Effect of p62 on tau hyperphosphorylation in a rat model of Alzheimer＇s disease

• Published in: 中国神经再生研究：英文版 2012, Vol.7 (17), p.1304-1311
• Main Author: Xianhong Zheng Weiwei Wang Ruizhi Liu Honglan Huang Rihui Zhang Liankun Sun
• Format: Article
• Language: English
• Subjects: tau蛋白; 大鼠模型; 微管相关蛋白; 抗氧化防御系统; 环氧氯丙烷; 蛋白磷酸化; 阿尔茨海默氏病; 阿尔茨海默氏症
• ISSN: 1673-5374

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 13-amyloid protein into the hippocampus and ~-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 Aizheimer＇s disease rats, and the autophagy related proteins Atg12-Atg5, microtubule-associated protein 1 light chain 3-phosphatidylethanolamine and Beclinl 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.