Novel Regulation of Pattern Formation in Drosophila

果蝇在实验室中很容易操作，可以用来发现控制动物胚胎生长和形成的基因。给果蝇喂食一种导致DNA突变的化学物质，繁殖后代，然后检查果蝇的发育变化。一个重要基因的突变会导致身体模式的巨大变化。用这种方法鉴定的许多苍蝇基因都有人类的对应基因，它们在人类发育过程中发挥着非常相似的功能。Bejsovec实验室使用这种策略来研究果蝇和人类共享的遗传途径的内部工作原理。这条通路由Wg/Wnt生长因子触发，告诉细胞它们在体内的位置和形成什么样的特殊结构；成人组织中Wnt通路的不适当再激活与人类癌症有关。Bejsovec实验室发现，已知的三个共同控制细胞分裂的基因在控制Wnt通路方面具有第二个意想不到的功能。这个项目将确定这些基因是如何控制这一途径的，以及它们的作用是如何破坏果蝇的身体计划的。该项目的更广泛影响包括加深对所有动物物种发育机制的理解，并为本科生和高中生在Bejsovec实验室和本科生在现有的实验课程中提供实践研究经验。尽管Wg/Wnt通路在发育和组织稳态中起着核心作用，但从Wg/Wnt在细胞表面结合到下游靶基因激活的一系列事件仍未完全了解。风滚草（Tum）、帕瓦罗蒂（Pav）和卵石（Pbl）抑制培养的人细胞和苍蝇胚胎中Wg/Wnt通路的活性。这些基因可能代表了一个关键的缺失环节，可能在早期筛选Wg/Wnt通路组分时遗漏了，因为这三个基因在细胞分裂中都具有基本功能。在细胞质分裂中，Tum和Pav将pbr - rhogef定位在赤道，激活组织肌动蛋白收缩环的G蛋白Rho。这里提出的工作将确定Tum、Pav和Pbl是否（以及如何）与已知的Wg/Wnt组分接触，并将测试是否涉及GTPase激活。此外，降低成体前体细胞中的Tum或Pbl功能会产生一种新的同质转化，这可能是由于细胞信号传导和细胞分裂同时中断造成的。在果蝇中可用的遗传和分子工具将用于确定信号和/或细胞分裂的错误调节如何改变片段身份。所得到的数据将为Wg/Wnt通路控制和组织模式提供深入的见解，并可能揭示发育过程中细胞分裂和细胞命运规范之间的新联系。改造后的果蝇的独特外观将吸引本科生和高中生，让他们参与科学事业，并帮助招募包括女性、社会经济弱势群体和代表性不足的少数民族学生在内的多元化群体进入劳动力市场。

The fruitfly, Drosophila, is easy to manipulate in the laboratory and can be used to discover genes that control the growth and shaping of animal embryos. Flies are fed a chemical that causes mutations in the DNA, the progeny are bred and then examined for altered development of the fly. A mutation that breaks an essential gene will cause dramatic changes in the body pattern. Many of the fly genes identified this way have human counterparts, which perform very similar functions during human development. The Bejsovec laboratory uses this strategy to study the inner workings of a genetic pathway that is shared between flies and humans. This pathway, triggered by the Wg/Wnt growth factor, tells cells where they are in the body and what special structure to become; inappropriate re-activation of the Wnt pathway in adult tissues is associated with human cancers. The Bejsovec lab has found that three genes already known to work together to control cell division, have a second unexpected function in controlling the Wnt pathway. This project will determine how these genes exert control over the pathway, and how their action disrupts the fly body plan. Broader impacts of the project include deeper understanding of developmental mechanisms in all animal species, and a hands-on research experience for undergraduate and high school students in the Bejsovec laboratory and for undergraduates in an existing laboratory course. Although the Wg/Wnt pathway plays a central role in development and tissue homeostasis, the sequence of events, from Wg/Wnt binding at the cell surface to the downstream activation of target genes, is still not completely understood. Tumbleweed (Tum), Pavarotti (Pav) and Pebble (Pbl) repress Wg/Wnt pathway activity in cultured human cells and in fly embryos. These genes may represent a crucial missing link, perhaps missed in earlier screens for Wg/Wnt pathway components because all three genes have essential functions in cell division. In cytokinesis, Tum and Pav position Pbl-RhoGEF at the equator to activate the G protein, Rho, which organizes the actin contractile ring. Work proposed here will determine whether (and how) Tum, Pav, and Pbl make contact with known Wg/Wnt components, and will test whether GTPase activation is involved. In addition, reducing Tum or Pbl function in adult precursor cells creates a novel homeotic transformation which may result from the simultaneous disruption of cell signaling and cell division. Genetic and molecular tools available in Drosophila will be used to determine how misregulation of signaling and/or cytokinesis might alter segmental identity. The resulting data will provide insight into Wg/Wnt pathway control and tissue patterning, and may reveal new connections between cell division and cell fate specification during development. The unique appearance of the transformed flies will appeal to undergraduate and high school students, engaging them in the scientific enterprise and helping to recruit a diverse group, including women, socioeconomically disadvantaged and underrepresented minority students, into the workforce.