MRP4 in Drug Sensitivity and Physiology

MRP4 在药物敏感性和生理学中的应用

基本信息

批准号：
7912851
负责人：
JOHN D SCHUETZ
金额：
$ 51.73万
依托单位：
ST. JUDE CHILDREN'S RESEARCH HOSPITAL
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：
2000-04-01 至 2013-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7912851
关键词：
6-Mercaptopurine ATP-Binding Cassette Transporters Abbreviations Accounting Acute Adult Adverse effects Affect Aging Anabolism Androgens Animal Model Animals Antibodies Arachidonic Acids Bile Acids Binding Biological Models Biological Process Biology Blood - brain barrier anatomy Brain CCL21 gene Cell Maturation Cell physiology Cholestasis Data Defect Development Disease Electron Microscopy Enzymes Evolution Feedback Figs - dietary Food Funding Gametogenesis Ganciclovir Gene Expression Genes Genetic Models Germ Cells Goals Gynecomastia Health Hepatic Homeostasis Hormones Human Hydroxysteroid Dehydrogenases Imatinib Immunoassay Integrin alpha6 Knock-out Knockout Mice Knowledge Laboratory Study Lead Left Link Metabolism Microarray Analysis Mixed Function Oxygenases Modeling Molecular Mus P-Glycoproteins PDGFRB gene PTGS2 gene Pathway interactions Pattern Pharmaceutical Preparations Physiological Physiology Platelet-Derived Growth Factor Receptor Play Population Predisposition Process Production Prostaglandin-Endoperoxide Synthase Prostaglandins Proteins Puberty Recovery Regulation Role Seminiferous tubule structure Series Serum Side Source Stem cells System Testing Testis Testosterone Therapeutic Toxic effect Up-Regulation Variant Work Xenobiotics arachidonate base chemotherapeutic agent cytotoxic drug sensitivity fatty acid-binding proteins human FABP4 protein in vivo in vivo Model insight leydig interstitial cell male novel polyphenol prevent progesterone 11-hemisuccinate-(2-iodohistamine)prostaglandin transporter public health relevance reproductive solute testosterone biosynthesis thiopurine

项目摘要

DESCRIPTION (provided by applicant): Studies over the last funding period were directed to elucidating the function and molecular regulation of the ABC transporter, Mrp4. The current proposal represents an evolution of this work, based upon recent studies from this laboratory using the Mrp4-/- mouse we developed, and using our anti-Mrp4 antibodies, we determined that Mrp4 is highly expressed in both human and murine Leydig cells in the testes. As the Leydig cells are responsible for supplying systemic testosterone we evaluated the Mrp4-/- mice for serum levels of testosterone despite the fact that testosterone is not a substrate for Mrp4. We found that as Mrp4 gene copy decreases there are corresponding reductions in serum testosterone that are directly associated with reduced expression of Mrp4 in Leydig cells. We hypothesized that elevated prostaglandins (PG) (a known Mrp4 substrate) might be responsible for this effect because PG inhibit testosterone synthesis. The enzyme responsible for formation of PG, COX-2 is expressed in Leydig cells and COX-2 inhibition increases systemic testosterone levels. In adult Mrp4-/- mice the level of testosterone is restored and PG levels are reduce in the Mrp4-/-. These findings led us to hypothesize that, in the testes, compensatory pathways re-activated testosterone synthesis in the absence of Mrp4. Our preliminary data shows, in testes, upregulation of genes directly linked to PG metabolism (although COX-2 is unchanged, however one gene encoding a protein known to bind PG (FABP4) is upregulated). These findings in this model system are of human relevance because chemotherapeutic agents (e.g., imatinib, ganciclovir) and food components (polyphenols) that inhibit Mrp4 cause acute reduction in testosterone and reproductive effects. We hypothesize they produce these effects by interfering with Mrp4 transport. Our in vivo model will allow us to directly test how they impair testosterone biosynthesis. These findings raise the intriguing possibility that, in the absence of Mrp4, alternate pathways can be activated in Leydig cells to restore testosterone biosynthesis. The objectives of the proposed studies are to: i) to elucidate how post-puberty Mrp4-/- mice achieve normal testosterone levels; ii) determine if Mrp4-/- vs. Mrp4 +/+ have altered differentiation status; iii) evaluate the role of fatty-acid binding protein 4 (FABP4), a protein known to bind PG, in regulating testosterone biosynthesis in model systems; iv) determine if chemotherapeutic agents and xenobiotics known to alter testosterone levels do so by interfering with Mrp4 function. The proposed studies are supported by preliminary data from the Mrp4-/- and Mrp4+/+ mice and are of direct human relevance. PUBLIC HEALTH RELEVANCE: A number of drugs and xenobiotics can alter testosterone levels leading to untoward effects. We have used a genetic model system to identify a novel transport system that regulates testosterone levels. Our studies are of direct human relevance because xenobiotic and drug interference with this transport system may account for reduced testosterone levels in humans. These studies may lead to therapeutic approaches to prevent this unfortunate side effect.

