Regulation of Armadillo dependent transcription in Drosophila

描述（由申请人提供）：Wnt信号传导在动物发育中起着重要作用，并且该途径的失调有助于各种人类疾病，包括各种癌症。所提出的实验旨在确定和表征果蝇同源无翅（Wg）信号通路的调节剂。虽然已经确定了该途径的许多核心成分，但Wg信号对基因表达模式的细胞特异性影响中涉及的因素仍然知之甚少。本提案中描述的实验重点在于阐明Wg信号如何通过转录辅激活因子Armadillo（Arm）的作用改变各种组织中的基因表达。为了确定Arm转录活性的调节因子，我们进行了小规模的遗传筛选，并确定了15个潜在的Arm活性调节因子。在筛选中鉴定的一个基因是mastermind（Mam），这是Notch信号通路中先前表征的共激活因子。该提议的前两个目的集中于测试Mam-RC（一种天然存在的短Mam同种型）是Arm活性的组织特异性调节剂的假设。具体目标1中概述的实验旨在确定Mam-RC调节Arm转录活性的分子机制。我们提出了细胞培养和生化实验，将测试Mam-RC与已知的臂转录复合物组分的物理和功能相互作用。具体目标2概述了旨在通过操纵发育中的果蝇的各种组织中的mam-RC表达水平来测试Mam-RC是体内Wg信号传导的组织特异性调节剂的假设的实验。除了Mam-RC，我们还鉴定了其他可能的Arm调节因子;具体目标3概述了旨在表征这些其他基因在体内和细胞培养中调节Arm的作用的实验。考虑到所有动物中通路组分的进化保守性，我们对这些新的Arm依赖性转录调节因子的研究结果可能为人类发育和疾病提供更深入的了解。

DESCRIPTION (provided by applicant): Wnt signaling plays an important role in animal development, and misregulation of the pathway contributes to various human diseases, including a variety of cancers. The proposed experiments are designed to identify and characterize regulators of the homologous Wingless (Wg) signaling pathway in Drosophila. Though many of the core components of the pathway have been identified, factors involved in the cell-specific effects of Wg signaling on gene expression patterns are still poorly understood. The experiments described in this proposal focus on elucidating how Wg signaling alters gene expression in various tissues through the action of the transcriptional coactivator, Armadillo (Arm). To identify regulators of Arm transcriptional activity, we performed a small-scale genetic screen and we identified 15 potential regulators of Arm activity. One gene identified in the screen was mastermind (Mam), a previously characterized coactivator in the Notch signaling pathway. The first two aims of this proposal are focused on testing the hypothesis that Mam-RC, a naturally occurring short isoform of Mam, is a tissue-specific regulator of Arm activity. Experiments outlined in Specific Aim 1 are designed to determine the molecular mechanism by which Mam-RC regulates Arm transcriptional activity. We propose cell culture and biochemical experiments that will test for both physical and functional interactions of Mam-RC with known components of the Arm transcription complex. Specific Aim 2 outlines experiments designed to test the hypothesis that Mam-RC is a tissue-specific regulator of Wg signaling in vivo, by manipulating the levels of mam-RC expression in various tissues in the developing fly. In addition to Mam-RC, we identified other possible regulators of Arm; Specific Aim 3 outlines experiments designed to characterize the role of these other genes in regulating Arm both in vivo and in cell culture. Given the evolutionary conservation of the pathway components in all animals, findings from our studies of these novel regulators of Arm-dependent transcription may provide greater insight into both human development and disease.