A Drosophila Model for Genetic Studies of Metabolism

描述（由申请人提供）：本申请涉及广泛的挑战领域（15）：转化科学和特定的挑战主题15-DK-102：开发NIDDK疾病的改良动物模型。代谢稳态在胚后生活的各个方面起着核心作用，使动物能够平衡日常生存所需的能量摄入。相反，代谢失调会导致肥胖和2型糖尿病，这是人类疾病的关键风险因素，包括心血管疾病和癌症。我们的研究目标是使用果蝇，果蝇，作为一个简单的模型系统，以定义控制代谢和维持能量稳态在所有高等生物，包括人类的中央调节途径。我们的实验方法利用果蝇作为模型系统的独特优势，在完整的动物中进行开放式遗传筛选。这一建议源于我们正在进行的果蝇核受体信号转导和这些因素在维持代谢稳态中的核心作用的研究。遗传学研究表明，需要核受体DHR 96来维持动物体内适当的三酰甘油（TAG）水平。DHR 96突变体是可行的，具有低水平的TAG，并且对饥饿敏感，与关键脂质代谢基因的失调相关。我们已经发现，DHR 96突变体的饥饿敏感性可以通过在增加TAG水平的基因中引入第二位点突变来拯救，例如脂肪甘油三酯脂肪酶基因或脂肪运动激素受体基因（其作用类似于胰高血糖素以驱动脂解）。这一观察结果为识别控制脂质代谢的新基因提供了一个框架。我们建议利用DHR 96突变体作为敏感的遗传背景进行开放式遗传筛选，目的是识别拯救其饥饿敏感性的突变。我们的初步数据表明，这种筛选应该揭示一系列涉及脂质代谢许多方面的基因，包括突变时导致肥胖的基因。最近开发的通过转座子诱变进行有效的单基因破坏的方法将促进筛选并允许快速的基因鉴定。这些研究为利用果蝇作为扩展我们对影响人类健康的关键脂质代谢途径的理解的手段提供了新的基础。遗传筛选代表了在果蝇中工作的最强大和最重要的优势之一，并提供了一种方法来扩大我们对特定生物学途径的理解，在新的和意想不到的方向。这种方法对我们理解人类健康产生了重大影响，通过描绘决定胚胎发育的基本途径和发现中央信号通路，如Notch，Wnt和hedgehog信号。我们建议利用果蝇的这种力量来发现影响脂质代谢的新基因。我们将把研究重点放在新发现的果蝇基因上，这些基因在小鼠和人类中具有密切的同源性，以促进我们的发现转化为脊椎动物系统。我们的长期目标是为小鼠基因敲除研究和人类疾病基因定位提供新的候选基因。通过这种方式，我们希望利用果蝇作为基因发现的工具，并将这些进展扩展到更好地了解人类代谢紊乱的原因。 公共卫生相关性：糖尿病和肥胖症等代谢性疾病的急剧增加对世界人口构成了重大健康风险。这项拟议的研究将使用果蝇作为一个简单的遗传模型系统来定义控制脂质代谢的基本机制，目的是为理解和治疗人类代谢紊乱提供新的方向。

DESCRIPTION (provided by applicant): This application addresses the broad Challenge Area (15): Translational Science and the specific Challenge Topic 15-DK-102: Develop improved animal models of NIDDK diseases. Metabolic homeostasis plays a central role in all aspects of postembryonic life, allowing animals to balance their dietary intake with the energy needs required for day-to-day survival. Conversely, misregulation of metabolism can lead to obesity and type 2 diabetes, which are critical risk factors for human disease, including cardiovascular disorders and cancer. The goal of our research is to use the fruit fly, Drosophila melanogaster, as a simple model system to define the central regulatory pathways that control metabolism and maintain energy homeostasis in all higher organisms, including humans. Our experimental approach exploits the unique strengths of Drosophila as a model system by conducting an open-ended genetic screen in the intact animal. This proposal arises from our ongoing studies of nuclear receptor signaling in Drosophila and the central role of these factors in maintaining metabolic homeostasis. Genetic studies have demonstrated that the nuclear receptor DHR96 is required to maintain appropriate triacylglycerol (TAG) levels in the animal. DHR96 mutants are viable, have low levels of TAG, and are sensitive to starvation, correlating with the misregulation of key lipid metabolic genes. We have discovered that the starvation sensitivity of DHR96 mutants can be rescued by introducing second-site mutations in genes that increase TAG levels, such as the adipose triglyceride lipase gene or the adipokinetic hormone receptor gene (which acts like glucagon to drive lipolysis). This observation provides a framework for identifying new genes that control lipid metabolism. We propose to exploit the DHR96 mutant as a sensitized genetic background for conducting open-ended genetic screens with the aim of identifying mutations that rescue its starvation sensitivity. Our preliminary data indicate that this screen should uncover a range of genes involved in many aspects of lipid metabolism, including genes which, when mutated, lead to obesity. Recently developed methods for efficient single-gene disruption by transposon mutagenesis will facilitate the screen and allow rapid gene identification. These studies provide a new basis for using Drosophila as means of extending our understanding of key lipid metabolic pathways that impact human health. Genetic screens represent one of the most powerful and important advantages of working in Drosophila, and offer a way to expand our understanding of specific biological pathways in new and unexpected directions. This approach has had a major impact on our understanding of human health through the delineation of the fundamental pathways that dictate embryonic development and the discovery of central signaling pathways, such as Notch, Wnt, and hedgehog signaling. We propose to exploit this strength of the fly toward the discovery of novel genes that impact lipid metabolism. We will focus our studies on newly identified Drosophila genes that have close homologs in mice and humans to facilitate the translation of our discoveries into vertebrate systems. Our long-term goal is to provide new candidates for mouse gene knockout studies and human disease gene mapping. In this way we hope to use the fly as a tool for gene discovery and extend these advances toward a better understanding of the causes of human metabolic disorders. PUBLIC HEALTH RELEVANCE: The dramatic rise in metabolic disorders, such as diabetes and obesity, poses a major health risk to the world population. This proposed research will use the fruit fly, Drosophila, as a simple genetic model system to define the fundamental mechanisms that control lipid metabolism, with the goal of providing new directions for understanding and treating human metabolic disorders.