The Role of Cyp2b in Toxicant Metabolism and Sensitivity

Cyp2b 在毒物代谢和敏感性中的作用

• 批准号: 8367031
• 负责人: William S Baldwin
• 金额: $ 36.31万
• 依托单位: CLEMSON UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8367031
• 关键词: Animals; Bile Acids; CYP2B6 gene; Chemicals; Chronic; Clinical; Corn Oil; Cytochromes; Data; Deposition; Development; Diet; Disease; Drug Metabolic Detoxication; Environmental Pollutants; Enzymes; Family; Fatty Liver; Fatty acid glycerol esters; Gender; Genetic Polymorphism; Grant; Hispanics; Histopathology; Homeostasis; Hormones; In Vitro; Individual; Injection of therapeutic agent; Knock-out; Knockout Mice; Laboratories; Lead; Lipids; Liver; Mediating; Metabolic Diseases; Metabolism; Microsomes; Modeling; Mus; Mutation; Nervous system structure; Obesity; Parathion; Pesticides; Pharmaceutical Preparations; Pharmacologic Substance; Plasticizers; Play; Proteins; Protocols documentation; RNA Interference; Reaction; Recombinants; Repression; Role; Steroids; Substrate Specificity; Symptoms; Tandem Repeat Sequences; Testing; Toxic Environmental Substances; Toxic effect; Transgenic Mice; United States Food and Drug Administration; Unsaturated Fatty Acids; Wild Type Mouse; Work; Xenobiotic Metabolism; Xenobiotics; drug metabolism; environmental chemical; forgetting; gene environment interaction; human CYP2B6 protein; in vivo; inhibitor/antagonist; member; mouse model; nonylphenol; novel; promoter; small hairpin RNA; toxicant

DESCRIPTION (provided by applicant): The cytochrome P450s (CYPs) are key enzymes involved in the detoxification of numerous chemicals including steroids, bile acids, pharmaceuticals, and environmental chemicals. Cyp2b is considered the forgotten CYP because not as much is known about its substrate specificity, it is expressed at lower levels in the liver than some other detoxification CYPs, and the FDA does not mandate the use of recombinant Cyp2b in drug metabolism testing. However, Cyp2b is highly inducible, highly polymorphic, gender predominant, and recent work shows it is expressed at higher levels than once thought, especially in hispanics. We will investigate the role of this CYP in the metabolism of environmental toxicants, determine whether individuals with low Cyp2b are sensitive to specific toxicants that are Cyp2b substrates, and evaluate whether CYP inhibition by toxicants could potentially lead to metabolic disorders such as obesity. We have recently developed a Cyp2b-knockdown mouse using RNAi that represses the expression of all five murine Cyp2b members. These mice demonstrate lower Cyp2b protein and activity and TCPOBOP the potent Cyp2b inducer is unable to out-compete the shRNA-mediated repression. In aim 1, we will use this mouse model to estimate Cyp2b metabolism using microsomes from untreated and TCPOBOP-treated wild-type and Cyp2b-KD mice. In aim 2, we will test whether Cyp2b-KD mice are susceptible to specific toxicants such as nonylphenol or parathion that are metabolized by Cyp2b. Last, recent preliminary data following ip injections with TCPOBOP or corn oil as a carrier revealed that Cyp2b-KD mice but not wild-type mice are unable to properly depurate the unsaturated fatty acids from the liver. This suggests an important role for Cyp2b in lipid homeostasis. In aim 3, we will test whether mice with low Cyp2b activity are susceptible to high-fat diet (Western diet) induced hepatic steatosis (fatty liver) and obesity. If Cyp2b-KD mice are susceptible to obesity, this would suggest that Cyp2b inhibitors may act as environmental obesogens. Overall, the purpose of this project is determine the role of Cyp2b in the metabolism, fate, and toxic effects of environmental toxicants in vivo using a novel murine model recently developed in our laboratory. PUBLIC HEALTH RELEVANCE: The cytochrome P450s (CYPs) are key enzymes involved in the detoxification of numerous chemicals including steroids, bile acids, pharmaceuticals, and environmental chemicals. Cyp2b is considered the forgotten CYP because it is expressed at lower levels in the liver than some other detoxification CYPs. However, it is highly inducible and recent work shows it is expressed at higher levels than once thought. We will investigate the role of this CYP in the metabolism of environmental toxicants, determine whether individuals with low Cyp2b are sensitive to specific toxicants, and evaluate whether CYP inhibition by toxicants could potentially lead to metabolic disorders.

描述（由申请人提供）：细胞色素P450（CYP）是参与多种化学品（包括类固醇、胆汁酸、药物和环境化学品）解毒的关键酶。Cyp 2b被认为是被遗忘的酶，因为对它的底物特异性知之甚少，它在肝脏中的表达水平低于其他一些解毒CYP，并且FDA没有强制要求在药物代谢测试中使用重组Cyp 2b。然而，Cyp 2b是高度可诱导的，高度多态性，性别占主导地位，最近的工作表明，它的表达水平比以前认为的要高，特别是在西班牙裔人中。我们将研究这种代谢酶在环境毒物代谢中的作用，确定Cyp 2b低的个体是否对Cyp 2b底物的特定毒物敏感，并评估毒物的代谢酶抑制是否可能导致代谢紊乱，如肥胖。我们最近开发了一个Cyp 2b敲低小鼠使用RNAi抑制所有五个鼠Cyp 2b成员的表达。这些小鼠表现出较低的Cyp 2b蛋白和活性，并且有效的Cyp 2b诱导剂TCPOBOP不能竞争过shRNA介导的抑制。在目标1中，我们将使用该小鼠模型，使用来自未处理和TCPOBOP处理的野生型和Cyp 2b-KD小鼠的微粒体来估计Cyp 2b代谢。在目标2中，我们将测试Cyp 2b-KD小鼠是否对由Cyp 2b代谢的特定毒物如壬基酚或二氯二磷敏感。最后，在用TCPOBOP或玉米油作为载体ip注射后的最近初步数据显示Cyp 2b-KD小鼠而不是野生型小鼠不能从肝脏适当地净化不饱和脂肪酸。这表明Cyp 2b在脂质稳态中的重要作用。在目标3中，我们将测试具有低Cyp 2b活性的小鼠是否易受高脂肪饮食（西方饮食）诱导的肝脂肪变性（脂肪肝）和肥胖症的影响。如果Cyp 2b-KD小鼠易患肥胖症，这将表明Cyp 2b抑制剂可能作为环境致肥胖剂。总的来说，本项目的目的是确定Cyp 2b在体内环境毒物的代谢，命运和毒性效应中的作用，使用我们实验室最近开发的一种新型小鼠模型。 公共卫生相关性：细胞色素P450（CYP）是参与许多化学物质（包括类固醇、胆汁酸、药物和环境化学物质）解毒的关键酶。Cyp 2b被认为是被遗忘的蛋白质，因为它在肝脏中的表达水平低于其他一些解毒CYP。然而，它是高度可诱导的，最近的工作表明它的表达水平比以前认为的要高。我们将研究这种蛋白质在环境毒物代谢中的作用，确定Cyp 2b低的个体是否对特定毒物敏感，并评估毒物对蛋白质的抑制是否可能导致代谢紊乱。