INTERACTION OF CHROMIUM WITH MITOCHONDRIA

本研究项目的总体目标是了解 铬(VI)化合物作为致癌物的机制。三位一体 我们计划用来解决这个问题的方法是：(1)线粒体 将被用作研究吸收-还原机制的模型系统 建议用于铬(VI)致癌，因为该细胞器含有 铬(VI)还原酶活性以及确定的DNA(Mt DNA) 序列；(2)铬与重复DNA序列的结合 将确定核来源，因为作为目标的核DNA可能不同 来自线粒体DNA的铬化合物；以及(3)致癌 铬(VI)化合物将与非致癌铬(III)进行比较 铬与线粒体DNA和重复DNA结合的化合物 为了区分与生物活性有关的相互作用， 铬化合物。 我们计划测试铬(VI)的还原活化假设 在特定的DNA序列上产生特定的铬-DNA加合物 优先受到攻击是因为它们的DNA结构。具体目标 建议的研究包括：(1)比较六价铬和三价铬。 它们与大鼠线粒体DNA形成铬络合物的能力 体内和体内重复的DNA。浅谈汽车车辙的形成与修复 Mt DNA和重复DNA片段中的铬-DNA加合物将被 用~(51)Cr标记的重铬酸钠处理后测定 氯化铬(III)。(2)确定铬的序列特异性 与线粒体和重复DNA的相互作用。该序列 线粒体DNA与铬-DNA加合物的特异性和碱性不稳定性 重复的DNA片段将使用DNA测序来确定 技巧。(3)确定铬(VI)的还原机理 线粒体NADH-泛醌氧化还原酶。铬的代谢(VI) 通过复数i和孤立分量将被确定。新一代人 还原时的活性铬(V)和自由基物种 这些体系中的铬(VI)将通过EPR光谱进行监测。(4) 测定顺铂(II)与大鼠线粒体结合的能力 重复DNA在体内和体外；以及(5)测定 铬对线粒体DNA复制和线粒体基因表达的影响。

The overall objective of this research project is to understand the mechanism by which chromium(VI) compounds act as carcinogens. The three approaches we plan to use in attacking this problem are: (1) mitochondria will be used as a model system for studying the uptake-reduction mechanism proposed for chromium(VI) carcinogenicity since this organelle contains chromium(VI) reductase activity as well as DNA (mt DNA) of defined sequence; (2) the binding of chromium to repetitive DNA sequences of nuclear origin will be determined since nuclear DNA may differ as a target for chromium compounds from mitochondrial DNA; and (3) carcinogenic chromium(VI) compounds will be compared with noncarcinogenic chromium(III) compounds with respect to chromium binding to mt DNA and repetitive DNA in order to distinguish interactions related to the biological activity of the chromium compounds. We plan to test the hypothesis that reductive activation of chromium(VI) results in specific chromium-DNA adducts at defined DNA sequences which are preferentially attacked because of their DNA structure. The specific aims of the proposed research are: (1) Compare chromium(VI) and chromium(III) for their ability to form chromium complexes with rat mitochondrial DNA and repetitive DNA in vivo and in tro. The formation and repair of chromium-DNA adducts in mt DNA and repetitive DNA fragments will be determined after treatment with 51Cr-labeled sodium dichromate and chromium(III) chloride. (2) Determine the sequence specificity of chromium interactions with mitochondrial and repetitive DNA. The sequence specificity and alkaline lability of the chromium-DNA adducts on mt DNA and repetitive DNA fragments will be determined using DNA sequencing techniques. (3) Determine the mechanism of chromium(VI) reduction by mitochondrial NADH-ubiquinone oxidoreductase. Metabolism of chromium(VI) by Complex I and isolated components will be determined. The generation of reactive chromium(V) and free radical species upon reduction of chromium(VI) by these systems will be monitored by EPR spectroscopy. (4) Determine the ability of cis-platinum(II) to bind to rat mitochondrial and repetitive DNA in vivo and in vitro; and (5) Determine the effect of chromium on the replication of mt DNA and on the expression of mt genes.