Endothelial Akt activation by hyperoxia: Role in cell survival
Endothelial Akt activation by hyperoxia: Role in cell survival
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DOI：
10.1016/j.freeradbiomed.2005.10.045
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发表时间：
2006-04-01
影响因子：
7.4
通讯作者：
White，CW
中科院分区：
文献类型：
--
作者：
Ahmad，A;Ahmad，S;White，CW
早产儿和重症患者治疗中经常需要高氧浓度（高氧），这会导致肺损伤，尤其是内皮损伤。暴露原代人肺微血管内皮细胞（HLMVEC）高氧引起短暂的Akt激活后60分钟，磷酸化的丝氨酸473 Akt蛋白质印迹分析确定。Akt磷酸化在高氧暴露24 h后也增加，在48 h时下降。腺病毒（Ad）介导的组成型活性myrAkt的表达保护HLMVEC免受高氧损伤。由于高氧（95%O2，8天），这主要是坏死的细胞死亡，是大量的控制和Ad-LacZ转导的细胞，但减少了几乎一半myrAkt转导的细胞。高氧导致细胞葡萄糖消耗增加，与LacZ转导或非转导对照相比，在用myrAkt转导的细胞中放大的效果。myrAkt表达细胞中葡萄糖消耗的增加伴随着mTOR和p70 S6-激酶磷酸化的增加。雷帕霉素处理降低myrAkt转导细胞中的葡萄糖消耗至与暴露于高氧的对照和LacZ转导细胞中的葡萄糖消耗相当的水平。超微结构形态分析表明，线粒体和内质网肿胀myrAkt细胞相对于对照暴露于高氧。这些研究表明，Akt的早期激活发生在HLMVEC高氧。Akt的组成性激活至少部分地通过维持线粒体完整性来保护免受高氧应激，这一发现表明该事件是有益的应答。
High oxygen concentrations (hyperoxia), often required in the treatment of preterm infants and critically ill patients, cause lung injury, targeting especially the endothelium. Exposure of primary human lung microvascular endothelial cells (HLMVEC) to hyperoxia caused transient Akt activation after 60 min, as determined by Western blot analysis of phosphorylated Ser 473 of Akt. Akt phosphorylation was also increased after 24 h of hyperoxic exposure, which declined at 48 h. Adenoviral (Ad)-mediated expression of constitutively active myrAkt protected HLMVEC against hyperoxic injury. Cell death due to hyperoxia (95% O2, 8 days), which was primarily necrotic, was substantial in control and Ad-LacZ-transduced cells, but was diminished by almost half in myrAkt-transduced cells. Hyperoxia caused increased cellular glucose consumption, an effect that was amplified in cells transduced with myrAkt compared to the LacZ-transduced or the nontransduced controls. Increased glucose consumption in myrAkt-expressing cells was accompanied by increased phosphorylation of mTOR and p70 S6-kinase. Rapamycin treatment decreased glucose consumption in myrAkt-transduced cells to levels comparable to those in control and LacZ-transduced cells exposed to hyperoxia. Ultrastructural morphometric analyses demonstrated that mitochondria and endoplasmic reticulum were less swollen in myrAkt cells relative to controls exposed to hyperoxia. These studies demonstrate that early activation of Akt occurs in hyperoxia in HLMVEC. That this event is a beneficial response is suggested by the finding that constitutive activation of Akt protects against hyperoxic stress, at least in part, by maintaining mitochondrial integrity.