Wang Li, Xu Xiao-Bin, You Wen-Wen, Lin Xiao-Xia, Li Cheng-Tan, Qian Hao-Ran, Zhang Li-Hui, Yang Yi
Department of Pharmacology, Hangzhou Key Laboratory of Medical Neurobiology, School of Medicine, Hangzhou Normal University, Hangzhou 310036, China.
Sir Run Run Shaw Hospital, Medical College of Zhejiang University, Hangzhou 310016, China.
Neurosci Lett. 2017 Nov 20;661:63-70. doi: 10.1016/j.neulet.2017.09.055. Epub 2017 Sep 28.
The abnormal expression of the autophagy-related protein Beclin 1 has been implicated in Alzheimer's disease (AD) brains, whereas the precise involvement of Caspase-mediated Beclin 1 cleavage in AD neurons has not yet been fully clarified. In this study, we investigated the distribution of Beclin 1 fragments in neurons with AD-like injury. Our results demonstrated that Beclin 1 was expressed in neurons but not in astrocytes in both neuron-glia co-cultures and in cortical tissue slices. The full length and C-terminal fragments of human Beclin 1 was mainly expressed in cytoplasm, while the N-terminal fragment of Beclin 1 was predominantly localized in nucleus. Compared to amyloid-β (Aβ) treatment control, exposure of PC12 cells or cortical neurons to Aβ resulted in cell injury, with the appearance of neuritic shortening, reduced nuclear diameter in PC12 cells, beading formation and fragmentation in cortical neurons. A partial nuclear translocation of Beclin 1 was detected in cells incubated with Aβ, which could be inhibited by the administration of pan-Caspase inhibitor or Caspase 3 specific inhibitor. Moreover, Beclin 1 mutation at 146/149 sites was resistant to Aβ-induced nuclear translocation. The nuclear translocation of Beclin 1 could also been detected in the brains of 12-month-old APP/PS1 transgenic mice. Our findings suggest that after Caspase 3-mediated Beclin 1 cleavage at 146/149 sites, the N-terminal fragments of Beclin 1 may partially translocate into nuclei in neurons subjected to AD-like injury.
自噬相关蛋白Beclin 1的异常表达与阿尔茨海默病（AD）脑有关，而半胱天冬酶介导的Beclin 1裂解在AD神经元中的具体作用尚未完全阐明。在本研究中，我们调查了Beclin 1片段在具有AD样损伤的神经元中的分布。我们的结果表明，在神经元-胶质细胞共培养物和皮质组织切片中，Beclin 1在神经元中表达，但在星形胶质细胞中不表达。人Beclin 1的全长和C末端片段主要在细胞质中表达，而Beclin 1的N末端片段主要定位于细胞核。与淀粉样β蛋白（Aβ）处理对照相比，PC12细胞或皮质神经元暴露于Aβ会导致细胞损伤，出现神经突缩短、PC12细胞核直径减小、皮质神经元中形成串珠和碎片化。在用Aβ孵育的细胞中检测到Beclin 1的部分核转位，这可被泛半胱天冬酶抑制剂或半胱天冬酶3特异性抑制剂抑制。此外，146/149位点的Beclin 1突变对Aβ诱导的核转位具有抗性。在12月龄APP/PS1转基因小鼠的脑中也检测到Beclin 1的核转位。我们的研究结果表明，在半胱天冬酶3介导的Beclin 1在146/149位点裂解后，Beclin 1的N末端片段可能会部分转位到遭受AD样损伤的神经元的细胞核中。
