Structure/Function Studies of Quinone Reductase 2

描述（由申请人提供）：拟议工作的目的是使用酶，结构，生化和生物学方法的组合来研究醌还原酶2 （QR2）的结构/功能关系。QR2的生物学功能仍然是几乎未知的，即使它的近亲，醌还原酶1 (QR1)，已经被很好地表征。我们最近的研究表明，醌还原酶2 （QR2）是许多天然多酚的潜在靶点，包括白藜芦醇类似物、黄酮类化合物、chalconoids和一些香豆素衍生物。QR2在CB1954的硝基和儿茶酚醌如肾上腺素的还原中也很活跃。通过RNAi方法敲低QR2进一步证明，白藜芦醇处理的细胞和QR2敲低的细胞表现出相似的特性：抗醌毒性，抗氧化酶表达增加，增殖率降低。基于这些研究，我们假设QR2与QR1在底物特异性、相互作用的蛋白伴侣和QR1以外的抑制剂方面具有非常不同的功能。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的催化特性，特别是对神经毒性醌类和药物代谢物的催化活性；抑制剂特异性研究；QR2配合物及其底物和抑制剂结构的研究蛋白质组学方法鉴定相互作用蛋白和潜在的体内电子供体QR2敲低细胞系的蛋白表达谱分析。该综合方法将揭示QR2独特的催化特性和生物学功能，以及QR2多态性与某些神经系统疾病的关系，因为QR2多态性与特发性帕金森病、精神分裂症、酒精戒断症状和氯氮平诱导的粒细胞缺乏症有关。

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.