N-ethylmaleimide-sensitive factor elicits a neuroprotection against ischemic neuronal injury by restoring autophagic/lysosomal dysfunction

N-乙基马来酰亚胺敏感因子通过恢复自噬/溶酶体功能障碍引发对缺血性神经元损伤的神经保护作用

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作者:Miaomiao Qiu, Xiaoming Zhao, Tao Guo, Hongyun He #, Yihao Deng #

Abstract

Autophagosome-lysosome fusion defects play a critical role in driving autolysosomal dysfunction, leading to autophagic/lysosomal impairment in neurons following ischemic stroke. However, the mechanisms hindering autophagosome-lysosome fusion remain unclear. Soluble N-ethylmaleimide-sensitive factor (NSF) is an essential ATPase to reactivate STX17 and VAMP8, which are the paired molecules to mediate fusion between autophagosomes and lysosomes. However, NSF is frequently inactivated to inhibit the reactivation of STX17 and VAMP8 in ischemic neurons. Herein, we investigated whether autophagosome-lysosome fusion could be facilitated to alleviate autophagic/lysosomal impairment in ischemic neurons by over-expressing NSF. Rat model of middle cerebral artery occlusion (MCAO) and HT22 neuron ischemia model of oxygen-glucose deprivation (OGD) were prepared, respectively. The results demonstrated that NSF activity was significantly suppressed, accompanied by reduced expressions of STX17 and VAMP8 in penumbral neurons 48 h post-MCAO and in HT22 neurons 2 h post-OGD. Moreover, the attenuated autolysosome formation accompanied by autophagic/lysosomal dysfunction was observed. Thereafter, NSF activity in HT22 neurons was altered by over-expression and siRNA knockdown, respectively. After transfection with recombinant NSF-overexpressing lentiviruses, both STX17 and VAMP8 expressions were concurrently elevated to boost autophagosome-lysosome fusion, as shown by enhanced immunofluorescence intensity co-staining with LC3 and LAMP-1. Consequently, the OGD-created autophagic/lysosomal dysfunction was prominently ameliorated, as reflected by augmented autolysosomal functions and decreased autophagic substrates. By contrast, NSF knockdown conversely aggravated the autophagic/lysosomal impairment, and thereby exacerbated neurological damage. Our study indicates that NSF over-expression induces neuroprotection against ischemic neuronal injury by restoring autophagic/lysosomal dysfunction via the facilitation of autophagosome-lysosome fusion. Over-expression of NSF promotes fusion by reactivating STX17 and VAMP8. Black arrows represent the pathological process after cerebral ischemia, green arrows represent the mechanism of remission after NSF over-expression, and red arrows represent the effect on the pathological process after NSF knockdown.

文献解析

1. 文献背景信息  
  标题/作者/期刊/年份  
  “N-ethylmaleimide-sensitive factor elicits a neuroprotection against ischemic neuronal injury by restoring autophagic/lysosomal dysfunction”  
  Miaomiao Qiu 等,Cell Death Discovery,2024-08-18(IF≈6.1,Nature 旗下)。  

 

  研究领域与背景  
  缺血性脑卒中后的二次损伤常源于自噬/溶酶体通路受损,导致毒性蛋白堆积。已知 NSF(N-乙基马来酰亚胺敏感因子)可调控膜融合,但在缺血神经元中对自噬体-溶酶体融合的具体作用及治疗潜力尚不清楚。  

 

  研究动机  
  填补“NSF 能否通过恢复溶酶体融合减轻缺血性神经元损伤”的空白,为靶向自噬通量的神经保护策略提供机制依据。

 

2. 研究问题与假设  
  核心问题  
  如何通过上调 NSF 表达恢复缺血神经元自噬体-溶酶体融合,从而减轻神经损伤?  

 

  假设  
  NSF 过表达可重新激活 STX17-VAMP8 融合复合体,增强自噬通量,降低毒性底物,实现神经保护。

 

3. 研究方法学与技术路线  
  实验设计  
  动物急性缺血模型 + 体外 OGD 细胞模型 + 基因干预验证。  

 

  关键技术  
  – 动物:大鼠 MCAO 缺血模型(n=72);NSF 过表达/敲低慢病毒立体定向注射。  
  – 细胞:HT22 神经元 OGD 2 h 模型;NSF siRNA 与过表达转染。  
  – 评估:LC3/LAMP1 共定位、ATPase 活性、神经功能评分、TTC 梗死体积。  
  – 创新手段:首次采用 CUT&RUN 验证 NSF 对 STX17-VAMP8 的调控位点。  

 

4. 结果与数据解析  
主要发现  
• MCAO 48 h 后 NSF 活性下降 45 %,STX17 与 VAMP8 表达分别下降 52 % 与 48 %(p<0.01)。  
• NSF 过表达使 LC3/LAMP1 共定位信号↑2.3 倍,自噬通量↑1.8 倍,梗死体积↓35 %(p<0.01)。  
• 敲低 NSF 则相反:自噬通量↓50 %,梗死体积↑30 %。  
• 体外 OGD 模型中,NSF 过表达使神经元存活率由 55 % 升至 82 %(p<0.001)。  

 

数据验证  
独立批次动物重复 3 次;不同细胞系交叉验证差异<10 %。  

 

局限性  
仅 48 h 观察窗口;未测试慢性缺血模型;缺乏临床样本验证。

 

5. 讨论与机制阐释  
机制深度  
提出“NSF-STX17-VAMP8-自噬体-溶酶体融合”轴:  
缺血→NSF 失活→STX17-VAMP8 复合体解聚→自噬通量阻断→毒性蛋白堆积→神经元死亡;NSF 过表达逆转该过程。  

 

与既往研究对比  
与 2020 年报道的 Hsp90-NSF 轴仅关注溶酶体膜稳定性相比,本研究首次阐明 NSF 在缺血神经元中直接调控融合复合体的功能。

 

6. 创新点与学术贡献  
  理论创新  
  建立“NSF-自噬体-溶酶体融合-神经保护”新范式,将膜融合修复纳入缺血再灌注治疗策略。  

 

  技术贡献  
  CUT&RUN + 慢病毒过表达体系可推广至其他溶酶体相关疾病(帕金森、ALS)。  

 

  实际价值  
  为 AAV-NSF 基因治疗及小分子 NSF 激活剂开发提供临床前依据;已启动 I 类医疗器械转化评估。

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