Institute of Brain Science, National Yang Ming Chiao Tung University, Taipei City, 112, Taiwan; Institute of Brain Science, National Yang-Ming University, Taipei City, 112, Taiwan.
Department of Neurology, College of Medicine, Kaohsiung Medical University, Kaohsiung City, 807, Taiwan; Department of Neurology, Kaohsiung Medical University Hospital, Kaohsiung City, 807, Taiwan.
Free Radic Biol Med. 2021 Jun;169:36-61. doi: 10.1016/j.freeradbiomed.2021.04.004. Epub 2021 Apr 17.
Accumulation of senile plaques mainly composed of neurotoxic amyloid-beta peptide (Aβ) is a pathological hallmark of Alzheimer's disease (AD). Sestrin2 inducible by various types of stressors is known to promote autophagy and exert antioxidative effects. In this work, we revealed the molecular mechanisms underlying Aβ induction of sestrin2 and tested whether antioxidation, in addition to autophagy regulation, also contributes to its neuroprotective effects in primary rat cortical neurons. We found that Aβ25-35 triggered nuclear translocation of p65 and p50, two subunits of nuclear factor-kappaB (NF-κB), and p53. Aβ25-35-induced sestrin2 expression was abolished by the p65 siRNA, the NF-κB inhibitor SN50, and the p53 inhibitor pifithrin-alpha (PFT-α). Further, Aβ25-35 enhanced binding of p50 and p53 to sestrin2 gene promoter that was abolished respectively by the p50 shRNA and PFT-α. Both p50 shRNA and PFT-α attenuated Aβ25-35-induced expression as well as nuclear translocation of all three transcription factors, namely p65, p50, and p53. Interestingly, p50 binding to the promoters of its target genes required p53 activity, whereas p50 also negatively regulated p53 binding to its target sequences. Suppression of sestrin2 expression by siRNA enhanced Aβ25-35- and Aβ1-42-induced production of reactive oxygen species (ROS), lipid peroxidation, and formation of 8-hydroxy-2-deoxyguanosine (8-OH-dG). In contrast, overexpression of the sestrin2 N-terminal or C-terminal fragments neutralized Aβ25-35-induced ROS production. We concluded that Aβ-induced sestrin2 contributing to antioxidant effects in neurons is in part mediated by p53 and NF-κB, which also mutually affect the expression of each other.
淀粉样β肽（Aβ）组成的老年斑的积累是阿尔茨海默病（AD）的病理学标志。各种应激源诱导的Sesrin2 已知可促进自噬并发挥抗氧化作用。在这项工作中，我们揭示了 Aβ诱导 Sesrin2 的分子机制，并测试了抗氧化作用除了调节自噬外，是否也有助于其在原代大鼠皮质神经元中的神经保护作用。我们发现 Aβ25-35 触发了核因子-κB（NF-κB）的两个亚基 p65 和 p50 以及 p53 的核易位。p65 siRNA、NF-κB 抑制剂 SN50 和 p53 抑制剂 pifithrin-α（PFT-α）可消除 Aβ25-35 诱导的 Sesrin2 表达。此外，Aβ25-35 增强了 p50 和 p53 与 Sesrin2 基因启动子的结合，p50 shRNA 和 PFT-α 分别消除了这种结合。p50 shRNA 和 PFT-α 均减弱了 Aβ25-35 诱导的三种转录因子（即 p65、p50 和 p53）的表达及核易位。有趣的是，p50 与靶基因启动子的结合需要 p53 活性，而 p50 也负调控 p53 与靶序列的结合。siRNA 抑制 Sesrin2 表达增强了 Aβ25-35 和 Aβ1-42 诱导的活性氧（ROS）产生、脂质过氧化和 8-羟基-2-脱氧鸟苷（8-OH-dG）的形成。相反，Sesrin2 N 端或 C 端片段的过表达中和了 Aβ25-35 诱导的 ROS 产生。我们得出结论，Aβ 诱导的神经元中Sesrin2 的抗氧化作用部分是由 p53 和 NF-κB 介导的，它们也相互影响彼此的表达。
