Zheng Xianhong, Wang Weiwei, Liu Ruizhi, Huang Honglan, Zhang Rihui, Sun Liankun
Department of Cytobiology, Norman Bethune College of Medicine, Jilin University, Changchun 130021, Jilin Province, China.
Department of Pathophysiology, Norman Bethune College of Medicine, Jilin University, Changchun 130021, Jilin Province, China.
Neural Regen Res. 2012 Jun 15;7(17):1304-11. doi: 10.3969/j.issn.1673-5374.2012.17.004.
Tau hyperphosphorylation is a main cause of neuronal loss in Alzheimer's disease, which can be caused by many factors, including oxidative stress. The multifunctional protein p62, which exists in neurofibrillary tangles and causes aggregation of hyperphosphorylated tau, not only serves as a receptor in selective autophagy, but also regulates oxidative stress. However, whether p62 participates in oxidative stress-induced tau hyperphosphorylation remains unclear. In this study, we produced an Alzheimer's disease rat model by injecting β-amyloid protein into the hippocampus and β-galactose intraperitoneally. Hematoxylin-eosin staining was used for morphological analysis of brain tissue, and western blotting, immunohistochemistry and reverse transcription-PCR were employed to study p62 and autophagy related proteins, antioxidant defense system kelch-like ECH-associated protein 1-NF-E2-related factor 2 related proteins and hyperphosphorylated tau, respectively. The number of neurons in the brain decreased in Alzheimer's disease rats, and the autophagy related proteins Atg12-Atg5, microtubule-associated protein 1 light chain 3-phosphatidylethanolamine and Beclin1 increased significantly, while p62 expression reduced. Expression of kelch-like ECH-associated protein 1 increased, NF-E2-related factor 2 protein and the downstream gene products of glutamate cysteine ligase catalytic subunit and glutamate cysteine ligase modulatory subunit decreased, and hyperphosphorylated tau increased. These findings demonstrate that autophagy levels increased and p62 levels decreased in the brains of Alzheimer's disease rats. Moreover, the anti-oxidative capability of the NF-E2-related factor 2-antioxidant response element pathway was decreased, which may be the cause of tau hyperphosphorylation in Alzheimer's disease brain tissue and the subsequent structural and functional damage to neurons.
tau蛋白过度磷酸化是阿尔茨海默病中神经元丢失的主要原因，其可由包括氧化应激在内的多种因素引起。多功能蛋白p62存在于神经原纤维缠结中并导致过度磷酸化tau蛋白聚集，它不仅作为选择性自噬中的一种受体，还调节氧化应激。然而，p62是否参与氧化应激诱导的tau蛋白过度磷酸化仍不清楚。在本研究中，我们通过向海马体注射β-淀粉样蛋白并腹腔注射β-半乳糖来制备阿尔茨海默病大鼠模型。苏木精-伊红染色用于脑组织的形态学分析，蛋白质免疫印迹法、免疫组织化学和逆转录聚合酶链反应分别用于研究p62和自噬相关蛋白、抗氧化防御系统kelch样ECH相关蛋白1-NF-E2相关因子2相关蛋白以及过度磷酸化的tau蛋白。阿尔茨海默病大鼠脑内神经元数量减少，自噬相关蛋白Atg12-Atg5、微管相关蛋白1轻链3-磷脂酰乙醇胺和Beclin1显著增加，而p62表达降低。kelch样ECH相关蛋白1表达增加，NF-E2相关因子2蛋白以及谷氨酸半胱氨酸连接酶催化亚基和谷氨酸半胱氨酸连接酶调节亚基的下游基因产物减少，过度磷酸化的tau蛋白增加。这些发现表明，阿尔茨海默病大鼠脑内自噬水平升高而p62水平降低。此外，NF-E2相关因子2-抗氧化反应元件通路的抗氧化能力下降，这可能是阿尔茨海默病脑组织中tau蛋白过度磷酸化以及随后神经元结构和功能损伤的原因。
