Novel Regulation of Pattern Formation in Drosophila

果蝇很容易在实验室中操纵，可以用来发现控制动物胚胎生长和成形的基因。苍蝇被喂食一种能引起DNA突变的化学物质，繁殖后代，然后检查苍蝇发育的改变。破坏一个基本基因的突变将导致身体模式的巨大变化。以这种方式鉴定的许多果蝇基因都有人类对应物，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苍蝇和人类之间共享的遗传途径的内部运作。这种由Wg/Wnt生长因子触发的途径告诉细胞它们在体内的位置以及要变成什么样的特殊结构;成年组织中Wnt途径的不适当重新激活与人类癌症有关。Bejsovec实验室发现，已知的三个基因共同控制细胞分裂，在控制Wnt通路方面具有第二个意想不到的功能。该项目将确定这些基因如何控制该途径，以及它们的行为如何破坏苍蝇的身体计划。该项目的更广泛的影响包括更深入地了解所有动物物种的发育机制，以及Bejsovec实验室的本科生和高中生以及现有实验室课程的本科生的实践研究经验。 虽然Wg/Wnt通路在发育和组织稳态中起着核心作用，但从细胞表面Wg/Wnt结合到下游靶基因激活的事件顺序仍然没有完全理解。Tumbleweed（Tum）、Pavarotti（Pav）和Pebble（Pbl）在培养的人类细胞和苍蝇胚胎中抑制Wg/Wnt途径活性。这些基因可能代表了一个关键的缺失环节，可能在早期的Wg/Wnt通路组分筛选中遗漏了，因为所有三个基因在细胞分裂中都具有重要功能。在胞质分裂中，Tum和Pav将Pbl-RhoGEF定位在赤道以激活G蛋白Rho，其组织肌动蛋白收缩环。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GTdR激活。此外，降低Tum或Pbl在成体前体细胞中的功能产生了一种新的同源异型转化，这可能是由于细胞信号传导和细胞分裂的同时破坏。果蝇中可用的遗传和分子工具将用于确定信号和/或胞质分裂的失调如何改变节段身份。由此产生的数据将提供深入了解Wg/Wnt通路控制和组织模式，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。改造苍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，并帮助招募多元化群体，包括妇女，社会经济弱势群体和代表性不足的少数民族学生，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.