Genetic and Hormonal Regulation of Human CYP3A

描述（由申请人提供）：本补助金的总体目标 建议是确定遗传和激素因素， 人类CYP 3A表达的个体间差异。我们有 我们致力于CYP 3A的研究，因为它的核心作用， 在许多药物的代谢消除中，包括几种具有 有效和无毒的血药浓度范围狭窄。我们将测试 假设“人小肠中CYP 3A 4的稳态水平 主要由1，25-二羟基维生素D3信号通过 维生素D受体和CYP 3A 4 PXR反应元件”， 具体目标： 目标1.确定健康成人的肠道CYP 3A 4表型 与CYP 24表型共变，CYP 24是肠道VDR介导的 转录激活我们还将确定 肠道CYP 3A 4含量受肠道VDR mRNA含量调节， 血浆1，25-D3水平。 目标二。证明急性1，25-D3治疗可增加肠道CYP 3A 23 转录，1，25-D3替代疗法可以诱导 终末期肾病患者的CYP 3A 4转录活性 我们还将检验假设“A6981 G突变在 CYP 3A 5基因的内含子3控制肝和肠 CYP 3A 5，并影响某些CYP 3A药物底物的口服生物利用度” 具体目标如下： 目标3。表征并比较CYP 3A 4和CYP 3A 5依赖性内源性 使用异源表达的10种不同药物的代谢清除率 系统和CYP 3A表型分型的人肝和肠微粒体。此外，本发明还提供了一种方法， 我们将在健康的高加索人和非洲裔美国人中确定， CYP 3A 5 *1基因型成功预测平均较高的咪达唑仑 清除率高于纯合子CYP 3A 5 *3基因型受试者。我们 还将证明，对于非洲裔美国人，CYP 3A 5 *1基因剂量 对正确剪接的mRNA和CYP 3A 5蛋白在 十二指肠活检组织和体内咪达唑仑清除。 目标4。确定体内口服清除率的变异性是否 环孢霉素的部分决定于CYP 3A 5基因型。 如果所提出的假设得到验证， 用于窄型糖尿病个体化治疗的简单基因分型和表型试验 治疗指数药物，如环孢素。

DESCRIPTION (provided by applicant): The overall objective of this grant proposal is to identify the genetic and hormonal factors that define inter-individual differences in the expression of CYP3A in humans. We have directed our efforts to the study of CYP3A because of the central role that it has in the metabolic elimination of numerous drugs, including several with a narrow range of efficacious and nontoxic blood concentrations. We will test the hypothesis that "The steady-state level of CYP3A4 in the human small intestine is controlled primarily by 1,25-dihydroxy vitamin D3 signaling through the vitamin D receptor and the CYP3A4 PXR response element," with the following Specific Aims: Aim 1. Determine in healthy adults whether intestinal CYP3A4 phenotype co-varies with CYP24 phenotype, a reporter for intestinal VDR-mediated transcriptional activation. We will also determine whether variability in intestinal CYP3A4 content is regulated by intestinal VDR mRNA content and plasma 1,25-D3 level. Aim 2. Demonstrate that acute 1,25-D3 treatment increases intestinal CYP3A23 transcription in the rat, and that 1,25-D3 replacement therapy can induce CYP3A4 transcription activity in patients with end stage renal disease. We will also test the hypothesis that "Inheritance of an A6981G mutation within intron-3 of the CYP3A5 gene controls the expression of hepatic and intestinal CYP3A5, and influence the oral bioavailability of some CYP3A drug substrates" with the following Specific Aims: Aim 3. Characterize and compare the CYP3A4- and CYP3A5-dependent intrinsic metabolic clearance for 10 different drugs using a heterologous expression system and CYP3A-phenotyped human liver and intestinal microsomes. In addition, we will determine in healthy Caucasian and African-American adults whether the CYP3A5*1 genotype successfully predicts, on average, a higher midazolam clearances than that for subjects with the homozygous CYP3A5*3 genotype. We will also demonstrate that for African-Americans, there is a CYP3A5*1 gene-dose effect for the accumulation of properly spliced mRNA and CYP3A5 protein in duodenal biopsy tissue and for in vivo midazolam clearance. Aim 4. Determine whether variability in the in vivo oral clearance of cyclosporine is determined, in part, by the CYP3A5 genotype. If the proposed hypotheses are validated, it may become possible to develop simple genotyping and phenotyping tests for individualizing therapy with narrow therapeutic index drugs, such as cyclosporine.