Regulation of Hepatic Excretion of Xenobiotics by Mrps

Mrps 对异生物质肝脏排泄的调节

基本信息

批准号：
7664341
负责人：
CURTIS DEAN KLAASSEN
金额：
$ 33.22万
依托单位：
UNIVERSITY OF KANSAS MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2000
资助国家：
美国
起止时间：
2000-08-10 至 2011-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7664341
关键词：
5&apos Flanking Region Anions Applications Grants Arts Bile Acids Biliary Binding Biological Assay Cell Nucleus Cells Chemoprotective Agent Computer Simulation DNA Sequence Data Drug Interactions Drug Transport Enzymes Excretory function Extrahepatic Cholestasis Family GCLC gene GCLM gene Gene Targeting Genes Genetic Transcription Glutamate-Cysteine Ligase Glutathione Goals Hepatic Hepatocyte In Vitro Injury Knock-out Knockout Mice Ligation Liver Mediating Metabolic Biotransformation Methodology Modeling Molecular Multidrug Resistance-Associated Proteins Mus NAD(P)H dehydrogenase (quinone) 1, human Nuclear Nucleic Acid Regulatory Sequences Pharmaceutical Preparations Phase Play Process Promoter Regions Proteins Rattus Regulation Reporter Genes Resistance Response Elements Role Serum Specificity Surgical Models Testing Toxicology Trans-Activators Transcript Transcriptional Regulation Transport Process Up-Regulation Wild Type Mouse Xenobiotics basolateral membrane bile duct cancer chemoprevention cytotoxic deletion analysis detoxication environmental chemical heme oxygenase-1 in vivo insight liver function mRNA Expression member mouse model neoplastic cell novel promoter research study transcription factor

项目摘要

DESCRIPTION (provided by applicant): Multidrug resistance-associated proteins (Mrps) play a key role in hepatic detoxication by transporting Phase-ll conjugates and other organic compounds out of hepatocytes. Similarly, upregulation of Mrps in tumor cells confers resistance to chemotherapeutic drugs by transporting these cytotoxic compounds out of cells. The regulatory mechanisms governing Mrp expression in normal and diseased liver, and in tumor cells, are not understood. Thus, the overall goal of this application is to study the molecular mechanisms of transcriptional regulation of Mrps. Nuclear factor E2 related-factor 2 (Nrf2) is emerging as a critical transcription factor in regulation of both constitutive and inducible expression of Phase-ll enzymes. Because Mrps play a key role in the efflux of Phase-ll conjugates, we hypothesize that Mrps are coordinately regulated with Phase-ll enzymes by Nrf2. We recently examined Mrp expression in three different models: 1) mice treated with monofunctional inducers that selectively upregulate Phase-ll enzymes, 2) bile-duct ligation, a surgical model of extrahepatic cholestasis, and 3) mice with targeted disruption of glutathione synthesis. In each model, induction of Mrps and classical Nrf2 target genes was observed. Moreover, using in-silico analysis, we identified putative Nrf2-responsive sequences, known as electrophile response elements (EpREs), in the 5' flanking regions of the Mrp2, 3, and 4 genes. We hypothesize that activation and subsequent binding of Nrf2 to these EpREs results in increased expression of Mrp2, 3, and 4. Thus we propose Mrps belong to the battery of Nrf2-regulated detoxication genes. To test this hypothesis, we will determine: 1) the role of Nrf2 in Mrp induction in mice, taking advantage of Nrf2-null mice, 2) Nrf2 activation and subsequent translocation to the nucleus, 3) critical response elements by in vitro and in vivo reporter gene assay in combination with promoter deletion analysis, 4) Nrf2 binding to EpREs identified in Mrp 5' flanking regions, and 5) specificity of Nrf2 binding to Mrp promoter regions. Data from the experiments in this proposal will provide novel insight into the transcriptional regulation of Mrps. Elucidation of the role of Nrf2 in the regulation of the efflux transport process will have significant ramifications in toxicology, xenobiotics disposition, drug-drug interaction, and cancer chemoprevention.

描述（由申请人提供）：多药抗性相关蛋白（MRP）通过从肝细胞中将相ll偶联物和其他有机化合物传输出来，在肝解毒中起关键作用。同样，肿瘤细胞中MRP的上调通过将这些细胞毒性化合物从细胞中输送出来，赋予对化学治疗药物的耐药性。尚不清楚控制正常和患病肝脏以及肿瘤细胞中MRP表达的调节机制。因此，该应用的总体目标是研究MRP的转录调控的分子机制。核因子E2相关因素2（NRF2）在调节相位ll酶的组成型和诱导表达的调节方面是临界转录因子。由于MRP在相结合物的外排起关键作用，因此我们假设MRP通过NRF2协调与相ll酶协调。我们最近检查了三种不同模型中的MRP表达：1）用单功能诱导剂治疗的小鼠有选择地上调相位ll酶，2）胆管连接，肝外胆汁淤积的手术模型以及3）靶向破坏谷胱甘肽合成的小鼠。在每个模型中，观察到MRP和经典NRF2靶基因的诱导。此外，使用硅内分析，我们在MRP2、3和4个基因的5'侧翼区域中确定了推定的NRF2响应序列，称为电力反应元件（EPRES）。我们假设NRF2与这些EPRES的激活和后续结合导致MRP2，3和4的表达增加。因此，我们提出MRP属于NRF2调节的解毒基因的电池。要检验该假设，我们将确定：1）NRF2在小鼠中NRF2在MRP诱导中的作用，利用NRF2-NULL小鼠，2）NRF2激活，随后转移至核的迁移，3）体外和体外和In In In In In In In In In In In In In In In In In In In In In In In In In MR分析中NRF2的作用，3）NRF2的关键响应元件，4）区域和5）NRF2与MRP启动子区域结合的特异性。该提案中实验的数据将为MRP的转录调控提供新的见解。阐明NRF2在调节外排运输过程中的作用将在毒理学，异种生物处理，药物 - 药物相互作用和癌症化学预防方面具有显着影响。