描述（由申请人提供）：上一个资助期的研究旨在阐明 ABC 转运蛋白 Mrp4 的功能和分子调控。当前的提案代表了这项工作的演变，基于该实验室最近使用我们开发的 Mrp4-/- 小鼠进行的研究，并使用我们的抗 Mrp4 抗体，我们确定 Mrp4 在人类和小鼠 Leydig 细胞中高度表达睾丸。由于 Leydig 细胞负责供应全身睾酮，因此我们评估了 Mrp4-/- 小鼠的血清睾酮水平，尽管事实上睾酮不是 Mrp4 的底物。我们发现，随着 Mrp4 基因拷贝的减少，血清睾酮也会相应减少，这与 Leydig 细胞中 Mrp4 表达的减少直接相关。我们假设升高的前列腺素 (PG)（一种已知的 Mrp4 底物）可能是造成这种效应的原因，因为 PG 会抑制睾酮合成。负责形成 PG 的酶 COX-2 在 Leydig 细胞中表达，抑制 COX-2 会增加全身睾酮水平。在成年 Mrp4-/- 小鼠中，Mrp4-/- 的睾酮水平得到恢复，PG 水平降低。这些发现使我们推测，在睾丸中，在缺乏 Mrp4 的情况下，补偿途径会重新激活睾酮合成。我们的初步数据显示，在睾丸中，与 PG 代谢直接相关的基因上调（尽管 COX-2 未改变，但编码已知结合 PG 的蛋白质 (FABP4) 的一个基因上调）。该模型系统中的这些发现与人类相关，因为抑制 Mrp4 的化疗药物（例如伊马替尼、更昔洛韦）和食物成分（多酚）会导致睾酮和生殖效应急剧减少。我们假设它们通过干扰 Mrp4 运输来产生这些效应。我们的体内模型将使我们能够直接测试它们如何损害睾酮生物合成。这些发现提出了一个有趣的可能性，即在缺乏 Mrp4 的情况下，间质细胞中可以激活替代途径以恢复睾酮生物合成。拟议研究的目的是： i) 阐明青春期后 Mrp4-/- 小鼠如何达到正常的睾酮水平； ii)确定Mrp4-/-与Mrp4+/+相比是否改变了分化状态； iii) 评估脂肪酸结合蛋白 4 (FABP4)（一种已知结合 PG 的蛋白质）在调节模型系统中睾酮生物合成中的作用； iv) 确定已知可改变睾酮水平的化疗药物和异生素是否通过干扰 Mrp4 功能来实现这一目的。拟议的研究得到了来自 Mrp4-/- 和 Mrp4+/+ 小鼠的初步数据的支持，并且与人类直接相关。公共卫生相关性：许多药物和异生素可以改变睾酮水平，导致不良影响。我们使用遗传模型系统来识别调节睾酮水平的新型运输系统。我们的研究与人类直接相关，因为外源物质和药物对这种运输系统的干扰可能会导致人类睾酮水平降低。这些研究可能会带来预防这种不幸副作用的治疗方法。