LIVER SPECIFIC, INDUCIBLE TRANSGENE AND HEPATOTOXICITY

描述：一些外来毒素会改变一组基因的表达 通过首先诱导基因的表达在肝脏中表达特定的基因 编码转录因子ATF3，它是bZIP(基本的 区域亮氨酸拉链)蛋白和ATF/CREB家族成员 转录因子。ATF3结合的共同序列已经被 在许多肝脏特异性基因启动子中发现，特别是那些 认为可以调节鸟氨酸转氨甲基酶、醛缩酶、转铁蛋白、 α-抗胰蛋白酶、载脂蛋白B、一些急性期基因，例如， 谷胱甘肽-S-转移酶和特异性细胞色素P450基因。ATF3是 由生理应激源引起的，包括：a)暴露于诸如 四氯化碳、对乙酰氨基酚和酒精，b)机械损伤，c) 限制流向心脏的血液，以及d)脑部癫痫。它的 表达与细胞损伤和细胞死亡相关。因此，这 该项目的重点是ATF3在异种生物诱导的肝脏毒性中的作用 人类。首席调查者假设“微扰的 BZip池将导致肝功能的解除调节。 这项提议的目标是通过在 使用组织特异性二元反式激活剂/反式应答器的肝脏 转基因小鼠模型。具体目标是：1)创造个性 反式激活剂和反式反应转基因小鼠，2)跨线 创造生物小鼠，以及3)测试“放松管制”的后果 ATF3在成年动物和胚胎发育过程中的过度表达。 一种肝脏特异的、经甲状腺激素驱动的“反向四环素”诱导 系统将被用来调节ATF3转基因的肝脏表达 (用血凝素[HA]序列标记，该序列可通过 使用抗HA抗体的免疫学方法)。为了实现这一点， 转甲状腺激素四环素转基因小鼠的低拷贝表达 抑制子结构(“反式激活子”)将被培育成低拷贝的线条。 表达ATF3-HA融合结构的转基因小鼠(“转应者”) 以创造生物原生或双转基因品系。后代将被用来 研究ATF3系统在成年期和老年期间的扰动 异种药物引起的胎儿(肝脏)发育期。 将在成年转基因小鼠中检测ATF转基因表达。这个 需要解决的问题是，ATF3表达增加是否会增加 对外来物质的敏感性。异源生物的次优浓度 将对药物进行测试，以确定ATF3在生物小鼠中的表达是否增加 增强这些制剂的效果。反义ATF转基因的作用 在胚胎发育期间也将检查肝功能的表达情况。 发展。

DESCRIPTION: A number of xenobiotic toxins alter expression of a subset of specific genes in the liver by first inducing expression of the gene encoding the transcription factor, ATF3, which is a bZIP (basic region-leucine zipper) protein and a member of the ATF/CREB family of transcription factors. Consensus sequences for ATF3 binding have been identified in a number of liver-specific gene promoters, specifically those thought to regulate ornithine transcarbamylase, aldolase, transferrin, alpha-antitrypsin, apolipoprotein B, some acute phase genes, e.g., glutathione-S-transferase, and specific cytochrome P450 genes. ATF3 is induced by physiological stressors including: a) exposure to agents such as carbon tetrachloride, acetaminophen and alcohol, b) mechanical injury, c) restriction of blood flow to the heart, and d) brain seizure. Its expression correlates with cellular injury and cell death. Therefore, this project focuses on the role of ATF3 in xenobiotic-induced liver toxicity in humans. The principal investigator hypothesizes that "perturbation of the bZip pool will lead to the de-regulation of liver functions." Thus, the goal of this proposal is to test the hypothesis by over-expressing ATF3 in the liver using a tissue-specific binary transactivator/transresponder transgenic mouse model. The specific aims are to: 1) create individual transactivator and transresponder transgenic mice, 2) to cross the lines to create the biogenic mice, and 3) to test the consequences of "deregulated over-expression" of ATF3 in adult animals and during embryonic development. A liver-specific, transthyretin-driven "reverse tetracycline" induction system will be used to regulate hepatic expression of an ATF3 transgene ("tagged" with a hemagglutinin [HA] sequence that is detectable by immunological methods using antiHA antibodies). To achieve this, lines of low-copy transgenic mice expressing transthyretin-directed tetracycline repressor constructs ("transactivators") will be bred to lines of low-copy transgenic mice expressing the ATF3-HA fusion construct ("transresponders") to create biogenic or double-transgenic lines. Offspring will be used to study perturbation of the ATF3 system during adulthood as well as during the period of fetal (hepatic) development by xenobiotic agents. ATF-transgene expression will be examined in adult transgenic mice. The question to be addressed is whether increased ATF3 expression increases the sensitivity to xenobiotic agents. Sub-optimal concentrations of xenobiotic agents will be tested to see if heightened ATF3 expression in biogenic mice potentiates effects of these agents. The effects of aberrant ATF-transgene expression on liver function will also be examined during embryonic development.