CYP1A1 GENE AND ENVIRONMENTAL TOXICITY

描述(摘自申请者摘要)：该项目的长期目标 项目是了解SYP1A1(细胞色素P1-450)所起的作用 环境污染物造成的毒性。Cyp1a1是 二恶英诱导电池，其基因被上调 通过Ah受体(AHR)。CYP1A1酶的氧化产物卤代和 多环芳香族碳氢化合物，例如多氯联苯 和苯并[a]芘(BaP)。AHR配体包括二恶英(这是 代谢极慢)和多氯联苯和苯并(BaP)(代谢 更快)。[ah]电池在铅的毒性中起主要作用。 皮肤、骨髓、肝脏、眼睛、卵巢和免疫系统--以及 致癌。BaP在小鼠体内的给药剂量和给药途径 是靶器官毒性的重要决定因素。遗传 BaP毒性的差异取决于高亲和力C57BL/6型 (AHR(B)等位基因)或低亲和力DBA/2型(Ahr(D)等位基因) 受体。小鼠细胞色素P1A1基因表达呈结构性低表达， 但在几乎每一种组织和细胞类型中都高度诱导 身体--在接触多环芳香化学品后。毒性可以 发生于新陈代谢或受体依赖(新陈代谢- 独立)机制。这个实验室最近在 制造Ahr(-/-)基因敲除小鼠品系。探讨其作用机制 CYP1A1代谢介导的毒性与AHR介导的毒性的比较 因此，我们建议： [1]开发常规的和可诱导的Cypla(-/-) 基因敲除转基因小鼠品系； [2]开发(全球的，而不是特定于组织的)Cyp1a1(u/u) (超表达)转基因小鼠系，然后产生，通过 选育Cyp1a1(-/-)Ahr(-/-)、Cyp1a1 (-/-)AHRD/d)、Cyp1a1(-/-)Ahr(b/b)、Cyp1a1(u/u)Ahr(-/-)、 Cyp1a1(u/u)Ahr(d/d)和Cyp1a1(u/u)Ahr(b/b)。 [3]研究骨髓毒性和皮肤炎症，如下 口服BaP和外用BaP对这些小鼠系的治疗作用 7，12-二甲基苯并[a]菲(DMBA)分别测定 哪些形式的环境毒性依赖于细胞色素P1A1 新陈代谢，以及哪些形式的毒性取决于啊 受体。 这些研究将极大地加深我们对CYP1A1的理解 与AHR依赖相比，新陈代谢依赖的毒性由 环境污染物。因为人类和人类之间的守恒 小鼠和人类的CYP1A1和AHR基因的多态是已知的 在这些完整的小鼠身上进行的研究应该有助于阐明这种机制 周围的遗传差异导致的毒性易感性 CYP1A1的底物，以及AHR的配体。

DESCRIPTION (from Applicant's Abstract): The long-term goal of this project is to understand the role that SYP1A1 (cytochrome P1-450) plays in toxicity caused by environmental pollutants. Cyp1a1 is a member of the dioxin-inducible [ah] battery, the genes of which are up-regulated by the ah receptor (AHR). The CYP1A1 enzyme oxgenates halogenated and polycyclic aromatic hydrocarbons, e.g. polychlorniated biphenyls (PCBs) and benzo[a]pyrene(BaP). AHR ligands include dioxin (which is metabolised extremely slowly) and PCBs and BaP (which are metabolised more rapidly). The [Ah] battery plays a major role in toxicity of the skin, bone marrow, liver, eye, ovary, and immune system--as well as carcinogenesis. In the mouse the dosage and route of BaP administration are important determinants in target organ toxicity. Genetic differences in BaP toxicity depends upon the high-affinity C57BL/6-type (Ahr(b) allele) or the low-affinity DBA/2-type(Ahr(d) allele) of Ah receptor. Expression of mouse CYP1A1 mRNA is constitutively low absent, but is highly inducible in virtually every tissue and cell type in the body--following exposure to polycyclic aromatic chemicals. Toxicity can occur by either metabolism-dependent or receptor-dependent (metabolism- independent) mechanism. This laboratory has recently collaborated in making the Ahr(-/-) knockout mouse line. To investigate the mechanisms of CYP1A1 metabolism-mediated, vs. AHR-mediated toxicity caused by environmental chemicals, we therefore propose to: [1] develop a conventional, as well as an inducible, Cypla(-/-) knockout transgenic mouse line; [2] develop a (global, rather than tissue-specific) Cyp1a1(u/u) (ultra-expression) transgenic mouse line, and then generate, by breeding, the combined mouse lines Cyp1a1(-/-)Ahr(-/-), Cyp1a1 (-/-)Ahrd/d), Cyp1a1(-/-)Ahr(b/b), Cyp1a1(u/u)Ahr(-/-), Cyp1a1(u/u)Ahr(d/d), and Cyp1a1(u/u)Ahr(b/b). [3] study bone marrow toxicity and skin inflammation, following treatment of these mouse lines with oral BaP and with topical 7,12-dimethylbenzo[a]anthracene(DMBA), respectively, to determine which forms of environmental toxicity are dependent on CYP1A1 metabolism, and which forms of toxicity are dependent on the Ah receptor. These studies will greatly enhance our understanding of CYP1A1 metabolism-dependent, compared with AHR-dependent, toxicity caused by environmental pollutants. Because of conservation between human and mouse, and human polymorphisms in the CYP1A1 and AHR genes are known to exist, studies in these intact mice should help elucidate the mechanisms surrounding genetic differences in susceptibility to toxicity caused by substrates of CYP1A1, as well as ligands of the AHR.