Novel Mechanisms of Quinone Toxicity

描述(由申请人提供)：苯醌和萘醌都被发现在各种细胞系统中扰乱蛋白质的处理和降解。蛋白质的处理和降解不仅限于蛋白酶体，还涉及蛋白质伴侣、未折叠蛋白反应(UPR)/内质网(ER)应激反应、侵袭体的形成和溶酶体自噬。喹酮类化合物已被发现影响这些系统中的每一个，并且改变的蛋白质处理正在成为醌诱导毒性的一个潜在的关键机制。我们的研究将集中在模型1，4-苯并苯并对苯二酚以及多巴胺衍生的1，2-对苯二酚和氨基色素，它们都被证明可以诱导蛋白质处理的变化。在目标1中，我们将表征所有主要蛋白质处理系统中由模型苯并和萘醌以及氨基色素引起的变化。这些实验将表征由于用反应性醌处理细胞而导致的蛋白质处理机制的变化，以及这种变化与细胞系统毒性的相关性。在目标2中，我们将定义芳基化和苯醌诱导的氧化应激在使用仅能进行氧化还原循环或既能氧化还原循环又能进行芳基化的受抑蛋白质处理中的各自作用。我们还将检测在稳定转染单电子还原酶、细胞色素P450还原酶或细胞色素b5还原酶的细胞中，苯醌引起的蛋白质处理的变化，这会导致苯醌电子氧化还原循环的增加和活性氧的产生。哺乳动物主要的苯醌还原酶NQO1和NQO2是高度多态的，变异等位基因的发生率很高，导致了显着的表型变化。因此，这些酶活性的缺乏或变化可能是苯醌毒性的易感因素。在目标3中，我们将研究NQO1和NQO2在调节苯二酚诱导的蛋白质处理变化和毒性中的作用。这些实验将在等基因的胰腺、乳腺和神经系统细胞系统中进行，旨在探索NQO1和NQO2在同一遗传背景中的作用。这些实验将在蛋白质处理水平上表征醌诱导的毒性的新机制，定义蛋白质处理变化在毒性中的相互关系和各自的作用，并确定NQO1和NQO2作为这些变化的易感因素的作用。这些研究将具有广泛的机制适用性，适用于各种器官系统。 公共卫生相关性：本应用的重点是在蛋白质处理水平上阐明外源和内源性苯二酚的新毒性机制。芳基化和氧化应激在苯醌诱导的蛋白质处理和毒性改变中的作用将被确定。苯醌还原酶的药物遗传学已被描述，它们具有高度的多态，可能是苯醌毒性的易感因素。这些研究将广泛适用于各种器官系统。

DESCRIPTION (provided by applicant): Both benzoquinones and naphthoquinones have been found to perturb protein handling and degradation in a variety of cellular systems. Protein handling and degradation is not restricted to the proteasome and also involves protein chaperones, the unfolded protein response (UPR)/endoplasmic reticulum (ER) stress response, formation of aggresomes and lysosomal autophagy. Quinones have been found to affect each of these systems and altered protein handling is emerging as a potentially key mechanism of quinone induced toxicity. Our studies will focus on model 1,4-benzo- and naphtho-quinones as well as the dopamine derived 1,2-quinone, aminochrome which have all been shown to induce changes in protein handling. In aim 1, we will characterize changes in all major protein handling systems induced by model benzo- and naphtho- quinones and by aminochrome. These experiments will characterize altered mechanisms of protein handling as a result of treatment of cells with reactive quinones and the relevance of such changes for toxicity in cellular systems. In aim 2, we will define the respective roles of arylation and quinone-induced oxidative stress in inhibited protein handling using quinones capable only of either redox cycling or of both redox cycling and arylation . We will also examine quinone induced changes in protein handling in cells stably transfected with the one electron reductases cytochrome P450 reductase or cytochrome b5 reductase which cause increased quinone one electron redox cycling and increased reactive oxygen generation. The major mammalian quinone reductases NQO1 and NQO2 are highly polymorphic with a high prevalence of variant alleles resulting in marked phenotypic changes. A lack or variation in activity of these enzymes may therefore represent susceptibility factors for quinone induced toxicity. In aim 3, we will examine the role of NQO1 and NQO2 in modulating quinone induced protein handling changes and toxicity. These experiments will be performed in isogenic pancreatic, breast and neural cellular systems specifically designed to explore the roles of NQO1 and NQO2 in the same genetic background Overall, these experiments will characterize novel mechanisms of quinone-induced toxicity at the level of protein handling, define the inter-relationships and the respective roles of protein handling changes in toxicity and define the role of NQO1 and NQO2 as susceptibility factors for these changes. The studies will have broad mechanistic applicability to a variety of organ systems. PUBLIC HEALTH RELEVANCE: The focus of this application is to elucidate novel mechanisms of toxicity of xenobiotic and endogenous quinones at the level of protein handling. The role of both arylation and oxidative stress in quinone-induced alterations in protein handling and toxicity will be defined. The pharmacogenetics of quinone reductases has been characterized and they are highly polymorphic and may represent susceptibility factors for quinone induced toxicity. The studies will have broad applicability to a variety of organ systems.