Hypoxia Triggers AMPK Activation through Reactive Oxygen Species-Mediated Activation of Calcium Release-Activated Calcium Channels
Hypoxia Triggers AMPK Activation through Reactive Oxygen Species-Mediated Activation of Calcium Release-Activated Calcium Channels
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DOI：
10.1128/mcb.05124-11
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发表时间：
2011-09-01
影响因子：
5.3
通讯作者：
Schumacker, Paul T.
中科院分区：
文献类型：
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作者：
Mungai, Paul T.;Waypa, Gregory B.;Schumacker, Paul T.
AMP激活的蛋白激酶（AMPK）是一种能量传感器，通过[AMP]增加或氧化应激（活性氧[ROS]）激活。缺氧增加细胞ROS信号传导，但随后AMPK激活的潜在途径尚不清楚。我们检验了缺氧通过ROS介导的钙释放激活钙通道（CRAC）开放激活AMPK的假设。缺氧（1.5%O（2））增加细胞活性氧，如氧化还原敏感的绿色荧光蛋白（roGFP）检测，但不增加[AMP]/[ATP]比。Fura 2和钙-钙调素荧光共振能量转移（FRET）传感器YC 2.3检测到缺氧期间细胞内钙的增加。抗氧化剂处理或细胞外钙的去除消除缺氧诱导的钙信号和随后的AMPK磷酸化在缺氧期间。氧化应激触发基质相互作用分子1（STIM 1）（内质网（ER）Ca（2+）传感器）重新定位至质膜。通过短干扰RNA（siRNA）敲低STIM 1可减弱钙对缺氧的反应和随后的AMPK磷酸化，而抑制L型钙通道则无影响。通过siRNA敲低AMPK上游激酶LKB 1并不能阻止缺氧期间AMPK的激活，但敲低CaMKK β则会消除AMPK的反应。这些发现表明，缺氧可以在明显缺乏[AMP]增加的情况下通过ROS依赖性CRAC通道激活触发AMPK激活，导致细胞溶质钙增加，从而激活AMPK上游激酶CaMKK β。
AMP-activated protein kinase ( AMPK) is an energy sensor activated by increases in [AMP] or by oxidant stress (reactive oxygen species [ROS]). Hypoxia increases cellular ROS signaling, but the pathways underlying subsequent AMPK activation are not known. We tested the hypothesis that hypoxia activates AMPK by ROS-mediated opening of calcium release-activated calcium (CRAC) channels. Hypoxia (1.5% O(2)) augments cellular ROS as detected by the redox-sensitive green fluorescent protein (roGFP) but does not increase the [AMP]/[ATP] ratio. Increases in intracellular calcium during hypoxia were detected with Fura2 and the calcium-calmodulin fluorescence resonance energy transfer (FRET) sensor YC2.3. Antioxidant treatment or removal of extracellular calcium abrogates hypoxia-induced calcium signaling and subsequent AMPK phosphorylation during hypoxia. Oxidant stress triggers relocation of stromal interaction molecule 1 (STIM1), the endoplasmic reticulum (ER) Ca(2+) sensor, to the plasma membrane. Knockdown of STIM1 by short interfering RNA (siRNA) attenuates the calcium responses to hypoxia and subsequent AMPK phosphorylation, while inhibition of L-type calcium channels has no effect. Knockdown of the AMPK upstream kinase LKB1 by siRNA does not prevent AMPK activation during hypoxia, but knockdown of CaMKK beta abolishes the AMPK response. These findings reveal that hypoxia can trigger AMPK activation in the apparent absence of increased [AMP] through ROS-dependent CRAC channel activation, leading to increases in cytosolic calcium that activate the AMPK upstream kinase CaMKK beta.