Paraoxonases: Biomarkers of Susceptibility to Environmentally-Induced Disease

对氧磷酶：环境诱发疾病易感性的生物标志物

• 批准号: 7089370
• 负责人: LUCIO G COSTA
• 金额: $ 37.78万
• 依托单位: UNIVERSITY OF WASHINGTON
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-04-01 至 2009-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7089370
• 关键词: Parkinson' s disease; biomarker; carboxylic ester hydrolases; clinical research; detoxification; dopamine; embryo /fetus toxicology; environmental exposure; environmental toxicology; esterase; gene environment interaction; genetic polymorphism; genetic susceptibility; genetically modified animals; histopathology; human subject; isozymes; laboratory mouse; methylphenyltetrahydropyridine; neurotoxicology; neurotoxins; organophosphorus insecticide; oxidative stress; pharmacogenetics; protein localization; toxin metabolism

Paraoxonases (PON) belong to a family of enzymes coded by genes (PON1, PON2 and PON3) located on human chromosome 7. PON1 and PONS are synthesized in the liver and a portion of each is secreted into the serum in association with high density lipoprotein particles. PON1 hydrolyzes several organophosphorus (OP) compounds in addition to oxidized lipids and several drugs. PON1 displays several coding and regulatory region polymorphisms, which influence its catalytic efficiency and its level of expression. PON2 is a less studied PON that has two coding region polymorphisms, whose significance has not been yet established, and is widely distributed in tissues, including brain. PON2 does not hydrolyze OPs but has strong antioxidant properties. The overall goal of the proposed studies is to carry out a series of experiments that would add important knowledge on PON1 and PON2 functions and roles in determining susceptibility to environmentally-induced neurotoxicity and neurodegenerative diseases. Specific aims of the project are: 1)To investigate the roles of PON1 in modulating the toxicity resulting from exposure to mixtures of OP compounds. While previous studies have established and characterized the role of PON1 in determining susceptibility to individual OPs and their active metabolites (e.g. chlorpyrifos oxon, diazoxon, paraoxon), in a real-life situation exposure to multiple OPs usually occurs. The proposed studies, which will be carried out in PON1 knockout mice and in PON1 transgenic mice expressing one or the other of the two human PON192 alleles, will focus in particular on the contribution of PON1 and carboxylesterase (CarE) in modulating toxicity due to combined OP exposures. 2) To investigate the role of PON1 in modulating the developmental neurotoxicity of a specific OP (chlorpyrifos oxon) following prenatal exposure. Evidence is emerging that gestational exposure to OPs may have even more deleterious effects on the developing nervous system than postnatal exposure, underlying the importance of maternal PON1 status for protection of the fetus. Such studies will be carried out in PON1 transgenic mice and will include a series of biochemical, behavioral, histopathological and molecular end-points. 3) To investigate the role of PON1 and PON2 in Parkinson's disease (PD). As oxidative stress is believed to be a major contributor in the etiopathogenetic series of events leading to degeneration of dopaminergic neurons, and PON2 has strong antioxidant properties and is expressed in brain tissue, we will investigate whether PON2 knockout mice have increased susceptibility to a dopaminergic neurotoxin, MPTP. Studies aimed at localizing and examining PON2 levels in brain and at developing substrates for enzymatic assays will also be carried out. Finally, as a follow-up to our previous studies that examined only PON1 genotypes, PON1 status in PD patients will be determined, to understand whether PON1 may also play a role in PD. Indeed, our other studies on PON1 genetic variability and risk for carotid artery disease have shown that it is PON1 levels that determine risk and not any of the PON1 SNPs characterized to date.

对氧磷酶（PON）属于由位于人7号染色体上的基因（PON 1、PON 2和PON 3）编码的酶家族。PON1和脑桥在肝脏中合成，并且各自的一部分与高密度脂蛋白颗粒结合分泌到血清中。PON1除了水解氧化脂质和几种药物外，还水解几种有机磷（OP）化合物。PON1基因编码区和调控区的多态性影响其催化效率和表达水平。PON2是研究较少的PON，其具有两个编码区多态性，其意义尚未确定，并且被广泛地应用于临床。 分布在组织中，包括大脑。PON2不水解OP，但具有很强的抗氧化性能。拟议研究的总体目标是进行一系列实验，增加对PON1和PON2功能和作用的重要认识，以确定对环境诱导的神经毒性和神经退行性疾病的易感性。本项目的具体目标是：1）研究PON1在调节OP化合物混合物暴露引起的毒性中的作用。虽然以前的研究已经建立， 表征了PON1在确定对单个OP及其活性代谢物（例如毒死蜱、氧磷、二氮磷、对氧磷）的敏感性中的作用，在现实生活中，通常发生暴露于多种OP的情况。拟议的研究将在PON1基因敲除小鼠和表达两种人类PON192等位基因中的一种或另一种的PON1转基因小鼠中进行，将特别关注PON1和羧酸酯酶（CarE）在调节OP联合暴露所致毒性中的作用。2)目的探讨PON1在一种特异性毒死蜱（chlorpyrifos oxon）产前暴露后发育神经毒性的调节中的作用。 有证据表明，妊娠期暴露于OP可能对发育中的神经系统产生比出生后暴露更有害的影响，这说明母体PON1状态对保护胎儿的重要性。这些研究将在PON1转基因小鼠中进行，并将包括一系列生化、行为、组织病理学和分子终点。3)目的：探讨PON1和PON2在帕金森病（PD）发病中的作用。由于氧化应激被认为是导致多巴胺能神经元变性的一系列病因学事件的主要贡献者，并且PON2具有强的抗氧化特性并且在脑组织中表达，我们将研究PON2敲除小鼠是否具有 对多巴胺能神经毒素MPTP的敏感性增加。还将进行旨在定位和检查大脑中PON2水平以及开发酶测定底物的研究。最后，作为对我们先前仅检查PON1基因型的研究的随访，将确定PD患者的PON1状态，以了解PON1是否也可能在PD中发挥作用。事实上，我们对PON1遗传变异性和颈动脉疾病风险的其他研究表明，是PON1水平决定了风险，而不是迄今为止表征的任何PON1 SNP。