Autophagy impairment mediated by S-nitrosation of ATG4B leads to neurotoxicity in response to hyperglycemia
Autophagy impairment mediated by S-nitrosation of ATG4B leads to neurotoxicity in response to hyperglycemia
复制标题
ATG4B S-亚硝化介导的自噬损伤会导致高血糖反应的神经毒性。
DOI：
10.1080/15548627.2017.1320467
复制
发表时间：
2017-01-01
期刊：
影响因子：
13.3
通讯作者：
Chen, Chang
中科院分区：
文献类型：
--
作者：
Li, Yazi;Zhang, Yuying;Chen, Chang
大多数糖尿病患者会出现神经病变，中枢神经系统(CNS)神经变性的患病率也在增加。然而，人们对这背后的机制知之甚少。在这里，我们首先观察到，在高血糖的糖尿病GK大鼠的海马区，巨自噬/自噬受到抑制，而在没有高血糖的ob/ob小鼠中，这一点没有变化。高糖可直接抑制小鼠原代海马神经元的自噬。此外，自噬在高糖诱导的神经毒性中具有保护作用。进一步的研究表明，高糖抑制了自噬通量，这是由于MRFP-GFP-LC3斑点分析表明自噬小体合成受损所致。我们发现，自噬的减少依赖于在高糖条件下产生的NO。因此，基于LC-MS/MS对S亚硝化蛋白进行了定量蛋白质组学分析，在GK大鼠的海马区发现了一个核心自噬蛋白，即S亚硝化的ATG4B。在高糖培养的神经细胞中，ATG4B也被证实为S亚硝化。ATG4B在加工未修饰的前体ATG8家族蛋白和从脂化的ATG8家族蛋白中去结合PE的活性都被Cys189和Cys292位的S亚硝化所影响，而这些都是有效的自噬小体生物发生所必需的。此外，与其他底物相比，S亚硝化对GABARAPL1前驱体的ATG4B工艺影响最小。最后，ATG4B S亚硝化被证实是导致高糖反应中自噬和神经毒性减少的原因。综上所述，由S介导的ATG4B亚硝化导致的自噬损伤导致了对高血糖反应的神经毒性。我们的研究揭示了高血糖与中枢神经系统毒性之间的新机制，并表明S亚硝化是核心自噬机制的一种新的转录后修饰。
The majority of diabetic patients develop neuropathy and there is an increasing prevalence of neurodegeneration in the central nervous system (CNS). However, the mechanism behind this is poorly understood. Here we first observed that macroautophagy/autophagy was suppressed in the hippocampus of diabetic GK rats with hyperglycemia, whereas it was unchanged in ob/ob mice without hyperglycemia. Autophagy could be directly inhibited by high glucose in mouse primary hippocampal neurons. Moreover, autophagy was protective in high-glucose-induced neurotoxicity. Further studies revealed that autophagic flux was suppressed by high glucose due to impaired autophagosome synthesis illustrated by mRFP-GFP-LC3 puncta analysis. We showed that decreased autophagy was dependent on NO produced under high glucose conditions. Therefore, (LC-MS/MS)-based quantitative proteomic analysis of protein S-nitrosation was performed and a core autophagy protein, ATG4B was found to be S-nitrosated in the hippocampus of GK rats. ATG4B was also verified to be S-nitrosated in neuronal cells cultured with high glucose. The activities of ATG4B in the processing of unmodified, precursor Atg8-family proteins and in the deconjugation of PE from lipidated Atg8-family proteins, which are essential for efficient autophagosome biogenesis were both compromised by S-nitrosation at Cys189 and Cys292 sites. In addition, ATG4B processing of the GABARAPL1 precursor was affected the least by S-nitrosation compared with other substrates. Finally, ATG4B S-nitrosation was verified to be responsible for decreased autophagy and neurotoxicity in response to high glucose. In conclusion, autophagy impairment mediated by S-nitrosation of ATG4B leads to neurotoxicity in response to hyperglycemia. Our research reveals a novel mechanism linking hyperglycemia with CNS neurotoxicity and shows that S-nitrosation is a novel post-transcriptional modification of the core autophagy machinery.