The Role of Cyp2b in Toxicant Metabolism and Sensitivity

Cyp2b 在毒物代谢和敏感性中的作用

基本信息

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
项目类别：
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

项目摘要

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。 Cyp2b 被认为是被遗忘的 CYP，因为人们对它的底物特异性知之甚少，它在肝脏中的表达水平比其他一些解毒 CYP 低，而且 FDA 不强制要求在药物代谢测试中使用重组 Cyp2b。然而，Cyp2b 具有高度诱导性、高度多态性、性别主导性，最近的研究表明它的表达水平比以前想象的要高，尤其是在西班牙裔中。我们将研究这种 CYP 在环境毒物代谢中的作用，确定 Cyp2b 水平低的个体是否对作为 Cyp2b 底物的特定毒物敏感，并评估毒物对 CYP 的抑制是否可能导致肥胖等代谢紊乱。我们最近使用 RNAi 开发了一种 Cyp2b 敲低小鼠，可抑制所有 5 个小鼠 Cyp2b 成员的表达。这些小鼠表现出较低的 Cyp2b 蛋白和活性，并且 TCPOBOP（有效的 Cyp2b 诱导剂）无法胜过 shRNA 介导的抑制。在目标 1 中，我们将使用该小鼠模型，使用未经处理和 TCPOBOP 处理的野生型和 Cyp2b-KD 小鼠的微粒体来估计 Cyp2b 代谢。在目标 2 中，我们将测试 Cyp2b-KD 小鼠是否对 Cyp2b 代谢的特定毒物（例如壬基酚或对硫磷）敏感。最后，以 TCPOBOP 或玉米油作为载体进行腹腔注射后的最新初步数据显示，Cyp2b-KD 小鼠（而非野生型小鼠）无法从肝脏中正确纯化不饱和脂肪酸。这表明 Cyp2b 在脂质稳态中发挥着重要作用。在目标3中，我们将测试Cyp2b活性低的小鼠是否容易受到高脂肪饮食（西方饮食）诱导的肝脂肪变性（脂肪肝）和肥胖的影响。如果 Cyp2b-KD 小鼠容易肥胖，这表明 Cyp2b 抑制剂可能充当环境致肥胖剂。总体而言，该项目的目的是使用我们实验室最近开发的新型小鼠模型确定 Cyp2b 在体内环境毒物的代谢、命运和毒性作用中的作用。公共健康相关性：细胞色素 P450 (CYP) 是参与多种化学物质（包括类固醇、胆汁酸、药物和环境化学物质）解毒的关键酶。 Cyp2b 被认为是被遗忘的 CYP，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，最近的研究表明它的表达水平比以前想象的要高。我们将研究这种 CYP 在环境毒物代谢中的作用，确定 Cyp2b 低的个体是否对特定毒物敏感，并评估毒物对 CYP 的抑制是否可能导致代谢紊乱。