trx contributes to oxygen tolerance by creating transgenic mice with decreased levels of functional thioredoxin (dnTrx-Tg) using a dominant-negative approach. These mice showed decreased Trx activity in the lung although the expression of mutant protein is three times higher than the wild-type mice. Additionally, we found that these mice showed increased oxidation of endogenous Trx in room air. When exposed to hyperoxia (>90% O-2) for 4 days, they failed to recover and showed significant mortality. Even in normal oxygen levels, these mice displayed a significant decrease in aconitase and NADH dehydrogenase activities, decreased mitochondrial energy metabolism, increased p53 and Gadd45 alpha expression, and increased synthesis of proinflammatory cytokines. These effects were further increased by hyperoxia. We also generated mice overexpressing Trx (Trx-Tg) and found they maintained lung redox balance during exposure to high oxygen and thus were resistant to hyperoxia-induced lung injury. These mice had increased levels of reduced Trx in the lung in normoxia as well as hyperoxia. Furthermore, the levels of aconitase and NADH dehydrogenase activities were maintained in these mice concomitant with maintenance of mitochondrial energy metabolism. The genotoxic stress markers such as p53 or Gadd45 alpha remained in significantly lower levels in hyperoxia compared with dnTrx-Tg or wild-type mice. These studies establish that mice deficient in functional Trx exhibit a phenotype of sensitivity to ambient air and hypersensitivity to hyperoxia.