Palanker Laura, Necakov Aleksandar S, Sampson Heidi M, Ni Ruoyu, Hu Chun, Thummel Carl S, Krause Henry M
Department of Human Genetics, Howard Hughes Medical Institute, University of Utah School of Medicine, Salt Lake City, UT 84112-5331, USA.
Development. 2006 Sep;133(18):3549-62. doi: 10.1242/dev.02512. Epub 2006 Aug 16.
Nuclear receptors are a large family of transcription factors that play major roles in development, metamorphosis, metabolism and disease. To determine how, where and when nuclear receptors are regulated by small chemical ligands and/or protein partners, we have used a 'ligand sensor' system to visualize spatial activity patterns for each of the 18 Drosophila nuclear receptors in live developing animals. Transgenic lines were established that express the ligand binding domain of each nuclear receptor fused to the DNA-binding domain of yeast GAL4. When combined with a GAL4-responsive reporter gene, the fusion proteins show tissue- and stage-specific patterns of activation. We show that these responses accurately reflect the presence of endogenous and exogenously added hormone, and that they can be modulated by nuclear receptor partner proteins. The amnioserosa, yolk, midgut and fat body, which play major roles in lipid storage, metabolism and developmental timing, were identified as frequent sites of nuclear receptor activity. We also see dynamic changes in activation that are indicative of sweeping changes in ligand and/or co-factor production. The screening of a small compound library using this system identified the angular psoralen angelicin and the insect growth regulator fenoxycarb as activators of the Ultraspiracle (USP) ligand-binding domain. These results demonstrate the utility of this system for the functional dissection of nuclear receptor pathways and for the development of new receptor agonists and antagonists that can be used to modulate metabolism and disease and to develop more effective means of insect control.
核受体是一类庞大的转录因子家族，在发育、变态、代谢和疾病中发挥着重要作用。为了确定核受体如何、在何处以及何时受到小分子化学配体和/或蛋白质伴侣的调控，我们使用了一种“配体传感器”系统，以可视化发育中的活体动物体内18种果蝇核受体各自的空间活性模式。构建了转基因品系，这些品系表达与酵母GAL4的DNA结合结构域融合的每种核受体的配体结合结构域。当与GAL4响应报告基因结合时，融合蛋白显示出组织和阶段特异性的激活模式。我们表明，这些反应准确反映了内源性和外源性添加激素的存在，并且它们可以被核受体伴侣蛋白调节。羊膜、卵黄、中肠和脂肪体在脂质储存、代谢和发育时间调控中起主要作用，被确定为核受体活性的常见位点。我们还观察到激活的动态变化，这表明配体和/或辅因子产生发生了全面变化。使用该系统对一个小分子化合物库进行筛选，确定角补骨脂素当归素和昆虫生长调节剂苯氧威为超气门蛋白（USP）配体结合结构域的激活剂。这些结果证明了该系统在核受体途径功能剖析以及开发可用于调节代谢和疾病以及开发更有效昆虫控制手段的新型受体激动剂和拮抗剂方面的实用性。
