CYP1A1 GENE AND ENVIRONMENTAL TOXICITY

描述（来自申请人的摘要）： 长期目标是 该项目的目的是了解SYP1A1（细胞色素P1 - 450）所起的作用 由环境污染物引起的毒性。 Cyp 1a 1是 二恶英诱导电池，其基因被上调， Ah受体（AHR）。 CYP1A1酶使卤化氧合， 多环芳烃，例如多氯联苯 和苯并[a]芘（BaP）。 AHR配体包括二恶英（dioxin）（其是 多氯联苯和苯并（a）芘（代谢非常缓慢） 更快）。 [Ah]电池在电池的毒性中起主要作用。 皮肤、骨髓、肝脏、眼睛、卵巢和免疫系统， 致癌作用 在小鼠中，BaP给药的剂量和途径 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的C57BL/6型 （Ahr（B）等位基因）或低亲和力DBA/2型（Ahr（d）等位基因 受体的 小鼠CYP1A1 mRNA的表达组成性低， 但在几乎所有的组织和细胞类型中都是高度可诱导的， 身体-暴露于多环芳烃化学品后。 毒性可以 发生代谢依赖或受体依赖（代谢- 独立）机制。 该实验室最近与 制备Ahr（-/-）敲除小鼠系。 为了研究 CYP1A1代谢介导的毒性与AHR介导的毒性 环境化学品，因此我们建议： [1]开发一种常规的，以及诱导型，Cypla（-/-） 基因敲除转基因小鼠系; [2]开发（全局，而非组织特异性）Cyp1a1（u/u） （超表达）转基因小鼠系，然后通过 育种，组合小鼠品系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， 用口服BaP和局部用 7，12-二甲基苯并[a]蒽（DMBA），分别测定 哪些形式的环境毒性依赖于CYP1A1 代谢，以及哪种形式的毒性取决于Ah 受体的 这些研究将大大提高我们对CYP1A1的认识 代谢依赖性，与AHR依赖性相比， 环境污染物 由于人类和 已知CYP1A1和AHR基因中的小鼠和人类多态性 存在，在这些完整的小鼠中的研究应该有助于阐明 周围的遗传差异，对毒性的敏感性， 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.