Structure/Function Studies of Quinone Reductase 2

描述(申请人提供)：拟议工作的目的是使用酶、结构、生化和生物学方法相结合的方法来研究苯醌还原酶2(QR2)的结构/功能关系。QR2的生物学功能仍然是未知的，尽管它的同源基因--苯醌还原酶1(QR1)已经得到了很好的描述。我们最近的研究表明，苯醌还原酶2(QR2)是许多天然多酚的潜在靶标，包括白藜芦醇类似物、黄酮类、查尔酮类化合物和一些香豆素衍生物。QR2还能还原CB1954的硝基和邻苯二酚类化合物，如肾上腺素。RNAi方法下调QR2进一步证明白藜芦醇处理的细胞和QR2下调细胞表现出相似的特性：对苯二酚毒性的抗性，抗氧化酶的表达增加，增殖速度降低。在这些研究的基础上，我们假设QR2具有与QR1非常不同的功能，因为它在底物特异性、相互作用的蛋白质伙伴和抑制剂方面具有与QR1不同的独特性质。我们进一步假设，QR2可能直接或间接地在过氧化氢酶和谷胱甘肽还原酶等抗氧化酶的表达中起关键的调节作用。因此，我们建议通过底物特异性研究来研究QR2的催化性质，特别是对神经毒性醌和药物代谢物的催化活性；抑制剂特异性研究；阐明QR2与其底物和抑制剂复合体中的结构；通过蛋白质组学方法鉴定相互作用的蛋白质和体内潜在的电子供体；以及QR2基因敲除细胞系的蛋白质表达谱。由于QR2基因多态性与特发性帕金森氏病、精神分裂症、酒精戒断症状和氯氮平诱导的粒细胞增多症有关，因此这一综合方法将有助于了解QR2基因的独特催化特性和生物学功能，以及了解QR2基因多态性与某些神经系统疾病的关系。

DESCRIPTION (provided by applicant): The aim of the proposed work is to use a combination of enzymatic, structural, biochemical, and biological approaches to study the structural/function relationship of quinone reductase 2 (QR2). The biological functions of QR2 are still virtually unknown, even though its close homolog, quinone reductase 1 (QR1), is well characterized. Our recent studies indicate that quinone reductase 2 (QR2) is the potential target of many natural polyphenols, including resveratrol analogs, flavonoids, chalconoids and some coumarin derivatives. QR2 is also active in the reduction of nitro groups of CB1954 and catechol quinones such as adrenochrome. QR2 knock down by RNAi method further demonstrated that resveratrol treated cells and QR2 knockdown cells exhibit similar properties: resistance to quinone toxicity, increased expression of anti-oxidant enzymes, and reduced proliferation rate. Based on those studies, we hypothesize that QR2 possesses very different functions from QR1 by virtual of its unique properties in substrate specificities, interacting protein partners, and inhibitors apart from QR1. We further hypothesize that QR2 is potentially a critical regulator, directly or indirectly, in the expression of antioxidant enzymes, such as catalase and glutathione reductases. Therefore, we propose to study the catalytic properties of QR2 with substrate specificity studies, especially the catalytic activity towards neurotoxic quinones and drug metabolites; inhibitor specificity studies; elucidation of QR2 structures in complex with its substrates and inhibitors; identification of interacting proteins by proteomics approach and potential in vivo electron-donors; and protein expression profiling of QR2 knockdown cell lines. The comprehensive approach will shed light on the unique catalytic properties and biological functions of QR2 and the understanding of QR2 polymorphism in relationship with certain neurological diseases, as QR2 polymorphism has been associated with idiopathic Parkinson's disease, schizophrenia, alcohol withdrawal symptoms and clozapine-induced aranulocytosis.