An impaired mitochondrial electron transport chain increases retention of the hypoxia imaging agent diacetylbis(4-methylthiosemicarbazonato)copperII
An impaired mitochondrial electron transport chain increases retention of the hypoxia imaging agent diacetylbis(4-methylthiosemicarbazonato)copperII
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DOI：
10.1073/pnas.1116227108
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发表时间：
2012-01-03
影响因子：
11.1
通讯作者：
Crouch, Peter J.
中科院分区：
文献类型：
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作者：
Donnelly, Paul S.;Liddell, Jeffrey R.;Crouch, Peter J.
放射性标记的二乙酰基双（4-甲基氨基硫脲）铜（II）[Cu-II（atsm）]是一种有效的正电子发射断层扫描成像剂，用于心肌缺血，缺氧性肿瘤和具有局部氧化应激的脑疾病，如线粒体肌病，脑病和乳酸酸中毒伴卒中样发作（MELAS）和帕金森病。一个过度升高的还原状态是常见的这些条件，并已提出作为一个重要的机制，影响细胞保留铜从铜-II（atsm）。然而，尚未提供来自全细胞模型的数据来证明这种机制。本研究使用了一种独特的细胞培养模型，线粒体异种杂交体，提供全细胞的机械数据细胞保留铜从铜-II（atsm）。核和线粒体之间的遗传不相容性的线粒体电子传递链（ETC）在xenocybrid细胞的编码亚基妥协的ETC的正常功能。作为这种损害的ETC的结果，我们显示xenocybrid细胞上调糖酵解ATP的生产和积累NADH。与对照细胞相比，用Cu-II（atsm）处理后，异种杂交细胞保留更多的Cu。通过用金属响应元件报告构建体对细胞进行电泳，显示Cu保留的增加涉及Cu-II（atsm）诱导的细胞内生物可利用Cu的增加，特别是在异种杂交细胞内。使用在缺氧条件下生长的细胞进行的平行实验证实，受损的ETC和升高的NADH水平有助于从Cu-II（atsm）增加Cu的细胞保留。使用这些细胞培养模型，我们的数据表明，损害ETC功能，由于没有O-2作为终端电子受体或功能障碍的个别组件的ETC，是一个重要的决定因素，在驱动细胞内解离的铜-II（atsm），增加细胞保留的铜。
Radiolabeled diacetylbis(4-methylthiosemicarbazonato)copper(II) [Cu-II(atsm)] is an effective positron-emission tomography imaging agent for myocardial ischemia, hypoxic tumors, and brain disorders with regionalized oxidative stress, such as mitochondrial myopathy, encephalopathy, and lactic acidosis with stroke-like episodes (MELAS) and Parkinson's disease. An excessively elevated reductive state is common to these conditions and has been proposed as an important mechanism affecting cellular retention of Cu from Cu-II(atsm). However, data from whole-cell models to demonstrate this mechanism have not yet been provided. The present study used a unique cell culture model, mitochondrial xenocybrids, to provide whole-cell mechanistic data on cellular retention of Cu from Cu-II(atsm). Genetic incompatibility between nuclear and mitochondrial encoded subunits of the mitochondrial electron transport chain (ETC) in xenocybrid cells compromises normal function of the ETC. As a consequence of this impairment to the ETC we show xenocybrid cells upregulate glycolytic ATP production and accumulate NADH. Compared to control cells the xenocybrid cells retained more Cu after being treated with Cu-II(atsm). By transfecting the cells with a metal-responsive element reporter construct the increase in Cu retention was shown to involve a Cu-II(atsm) induced increase in intracellular bioavailable Cu specifically within the xenocybrid cells. Parallel experiments using cells grown under hypoxic conditions confirmed that a compromised ETC and elevated NADH levels contribute to increased cellular retention of Cu from Cu-II(atsm). Using these cell culture models our data demonstrate that compromised ETC function, due to the absence of O-2 as the terminal electron acceptor or dysfunction of individual components of the ETC, is an important determinant in driving the intracellular dissociation of Cu-II(atsm) that increases cellular retention of the Cu.