Sirt3 confers protection against neuronal ischemia by inducing autophagy: Involvement of the AMPK-mTOR pathway
Sirt3 confers protection against neuronal ischemia by inducing autophagy: Involvement of the AMPK-mTOR pathway
复制标题
Sirt3 通过诱导自噬提供针对神经元缺血的保护：AMPK-mTOR 通路的参与
DOI：
10.1016/j.freeradbiomed.2017.04.005
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发表时间：
2017-07-01
影响因子：
7.4
通讯作者：
Jiang, Xiao-Fan
中科院分区：
文献类型：
--
作者：
Dai, Shu-Hui;Chen, Tao;Jiang, Xiao-Fan
Sirtuin3(SIRT3)是线粒体沉默信息调节蛋白2(Sir2)家族的一员，它影响线粒体生物学的几乎所有主要方面，包括ATP的产生和活性氧(ROS)的产生。我们先前的研究表明，SIRT3对神经细胞的氧化应激具有保护作用。在这项研究中，我们利用缺氧缺糖(OGD)模型研究了SIRT3在神经元缺血中的作用。OGD可上调SIRT3的表达，慢病毒介导的SIRT3过表达可显著降低OGD诱导的乳酸脱氢酶(LDH)释放和神经细胞凋亡。伴随这些作用的是减少了过氧化氢(H_2O_2)的产生，增加了ATP的产生，并保留了线粒体膜电位(Mp)。免疫细胞化学和电子显微镜结果显示，SIRT3增加了OGD损伤神经元的自噬，Beclin-1的表达增加以及Lc3-I向Lc3-II的转化也证实了这一点。此外，自噬抑制剂3-MA和巴菲霉素A1部分阻断了SIRT3对OGD后LDH释放和细胞凋亡的影响。Western blotting结果显示，SIRT3在皮层神经元中的过表达显著增加了AMPK的磷酸化，而磷酸化mTOR(p-mTOR)水平在存在和不存在OGD刺激时均降低。此外，AMPK抑制剂化合物C的预处理部分逆转了SIRT3的保护作用。综上所述，这些发现表明，SIRT3通过调节AMPK-mTOR通路诱导自噬来保护OGD损伤，并且SIRT3可能在脑缺血保护神经元方面具有治疗价值。
Sirtuin3 (Sirt3) is a member of the silent information regulator 2 (Sir2) family of proteins located in mitochondria that influences almost every major aspect of mitochondrial biology, including ATP generation and reactive oxygen species (ROS) production. Our previous study showed that Sirt3 exerts protective effects against oxidative stress in neuronal cells. In this study, we investigated the role of Sirt3 in neuronal ischemia using an oxygen and glucose deprivation (OGD) model. Sirt3 was up-regulated by OGD and overexpression of Sirt3 through lentivirus transfection significantly reduced OGD-induced lactate dehydrogenase (LDH) release and neuronal apoptosis. These effects were accompanied by reduced hydrogen dioxide (H2O2) production, enhanced ATP generation and preserved mitochondrial membrane potential (MMP). The results of immunocytochemistry and electron microscopy showed that Sirt3 increased autophagy in OGD-injured neurons, which was also confirmed by the increased expression of Beclin-1 as well as LC3-I to LC3-II conversion. In addition, the autophagy inhibitor 3-MA and bafilomycin A1 partially prevented the effects of Sirt3 on LDH release and apoptosis after OGD. The results of western blotting showed that overexpression of Sirt3 in cortical neurons markedly increased the phosphorylation of AMPK, whereas the phosphor-mTOR (p-mTOR) levels decreased both in the presence and absence of OGD insult. Furthermore, pre-treatment with the AMPK inhibitor compound C partially reversed the protective effects of Sirt3. Taken together, these findings demonstrate that Sirt3 protects against OGD insult by inducing autophagy through regulation of the AMPK-mTOR pathway and that Sirt3 may have therapeutic value for protecting neurons from cerebral ischemia.