Transcriptional Control of Drosophila Detoxification Genes

描述（由申请人提供）：动物的生存经常受到热休克、氧化应激、缺氧、感染和来自环境的毒性挑战等形式的威胁。为了对抗这些威胁并维持体内平衡，动物进化出了复杂而特异的调控反应，包括关键防御基因的协调转录控制。这些调控网络中的许多已经在果蝇（Drosophila melanogaster）中被鉴定和表征，并显示出在进化过程中是保守的，为理解它们在人类中的控制提供了基础。这些反应也提供了关键的见解，在高等生物体的协调转录控制的分子机制。值得注意的是，动物最关键的防御反应之一--对有害化学物质解毒的能力--还没有用简单的遗传模型系统来表征。这些化合物，包括药物，农药，植物毒素和污染物，统称为外源性物质，构成癌症和呼吸道疾病的关键风险因素。异生素反应也仍然是制药业开发新药的一个主要障碍。我们已经证明，用一种广泛使用的异生物质，镇静剂苯巴比妥治疗果蝇，会导致基因表达的快速，广泛和协调的变化。许多苯巴比妥调控的基因编码酶，并提出了与解毒，保护，药物运输或排泄一致的功能。在DHR 96中的无效突变-脊椎动物异生素受体PXR和CAR的单一祖先果蝇直系同源物-影响这些基因中的一些的苯巴比妥调节，表明DHR 96可以通过促进昆虫中的异生素反应而像其脊椎动物对应物一样起作用。然而，大多数基因在没有DHR 96的情况下被药物适当地调节，这种作用也在小鼠PXR和CAR突变体中观察到，这提出了如何控制这种协调转录回路的问题。这个计划的目标是利用果蝇来定义异生物质转录反应的分子机制。我们将确定苯巴比妥调控的关键启动子序列， 转录和表征赋予这种控制的反式作用因子。我们还将确定DHR 96有助于异生物质转录反应的分子机制。 这项研究将为包括人类在内的高等生物如何科普有毒物质提供新的见解。 化合物在其环境中，并建立果蝇作为新的模型系统， 异生物反应调节

DESCRIPTION (provided by applicant): Animals live with constant threats to their survival in the form of heat shock, oxidative stress, hypoxia, infection, and toxic challenges from the environment. To combat these threats and maintain homeostasis, animals have evolved complex and specific regulatory responses that include the coordinated transcriptional control of key defensive genes. Many of these regulatory networks have been identified and characterized in the fruit fly Drosophila melanogaster, and shown to be conserved through evolution, providing a foundation for understanding their control in humans. These responses have also provided key insights into the molecular mechanisms of coordinate transcriptional control in higher organisms. Remarkably, one of the most critical defense responses in animals - the ability to detoxify harmful chemicals - has not yet been characterized using a simple genetic model system. These compounds, which include pharmaceuticals, pesticides, plant toxins, and pollutants, referred to collectively as xenobiotics, comprise a critical risk factor for cancer and respiratory diseases. Xenobiotic responses also remain a major impediment to the development of new drugs by the pharmaceutical industry. We have shown that treatment of Drosophila with a widely used xenobiotic, the sedative phenobarbital, results in a rapid, widespread, and coordinate change in gene expression. Many phenobarbital-regulated genes encode enzymes and have proposed functions consistent with detoxification, protection, drug transport, or excretion. A null mutation in DHR96 - the single ancestral fly ortholog of the vertebrate xenobiotic receptors PXR and CAR - affects the phenobarbital regulation of some of these genes, demonstrating that DHR96 can function like its vertebrate counterparts by contributing to xenobiotic responses in insects. Most genes, however, are properly regulated by drug in the absence of DHR96, an effect also seen in mouse PXR and CAR mutants, raising the question of how this coordinate transcriptional circuit is controlled. The goal of this proposal is to use Drosophila to define the molecular mechanisms of xenobiotic transcriptional responses. We will identify critical promoter sequences that are required for phenobarbitalregulated transcription and characterize the trans-acting factors that confer this control. We will also determine the molecular mechanisms by which DHR96 contributes to xenobiotic transcriptional responses. This research will provide new insights into how higher organisms, including humans, cope with toxic compounds in their environment and establish Drosophila as a new model system for characterizing xenobiotic response regulation.