INTERACTIONS OF P GLYCOPROTEIN WITH CYTOCHROME P4503A

描述(摘自申请者摘要)：人细胞色素P4503A 代谢多种治疗药物，激活环境 外源物质，并由药物和杀虫剂诱发。因为有 细胞色素P3A基础和诱导性表达的个体间差异很大 这会影响治疗结果，并可作为易感标志物 对于环境原因引起的疾病，调节细胞色素P3A的因素有 正在进行严密的调查。我们最近的研究表明， 多药耐药基因(MDR1)的产物，药物外排转运体 P-糖蛋白(Pgp)，影响药物的药理作用。 利福平是利福平治疗程度的主要决定因素 诱导细胞色素P4503A(CyP3A)。因为PGP运送类固醇和 其他结构不同的外源化合物，即细胞色素P3A底物和 诱导者，这笔赠款将扩展我们最近的研究，以检验假设1，即 Pgp是基础CyP3A表达和CyP3A大小的决定因素 被许多其他结构上无关的外来物诱导。药效 将在两个模型系统中分析CyP3A的处置和药物诱导， 高表达人多药耐药基因Pgp的体外系统(LS180细胞) 体内系统缺乏mdr1a/1b/pgp(mdr1a/lb(-/-)小鼠)。这个 小鼠和人MDR/Pgp转运某些CYP3A诱导剂的能力 之前被证明是PGP的底物也将进行测试。至 最大限度地利用mdrla/1b基因敲除小鼠和其他小鼠 转基因模型，这项资助将表征细胞色素P3A免疫反应 小鼠肝脏中具有代表性的细胞色素P3A活性的蛋白质和细胞色素P3A的mRNAs。 假设2将检验Pgp是否通过影响细胞内 细胞色素P3A底物的浓度，是一个决定因素的程度 细胞色素P3A--细胞内形成的代谢物，以及PGP是否转运细胞色素P3A 产生代谢物。这一目标使用了我们的新型细胞系，它们形成了 培养的极化上皮并稳定表达功能性细胞色素P3A4和 PGP。总而言之，这笔赠款将探索相互作用的性质 共同膜水平的细胞色素P3A底物和诱导剂 转运蛋白、Pgp以及这些Pgp相互作用对细胞色素P3A的影响 介导的代谢和细胞色素P3A的诱导反应。

DESCRIPTION (Adapted from Applicant's Abstract): Human cytochromes P4503A metabolize numerous therapeutic agents, bioactivate environmental xenobiotics, and are induced by drugs and pesticides. Because there is large interindividual variation in basal and inducible expression of CYP3A that affects therapeutic outcome and could serve as a susceptibility marker for environmentally caused diseases, the factors which regulate CYP3A are under intense investigation. Our recent studies have established that the product of the multidrug resistance gene (MDR1), the drug efflux transporter P-glycoprotein (Pgp), influences the pharmacological disposition of rifampicin and is a major determinant of the extent to which rifampicin induces cytochrome P4503A (CYP3A). Because Pgp transports steroids and other structurally diverse xenobiotics that are CYP3A substrates and inducers, this grant will extend our recent study to test hypothesis 1, that Pgp is a determinant of basal CYP3A expression and the magnitude of CYP3A induction by many other structurally unrelated xenobiotics. Drug disposition and drug-induction of CYP3A will analyzed in two model systems, an in vitro system (LS180 cells) in which human MDR1 Pgp is overexpressed and an in vivo system that lacks mdr1a/1b/Pgp (mdrla/lb (-/-) mice). The capabilities of mouse and human MDR/Pgp to transport some CYP3A inducers not previously demonstrated to be Pgp substrates will also be tested. To maximally capitalize on the mdrla/1b knockout mice and on other murine transgenic models, this grant will characterize CYP3A immunoreactive proteins, a representative CYP3A activity and CYP3A mRNAs in mouse liver. Hypothesis 2 will test whether Pgp, by influencing the intracellular concentration of CYP3A substrates, is a determinant of the extent of CYP3A-metabolites formed in the cell, and whether Pgp transports CYP3A generated metabolites. This aim uses our novel cell lines which form polarized epithelium in culture and stably express functional CYP3A4 and Pgp. In total, this grant will explore the nature of the interaction between CYP3A substrates and inducers at the level of their common membrane transporter, Pgp, and the ramifications of these Pgp interactions on CYP3A mediated metabolism and the CYP3A inductive response.