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：
8128597
负责人：
JOHN D SCHUETZ
金额：
$ 51.2万
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/8128597
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 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 prostaglandin transporter 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）：在上一个资金期间的研究旨在阐明ABC转运蛋白的功能和分子调节MRP4。目前的建议代表了这项工作的演变，基于我们开发的MRP4 - / - 小鼠的最新研究，并使用抗MRP4抗体，我们确定MRP4在睾丸中的人类和鼠Leydig细胞中都高度表达。由于Leydig细胞负责提供全身性睾丸激素，因此我们评估了MRP4 - / - 小鼠的血清睾丸激素水平，尽管睾丸激素不是MRP4的底物。我们发现，随着MRP4基因拷贝的减少，血清睾丸激素的相应降低与Leydig细胞中MRP4表达的降低直接相关。我们假设升高的前列腺素（PG）（已知的MRP4底物）可能是由于PG抑制睾丸激素合成而导致了这种效果的原因。负责形成PG的酶Cox-2在Leydig细胞中表达，COX-2抑制会增加全身睾丸激素水平。在成年MRP4 - / - 小鼠中，睾丸激素的水平恢复，MRP4 - / - 降低了PG水平。这些发现使我们假设在睾丸中，代偿途径在没有MRP4的情况下重新激活睾丸激素。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没有变化，但是一个编码已知结合PG（FABP4）的蛋白质的基因上调）。该模型系统中的这些发现具有人类相关性，因为化学治疗剂（例如伊马替尼，ganciclovir）和食物成分（多酚）抑制MRP4会导致睾丸激素和生殖作用急性减少。我们假设它们通过干扰MRP4转运产生这些效果。我们的体内模型将使我们能够直接测试它们如何损害睾丸激素的生物合成。这些发现提出了一种有趣的可能性，即在没有MRP4的情况下，可以在Leydig细胞中激活替代途径以恢复睾丸激素的生物合成。拟议的研究的目标是：i）阐明puberty后MRP4 - / - 小鼠如何达到正常睾丸激素水平； ii）确定MRP4 - / - 与MRP4 +/ +是否有改变的分化状态； iii）评估脂肪酸结合蛋白4（FabP4）（一种已知结合Pg的蛋白质）在模型系统中调节睾丸激素生物合成中的作用； iv）确定通过干扰MRP4功能的化学治疗剂和已知改变睾丸激素水平的化学治疗剂和异种生物。提出的研究得到了MRP4 - / - 和MRP4+/+小鼠的初步数据的支持，并且具有直接的人类相关性。公共卫生相关性：许多药物和异种生物可以改变睾丸激素水平，从而导致不良影响。我们已经使用遗传模型系统来识别调节睾丸激素水平的新型运输系统。我们的研究具有直接的人类相关性，因为异种生物和药物干扰该运输系统可能会造成人类睾丸激素水平的降低。这些研究可能会导致治疗方法，以防止这种不幸的副作用。