Mitochondria are a direct site of Aβ accumulation in Alzheimer's disease neurons:: implications for free radical generation and oxidative damage in disease progression
Mitochondria are a direct site of Aβ accumulation in Alzheimer's disease neurons:: implications for free radical generation and oxidative damage in disease progression
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DOI：
10.1093/hmg/ddl066
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发表时间：
2006-05-01
影响因子：
3.5
通讯作者：
Reddy, PH
中科院分区：
文献类型：
--
作者：
Manczak, M;Anekonda, TS;Reddy, PH
阿尔茨海默病（AD）是一种复杂的神经退行性疾病，其特征在于老年个体的认知功能受损。在最近的APP转基因小鼠的全球基因表达研究中，我们发现线粒体基因的表达升高，我们假设这是一种代偿反应，因为突变APP和/或淀粉样蛋白β（A β）的过度表达引起线粒体氧化损伤。我们在一系列实验中研究了这一假设，研究了APP和A β定位于线粒体的形式，以及这些物种的存在是否与线粒体功能障碍和氧化损伤有关。使用免疫印迹、毛地黄皂苷分级分离、免疫荧光和电子显微镜技术，我们发现了Tg 2576小鼠脑切片和表达突变型人APP的小鼠神经母细胞瘤细胞中突变型APP衍生物与线粒体之间的关系。此外，为了确定突变型APP/A β与氧化损伤之间的功能关系，我们定量了A β水平、过氧化氢产生、Tg 2576小鼠和年龄匹配的野生型（WT）同窝出生仔中的细胞色素氧化酶活性和羰基蛋白。与年龄匹配的WT同窝出生小鼠相比，发现Tg 2576小鼠中的过氧化氢水平显著增加，并且与Tg 2576小鼠中的可溶性A β水平直接相关，表明可溶性A β可能是Tg 2576小鼠AD进展中过氧化氢产生的原因。与年龄匹配的WT同窝小鼠相比，发现Tg 2576小鼠的细胞色素c氧化酶活性降低，表明突变型APP和可溶性A β损害AD发生和进展中的线粒体代谢。在A β斑块出现之前，在年轻的Tg 2576小鼠中发现过氧化氢增加和细胞色素氧化酶活性降低。这些发现表明，早期的脑血管靶向治疗干预可能有效地延缓老年人的AD进展和治疗AD患者。
Alzheimer's disease (AD) is a complex, neurodegenerative disease characterized by the impairment of cognitive function in elderly individuals. In a recent global gene expression study of APP transgenic mice, we found elevated expression of mitochondrial genes, which we hypothesize represents a compensatory response because of mitochondrial oxidative damage caused by the over-expression of mutant APP and/or amyloid beta (A beta). We investigated this hypothesis in a series of experiments examining what forms of APP and A beta localize to the mitochondria, and whether the presence of these species is associated with mitochondrial dysfunction and oxidative damage. Using immunoblotting, digitonin fractionation, immunofluorescence, and electron microscopy techniques, we found a relationship between mutant APP derivatives and mitochondria in brain slices from Tg2576 mice and in mouse neuroblastoma cells expressing mutant human APP. Further, to determine the functional relationship between mutant APP/A beta and oxidative damage, we quantified A beta levels, hydrogen peroxide production, cytochrome oxidase activity and carbonyl proteins in Tg2576 mice and age-matched wild-type (WT) littermates. Hydrogen peroxide levels were found to be significantly increased in Tg2576 mice when compared with age-matched WT littermates and directly correlated with levels of soluble A beta in Tg2576 mice, suggesting that soluble A beta may be responsible for the production of hydrogen peroxide in AD progression in Tg2576 mice. Cytochrome c oxidase activity was found to be decreased in Tg2576 mice when compared with age-matched WT littermates, suggesting that mutant APP and soluble A beta impair mitochondrial metabolism in AD development and progression. An increase in hydrogen peroxide and a decrease in cytochrome oxidase activity were found in young Tg2576 mice, prior to the appearance of A beta plaques. These findings suggest that early mitochondrially targeted therapeutic interventions may be effective in delaying AD progression in elderly individuals and in treating AD patients.