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阿尔茨海默病中O-GlcNAc糖基化减少是脑葡萄糖代谢降低与tau蛋白病理之间的连接步骤 |
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Reduced O-GlcNAcylation links lower brain glucose metabolism and tau pathology in Alzheimer's disease |
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Liu, F., Shi, J., Tanimukai, H., Gu, J., Gu, J., Grundke-Iqbal, I., Iqbal, K., Gong, C.-X 2009/7/29 14:23:00 |
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Brain, 2009, Volume 132, Issue 7
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It has been established for a long time that brain glucose metabolism is impaired in Alzheimer's disease. Recent studies have demonstrated that impaired brain glucose metabolism precedes the appearance of clinical symptoms, implying its active role in the development of Alzheimer's disease. However, the molecular mechanism by which this impairment contributes to the disease is not known. In this study, we demonstrated that protein O-GlcNAcylation, a common post-translational modification of nucleocytoplasmic proteins with β-N-acetyl-glucosamine and a process regulated by glucose metabolism, was markedly decreased in Alzheimer's disease cerebrum. More importantly, the decrease in O-GlcNAc correlated negatively with phosphorylation at most phosphorylation sites of tau protein, which is known to play a crucial role in the neurofibrillary degeneration of Alzheimer's disease. We also found that hyperphosphorylated tau contained 4-fold less O-GlcNAc than non- hyperphosphorylated tau, demonstrating for the first time an inverse relationship between O-GlcNAcylation and phosphorylation of tau in the human brain. Downregulation of O-GlcNAcylation by knockdown of O-GlcNAc transferase with small hairpin RNA led to increased phosphorylation of tau in HEK-293 cells. Inhibition of the hexosamine biosynthesis pathway in rat brain resulted in decreased O-GlcNAcylation and increased phosphorylation of tau, which resembled changes of O-GlcNAcylation and phosphorylation of tau in rodent brains with decreased glucose metabolism induced by fasting, but not those in rat brains when protein phosphatase 2A was inhibited. Comparison of tau phosphorylation patterns under various conditions suggests that abnormal tau hyperphosphorylation in Alzheimer's disease brain may result from downregulation of both O-GlcNAcylation and protein phosphatase 2A. These findings suggest that impaired brain glucose metabolism leads to abnormal hyperphosphorylation of tau and neurofibrillary degeneration via downregulation of tau O-GlcNAcylation in Alzheimer's disease. Thus, restoration of brain tau O-GlcNAcylation and protein phosphatase 2A activity may offer promising therapeutic targets for treating Alzheimer's disease.
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Correspondence Address: Gong, C.-X.; Department of Neurochemistry, New York State Institute for Basic Research, 1050 Forest Hill Road, Staten Island, NY 10314, United States; email:cxgong@mail.csi.cuny.edu |
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疾病资源中心
王燕燕 王曙
上海交通大学附属瑞金医院内分泌科
患者,女,69岁。2009年1月无明显诱因下出现乏力,当时程度较轻,未予以重视。2009年3月患者乏力症状加重,尿色逐渐加深,大便习惯改变,颜色变淡。4月18日入我院感染科治疗,诉轻度头晕、心慌,体重减轻10kg。无肝区疼痛,无发热,无腹痛、腹泻、腹胀、里急后重,无恶性、呕吐等。入院半月前于外院就诊,查肝功能:ALT 601IU/L,AST 785IU/L,TBIL 97.7umol/L,白蛋白 41g/L,甲状腺功能:游离T3 30.6pmol/L,游离T4 51.9pmol/L,心电图示快速房颤。
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