Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, MD9, Singapore, 117597, Singapore.
Neurobiology/Ageing Programme, Life Sciences Institute, National University of Singapore, Singapore, 117456, Singapore.
Mol Neurobiol. 2018 Dec;55(12):9188-9203. doi: 10.1007/s12035-018-1058-0. Epub 2018 Apr 14.
Sirtuin 2 (SIRT2) is a family member of nicotinamide adenine dinucleotide (NAD)-dependent deacetylases which appears to have detrimental roles in an array of neurological disorders such as Parkinson's disease (PD) and Huntington's disease (HD). In light of the recently emerging roles of sirtuins in normal physiology and pathological conditions such as ischemic stroke, we investigated the role of SIRT2 in ischemic stroke-induced neuronal cell death. Primary cortical neurons were subjected to oxygen-glucose deprivation (OGD) under in vitro ischemic conditions, and subsequently tested for the efficacy of SIRT2 inhibitors AK1 and AGK2 in attenuating apoptotic cell death caused by OGD. We have also evaluated the effect of SIRT2 inhibition in C57BL/6 mice subjected to 1 h middle cerebral artery occlusion (MCAO) followed by 24 h reperfusion, which is a model for ischemic reperfusion injury in vivo. Significant reductions in apoptotic cell death were noted in neurons treated with AK1 or AGK2, as evidenced by reduced cleaved caspase-3 and other apoptotic markers such as Bim and Bad. In addition, downregulation of phosphorylated-AKT and FOXO3a proteins of the AKT/FOXO3a pathway, as well as a marked reduction of JNK activity and its downstream target c-Jun, were also observed. When tested in animals subjected to MCAO, the neuroprotective effects of AGK2 in vivo were evidenced by a substantial reduction in ipsilateral infarct area and a significant improvement in neurological outcomes. A similar reduction in the levels of pro-apoptotic proteins in the infarct tissue, as well as downregulation of AKT/FOXO3a and JNK pathway, were also noted. In summary, the current study demonstrated the neuroprotective effects of SIRT2 inhibition in ischemic stroke, and identified the downregulation of AKT/FOXO3a and MAPK pathways as intermediary mechanisms which may contribute to the reduction in apoptotic cell death by SIRT2 inhibition.
Sirtuin 2 (SIRT2) 是烟酰胺腺嘌呤二核苷酸 (NAD)-依赖性去乙酰化酶家族的一员，它在一系列神经退行性疾病中似乎具有有害作用，如帕金森病 (PD) 和亨廷顿病 (HD)。鉴于 Sirtuins 在正常生理和病理条件下的作用（如缺血性中风）最近出现，我们研究了 SIRT2 在缺血性中风诱导的神经元细胞死亡中的作用。原代皮质神经元在体外缺血条件下进行氧葡萄糖剥夺 (OGD)，然后测试 SIRT2 抑制剂 AK1 和 AGK2 减轻 OGD 引起的细胞凋亡的效果。我们还评估了 SIRT2 抑制在 C57BL/6 小鼠中的作用，该小鼠接受 1 小时大脑中动脉闭塞 (MCAO) 后再灌注 24 小时，这是体内缺血再灌注损伤的模型。AK1 或 AGK2 处理的神经元中凋亡细胞死亡明显减少，这表明 cleaved caspase-3 和其他凋亡标志物（如 Bim 和 Bad）减少。此外，AKT/FOXO3a 通路的磷酸化-AKT 和 FOXO3a 蛋白下调，以及 JNK 活性及其下游靶标 c-Jun 的明显减少也观察到。在接受 MCAO 的动物中进行测试时，AGK2 在体内的神经保护作用表现为同侧梗死面积的显著减少和神经功能结局的显著改善。梗死组织中促凋亡蛋白水平的类似降低，以及 AKT/FOXO3a 和 JNK 通路的下调也观察到。总之，本研究证明了 SIRT2 抑制在缺血性中风中的神经保护作用，并确定了 AKT/FOXO3a 和 MAPK 通路的下调是 SIRT2 抑制减少细胞凋亡的中介机制。
