Bcl-2 Phosphorylation Triggers Autophagy Switch and Reduces Mitochondrial Damage in Limb Remote Ischemic Conditioned Rats After Ischemic Stroke
Bcl-2 Phosphorylation Triggers Autophagy Switch and Reduces Mitochondrial Damage in Limb Remote Ischemic Conditioned Rats After Ischemic Stroke
复制标题
Bcl-2 磷酸化触发自噬开关并减少缺血性中风后肢体远端缺血大鼠的线粒体损伤
DOI：
10.1007/s12975-015-0393-y
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发表时间：
2015-06-01
影响因子：
6.9
通讯作者：
Luo, Yumin
中科院分区：
文献类型：
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作者：
Qi, Zhifeng;Dong, Wen;Luo, Yumin
自噬是一种重要的细胞内降解途径，已被报道在缺血性疾病中清除受损的线粒体和减少线粒体介导的损伤。我们的研究和最近的其他研究表明，依赖AKT的自噬有助于肢体远程缺血适应(RIC)在实验性卒中中提供神经保护。然而，AKT如何触发基于RIC的自噬以及RIC提供的自噬是否有利于脑缺血后的线粒体功能仍不清楚。有报道称，在丝氨酸70处的Bcl2磷酸化的情况下，Bcl2/Beclin1复合体的破坏会触发自噬的形成。我们利用短暂性脑缺血大鼠模型，研究了Bcl2的磷酸化是否触发了基于RIC的自噬，从而提供了RIC诱导的神经保护，以对抗线粒体损伤。我们发现，在大鼠脑缺血30min(I-30)和再灌流(R-0)时，RIC处理显著上调了Bcl2的磷酸化水平。免疫沉淀显示RIC增加了Bcl2/Beclin1复合体的解离，导致自噬程度高于缺血/再灌流大鼠。此外，AKT激活在调节Bcl2介导的自噬中起关键作用，缺血前30min给予AKT抑制剂(LY294002，Akti)可显著抑制Bcl2的磷酸化和Bcl2/Beclin1复合体的解离，从而减少RIC大鼠的自噬。用Akti阻断Bcl2磷酸化依赖的自噬抑制RIC对线粒体电位和线粒体依赖的细胞死亡效应通路的保护作用。这些结果表明，Bcl2的磷酸化，进而Bcl2/Beclin1复合体的破坏在RIC大鼠脑缺血后触发自噬和减轻线粒体损伤中起着关键作用，需要AKT的激活。
Autophagy, an important intracellular degradation pathway, has been reported to clear impaired mitochondria and reduce mitochondria-mediated injury in ischemic disease. Our study and other recent investigations have shown that AKT-dependent autophagy contributes to the neuroprotection afforded by limb remote ischemic conditioning (RIC) in experimental stroke. However, how AKT triggers RIC-based autophagy and whether RIC-afforded autophagy is beneficial for mitochondrial function after cerebral ischemia remains unclear. The disruption of the Bcl-2/Beclin1 complex has been reported to trigger autophagy formation in the condition of Bcl-2 phosphorylation at Ser70. We investigated whether Bcl-2 phosphorylation triggers RIC-based autophagy and thereby confers RIC-induced neuroprotection against mitochondrial injury, using a transient cerebral ischemic rat model. We demonstrated that rats undergoing RIC treatment 30 min after the onset of ischemia (I-30) and at reperfusion (R-0) significantly upregulated Bcl-2 phosphorylation. Immunoprecipitation revealed that RIC increased dissociation of the Bcl-2/Beclin1 complex, leading to a higher level of autophagy than in ischemia/reperfusion rats. Furthermore, AKT activation was shown to play a critical role in regulating Bcl-2-mediated autophagy, as an AKT inhibitor (LY294002, AKTi) administered 30 min prior to ischemia significantly suppressed Bcl-2 phosphorylation and Bcl-2/Beclin1 complex dissociation, thereby reducing autophagy in RIC rats. Blocking Bcl-2 phosphorylation-dependent autophagy with AKTi suppressed RIC-afforded protection on mitochondrial potential and mitochondrial-dependent cell death effector pathway. These findings indicate that Bcl-2 phosphorylation and thereby Bcl-2/Beclin1 complex disruption play a crucial role in triggering autophagy and reducing mitochondrial damage in RIC rats after cerebral ischemia and require the involvement of the AKT activation.