Singer Steven M, Zainelli Gina M, Norlund Maryam A, Lee John M, Muma Nancy A
The Department of Pharmacology, Loyola University Medical Center, 2160 S First Avenue, Maywood, IL 60153, USA.
Neurochem Int. 2002 Jan;40(1):17-30. doi: 10.1016/s0197-0186(01)00061-4.
Transglutaminase-catalyzed epsilon(gamma-glutamyl)lysine cross-links exist in Alzheimer's disease (AD) paired helical filament (PHF) tau protein but not normal soluble tau. To test the hypothesis that these cross-links could play a role in the formation of neurofibrillary tangles (NFT), we used single- and double-label immunofluorescence confocal microscopy and immunoaffinity purification and immunoblotting to examine epsilon(gamma-glutamyl)lysine cross-links in AD and control brains. The number of neurons that are immunoreactive with an antibody directed at the epsilon-(gamma-glutamyl)lysine bond was significantly higher in AD cortex compared with age-matched controls and schizophrenics. PHF tau-directed antibodies AT8, MC-1 and PHF-1 co-localized with epsilon(gamma-glutamyl)lysine immunolabeling in AD NFT. Immunoaffinity purification and immunoblotting experiments demonstrated that PHF tau contains epsilon(gamma-glutamyl)lysine bonds in parietal and frontal cortex in AD. In control cases with NFT present in the entorhinal cortex and hippocampus, indicative of Braak and Braak stage II, epsilon(gamma-glutamyl)lysine bonds were present in PHF tau in parietal and frontal cortex, despite the lack of microscopically detectable NFT or senile plaques in these cortical regions. The presence of PHF tau with epsilon(gamma-glutamyl)lysine bonds in brain regions devoid of NFT in stage II (but regions, which would be expected to contain NFT in stage III) suggests that these bonds occur early in the formation of NFT.
转谷氨酰胺酶催化的ε（γ-谷氨酰基）赖氨酸交联存在于阿尔茨海默病（AD）的配对螺旋丝（PHF）tau蛋白中，而正常可溶性tau蛋白中则不存在。为了验证这些交联可能在神经原纤维缠结（NFT）形成中起作用的假说，我们使用单标和双标免疫荧光共聚焦显微镜以及免疫亲和纯化和免疫印迹法，来检测AD和对照大脑中的ε（γ-谷氨酰基）赖氨酸交联。与年龄匹配的对照和精神分裂症患者相比，AD皮质中与针对ε-（γ-谷氨酰基）赖氨酸键的抗体发生免疫反应的神经元数量明显更多。针对PHF tau的抗体AT8、MC-1和PHF-1在AD NFT中与ε（γ-谷氨酰基）赖氨酸免疫标记共定位。免疫亲和纯化和免疫印迹实验表明，AD顶叶和额叶皮质中的PHF tau含有ε（γ-谷氨酰基）赖氨酸键。在内嗅皮质和海马体中存在NFT的对照病例中，这表明处于Braak和Braak II期，尽管在这些皮质区域缺乏显微镜下可检测到的NFT或老年斑，但顶叶和额叶皮质中的PHF tau中仍存在ε（γ-谷氨酰基）赖氨酸键。在II期无NFT的脑区（但预计在III期会含有NFT的区域）中存在带有ε（γ-谷氨酰基）赖氨酸键的PHF tau，这表明这些键在NFT形成的早期就已出现。
