title: Sirt3 confers protection against neuronal ischemia by inducing autophagy: Involvement of the AMPK-mTOR pathway.
abstract: 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.
authors.affiliation: Department of Neurosurgery, Xijing Institute of Clinical Neuroscience, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi 710032, China.
authors.forename: Shu-Hui
authors.initials: SH
authors.lastname: Dai
authors.affiliation: Department of Neurosurgery, Xijing Institute of Clinical Neuroscience, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi 710032, China; Department of Neurosurgery, The 101th Hospital of PLA, Rescue Center of Craniocerebral Injuries of PLA, Wuxi, Jiangsu 214044, China; Department of Neurosurgery, The 123th Hospital of PLA, Bengbu, Anhui 233000, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Chen
authors.affiliation: Department of Neurosurgery, Xijing Institute of Clinical Neuroscience, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi 710032, China.
authors.forename: Xia
authors.initials: X
authors.lastname: Li
authors.affiliation: Department of Neurosurgery, Xijing Institute of Clinical Neuroscience, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi 710032, China.
authors.forename: Kang-Yi
authors.initials: KY
authors.lastname: Yue
authors.affiliation: Department of Neurosurgery, Xijing Institute of Clinical Neuroscience, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi 710032, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Luo
authors.affiliation: Department of Neurosurgery, The 101th Hospital of PLA, Rescue Center of Craniocerebral Injuries of PLA, Wuxi, Jiangsu 214044, China.
authors.forename: Li-Kun
authors.initials: LK
authors.lastname: Yang
authors.affiliation: Department of Neurosurgery, The 101th Hospital of PLA, Rescue Center of Craniocerebral Injuries of PLA, Wuxi, Jiangsu 214044, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhu
authors.affiliation: Department of Neurosurgery, The 101th Hospital of PLA, Rescue Center of Craniocerebral Injuries of PLA, Wuxi, Jiangsu 214044, China.
authors.forename: Yu-Hai
authors.initials: YH
authors.lastname: Wang
authors.affiliation: Department of Neurosurgery, Xijing Institute of Clinical Neuroscience, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi 710032, China. Electronic address: fmmuzhoufei@163.com.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Fei
authors.affiliation: Department of Neurosurgery, Xijing Institute of Clinical Neuroscience, Xijing Hospital, Fourth Military Medical University, Xi'an, Shaanxi 710032, China. Electronic address: fmmujiangxiaofan@163.com.
authors.forename: Xiao-Fan
authors.initials: XF
authors.lastname: Jiang
mesh_terms: D000263:Adenylate Kinase / Q000378:metabolism; D000818:Animals; D001343:Autophagy; D000071186:Beclin-1 / Q000235:genetics / Q000378:metabolism; D002545:Brain Ischemia / Q000378:metabolism*; D002478:Cells, Cultured; D005947:Glucose / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial; D008928:Mitochondria / Q000502:physiology*; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D018384:Oxidative Stress; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction; D056566:Sirtuin 3 / Q000235:genetics / Q000378:metabolism*; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D015854:Up-Regulation
chemical_list: D000071186:Beclin-1; D006861:Hydrogen Peroxide; C546845:mTOR protein, rat; D058570:TOR Serine-Threonine Kinases; D000263:Adenylate Kinase; D056566:Sirtuin 3; D005947:Glucose
keywords: AMPK; Autophagy; Ischemic stroke; Sirt3; mTOR