Developmental exposure to Bisphenol A and susceptibility to liver injury

 说明(申请人提供)：肝脏通过肝脏生物转化和胆汁排泄，使体内的化学物质和药物排出体内。三磷酸腺苷结合盒，C亚家族，成员2(ABCC2，又名MRP2)，是一种膜结合的外排转运体，将有机阴离子从肝细胞转运到胆汁中，在这一过程中发挥着关键作用。许多环境化学品、药物和内源性代谢物是ABCC2的底物。ABCC2功能的破坏会导致胆汁流动中断、药物处置和药物所致的肝损伤。我们将利用双酚A(BPA)，一种塑料成分，作为一种工具，了解早期接触如何影响以后生活中的肝脏胆汁排泄。我们的数据显示，孕期接触双酚A和 哺乳期通过增加组蛋白脱乙酰酶2(HDAC2)和减少小鼠ABCC2启动子上的乙酰化组蛋白H3，降低了135日龄成年雄性断奶后没有暴露于双酚A的成年雄性ABCC2的表达和肝功能。在这项建议中，我们试图询问我们观察到的双酚A暴露对肝脏是否有毒理学后果，并更好地了解ABCC2和HDAC2表达/功能的调节是否可以恢复所观察到的胆汁排泄量的减少。我们假设，BPA暴露通过HDAC2和Nrf2依赖的机制下调ABCC2启动子的活性，从而降低胆汁中的表达。观察到的胆汁排泄量的减少增加了对胆汁排泄过程中的肝脏毒物的易感性。具体目标1将表征ABCC2在围产期暴露于BPA后成人肝脏排泄中的作用。首先，我们将测试在成年雄性后代中恢复ABCC2蛋白表达是否会恢复观察到的由发育中的双酚A暴露引起的胆汁排泄量的减少。接下来，我们将测试围产期接触双酚A是否会改变成年雄性后代对肝脏毒物引起的肝损伤的易感性。特异性目标2将表征NRF2和组蛋白脱乙酰酶2是否能增加Abcc2的表达并恢复胆汁排泄。我们的双酚A暴露模型表明，双酚A增加了小鼠ABCC2启动子上的HDAC2关联。我们将通过遗传学和药理学方法进一步确定HDAC2是否是该模型中ABCC2表达的调节器，以及强制表达NRF2是否可以恢复ABCC2的表达和胆汁流量。结果：这项工作将显著影响肝脏健康领域-证明：1)通过ABCC2的肝脏胆道功能容易受到化学物质暴露的“重新编程”，2)生命早期暴露改变了对晚年肝脏损伤的易感性，)确定HDAC2是恢复胆汁流动的潜在靶点。地区影响：该项目将为本科生提供良好的智力和技术培训环境，并增强罗德岛大学的研究能力。

 DESCRIPTION (provided by applicant): Hepatic detoxification of chemicals and drugs from the body is accomplished by the hepatocytes via hepatic biotransformation and biliary excretion. ATP-binding cassette, sub-family C (CFTR/MRP), member 2 (ABCC2, aka MRP2), is a membrane-bound efflux transporter that transports organic anions out of the hepatocytes and into bile, playing critical role in this process. Numerous environmental chemicals, drugs, and endogenous metabolites are ABCC2 substrates. Disruption of ABCC2 function leads to disrupted bile flow, drug disposition, and drug-induced liver injury. We will be utilizing bispheno A (BPA), a plastics component, as a tool to understand how early life exposure to affects hepatic biliary excretion later in life. Our data illustrate that BPA exposure during gestation and lactation decreased liver ABCC2 expression and hepatic function of adult males that were >135 days old, which had no BPA exposure after weaning via increased histone deacetylase 2 (Hdac2) and decreased acetylated Histone H3 at the mouse ABCC2 promoter. In this proposal, we seek to ask whether our observation with BPA exposure has a toxicological consequence to liver and better understand whether modulation of ABCC2 and Hdac2 expression/function can restore the observed decrease in biliary excretion. We hypothesize that BPA exposure decreases biliary expression via down regulation of ABCC2 promoter activity via Hdac2 and Nrf2-dependent mechanisms. The observed decrease in biliary excretion increases susceptibility to hepatotoxicants that undergo biliary excretion. Specific Aim 1 will characterize the role of ABCC2 in adult liver excretion after perinatal BPA exposure. First, we will test whether restoration of ABCC2 protein expression in adult male progeny will restore the observed decrease in biliary excretion caused by developmental BPA exposure. We will next test whether perinatal BPA exposure alters susceptibility of adult male progeny to liver injury induced by hepatotoxicants. Specific Aim 2 will characterize whether of NRF2 and histone deacetylase 2 increase Abcc2 expression and can restore biliary excretion. Our BPA exposure model elucidated that BPA increases Hdac2 association at the mouse ABCC2 promoter. We will further determine whether Hdac2 is a modulator of ABCC2 expression in this model through genetic and pharmacological approaches and whether forced expression of NRF2 can restore ABCC2 expression and bile flow. Outcome: This work will significantly impact the field of liver health - demonstrating: 1) hepatic biliary function via ABCC2 is susceptible to "reprogramming" by chemical exposure, 2) early life exposure changes susceptibility to liver injury later in life, ) Identify Hdac2 as a potential target to restore bile flow. AREA impact: This project will provide an excellent intellectual and technical training environment for undergraduates and enhance the research capacity at the University of Rhode Island.