Differential expression of oxidative phosphorylation genes in patients with Alzheimer's disease - Implications for early mitochonrial dysfunction and oxidative damage
Differential expression of oxidative phosphorylation genes in patients with Alzheimer's disease - Implications for early mitochonrial dysfunction and oxidative damage
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DOI：
10.1385/nmm:5:2:147
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发表时间：
2004-01-01
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;Park, BS;Reddy, PH
在阿尔茨海默病（AD）的发病机制中，越来越多的证据表明线粒体功能障碍是由氧化磷酸化（OXPHOS）分子缺陷引起的。本研究的目的是确定早期AD和明确AD患者脑标本中负责OXPHOS的线粒体基因mRNA表达的作用。本文采用实时定量聚合酶链反应（PCR）技术，研究了早期AD患者（n = 6）、确诊AD患者（n = 6）和对照组（n = 6）中11个线粒体编码基因的mRNA表达。利用免疫荧光技术，我们确定了AD患者和对照组脑组织中线粒体基因nadh 15-kDa亚基（复合体I）、细胞色素氧化酶亚基I（复合体IV）和atp酶δ亚基（复合体V）的差异表达。我们的定量反转录(RT)-PCR分析显示，在早期和确诊AD脑标本中，OXPHOS复合物I的线粒体基因下调。此外，与研究的所有其他亚基相比，亚基I的mRNA折叠变化减少幅度更大，这表明亚基I对OXPHOS至关重要。与复合体I基因下调相反，复合体III和复合体IV在早期和明确AD患者的脑标本中均显示mRNA表达增加，表明对能量产生有很大的需求。此外，线粒体基因表达在AD患者中差异很大，表明线粒体DNA缺陷可能是导致AD患者表型异质性的原因。我们对细胞色素氧化酶和三磷酸腺苷酶δ亚基的免疫荧光分析表明，只有神经元亚群在阿尔茨海默病大脑中有差异表达。我们对8-羟基鸟苷和细胞色素氧化酶的双标记免疫荧光分析表明，只有选择性的、过表达的细胞色素氧化酶神经元在AD大脑中发生氧化损伤。基于这些结果，我们提出细胞色素氧化酶基因表达的增加可能是存活神经元功能补偿的结果，或者是与氧化损伤增加相关的早期线粒体改变的结果。
In Alzheimer's disease (AD) pathogenesis, increasing evidence implicates mitochondrial dysfunction resulting from molecular defects in oxidative phosphorylation (OXPHOS). The objective of the present study was to determine the role of mRNA expression of mitochondrial genes responsible for OXPHOS in brain specimens from early AD and definite AD patients. In the present article, using quantitative real-time polymerase chain reaction (PCR) techniques, we studied mRNA expression of 11 mitochondrial-encoded genes in early AD patients (n = 6), definite AD patients (n = 6), and control subjects (n = 6). Using imniunofluorescence techniques, we determined differentially expressed mitochondrial genes-NADH 15-kDa subunit (complex I), cytochrome oxidase subunit I (complex IV), and ATPase delta-subunit (complex V)-in the brain sections of AD patients and control subjects. Our quantitative reverse transcription (RT)-PCR analysis revealed a downregulation of mitochondrial genes in complex I of OXPHOS in both early and definite AD brain specimens. Further, the decrease of mRNA fold changes was higher for subunit I compared to all other subunits studied, suggesting that subunit I is critical for OXPHOS. Contrary to the downregulation of genes in complex I, complexes III and IV showed increased mRNA expressions in the brain specimens of both early and definite AD patients, suggesting a great demand on energy production. Further, mitochondrial gene expression varied greatly across AD patients, suggesting that mitochondrial DNA defects may be responsible for the heterogeneity of the phenotype in AD patients. Our immunofluorescence analyses of cytochrome oxidase and of the ATPase delta-subunit suggest that only subpopulations of neurons are differentially expressed in AD brains. Our double-labeling immunofluorescence analyses of 8-hydroxyguanosine and of cytochrome oxidase suggest that only selective, over-expressed neurons with cytochrome oxidase undergo oxidative damage in AD brains. Based on these results, we propose that an increase in cytochrome oxidase gene expression might be the result of functional compensation by the surviving neurons or an early mitochondrial alteration related to increased oxidative damage.