Mechanisms of Intercellular Communication in Drosophila

Bejsovec实验室的长期目标是了解信号分子如何在发育中的胚胎中分布，以及这种分布如何指定组织内的位置信息。该实验室专注于分泌生长因子的Wnt家族，该家族在所有动物胚胎发育过程中指定细胞命运方面发挥着核心作用。 这些分子经历脂质修饰，但能够在远离源细胞的细胞群中促进长距离信号传导事件。 在胚胎中，这些事件包括神经系统、四肢和内脏器官的模式化;在成年人中，Wnt信号促进干细胞群中的细胞增殖，并且该途径的不适当激活与人类癌症，特别是结直肠癌有关。 果蝇强大的遗传学使其成为探索Wnt分布和信号活性的分子和细胞机制的极好模型系统。在果蝇胚胎中，Wnt同源物Wingless（Wg）产生于表皮每个部分的单行细胞中，但其活性需要在该部分的所有细胞中进行适当的图案化。Bejsovec实验室以前的工作表明，Wg可以突变以破坏其运动，而不会破坏其内在的信号活性。这表明Wg分布的细胞机制独立于其信号转导途径。为了确定负责Wg蛋白分布的细胞机制，已分离出抑制运动缺陷突变体表型的第二位点突变：这些突变显示的表型表明它们影响Wg转运过程。 本申请的目的1提出表征通过其抑制表型鉴定的基因，目的2提出用于鉴定转运所需的其他组分的功能增益技术。 这些实验方法将揭示参与处理和传播Wg/Wnt信号的机制的细节。智力优势：在信号转导领域，大多数工作集中在了解受体激活和随后的细胞内事件触发的配体-受体相互作用。关于配体如何到达远处的靶细胞以触发反应，我们知道的要少得多，但这是胚胎发育中的一个关键问题，许多信号分子对图案化有长期影响。这个项目，如果得到资助，将定义配体运输所需的细胞机制。 识别和表征负责配体运动的蛋白质是理解这一重要现象的关键第一步。更广泛的影响：配体分布可能在肿瘤发生和转移中发挥作用，除了其在调节胚胎模式形成中的基本作用。在果蝇中的这项工作将确定配体转运所需的细胞成分，这些成分可能具有在脊椎动物中发挥类似作用的同源物。这些可能揭示肿瘤发生过程中突变的新靶点，了解它们的活性将为Wnt相关癌症的治疗干预提供线索。基因筛选的建议是理想的介绍高中生和大学生的基础研究。该实验室致力于为学生，特别是妇女和代表性不足的少数民族，提供在研究实验室的实践经验。过去的学生共同撰写论文，证明他们在研究工作的深度参与。

Project Summary The long term goals of the Bejsovec laboratory are to understand how signaling molecules are distributed within developing embryos and how that distribution specifies positional information within a tissue. The lab focuses on the Wnt family of secreted growth factors, which play a central role in specifying cell fates during the development of all animal embryos. These molecules undergo lipid-modification but are capable of promoting long-range signaling events in populations of cells distant from the source cells. In embryos, these events include patterning of the nervous system, limbs and internal organs; in adults, Wnt signaling promotes cell proliferation in stem cell populations and inappropriate activation of the pathway is associated with human cancers, particularly colorectal cancer. The powerful genetics of Drosophila make it an excellent model system for exploring the molecular and cellular mechanisms of Wnt distribution and signaling activity. In Drosophila embryos, the Wnt homolog, Wingless (Wg), is produced in a single row of cells in each segment of the epidermis but its activity is required in all cells of the segment for proper patterning. Previous work in the Bejsovec lab has shown that Wg can be mutated to disrupt its movement without destroying its intrinsic signaling activity. This suggests a cellular mechanism for Wg distribution that is independent of its signal transduction pathway. To identify the cellular machinery responsible for Wg protein distribution, second site mutations that suppress the movement-defective mutant phenotype have been isolated: these mutations show phenotypes suggesting that they influence the Wg transport process. Aim 1 of this application proposes to characterize the genes identified by their suppressor phenotypes and Aim 2 proposes gain of function techniques for identifying other components required for transport. These experimental approaches will reveal details of the machinery involved in processing and propagating the Wg/Wnt signal. Intellectual Merit: In the field of signal transduction, most work has focussed on understanding receptor activation and the subsequent intracellular events triggered by ligand-receptor interaction. Much less is known about how ligands arrive at distant target cells to trigger response, yet this is a critical problem in embryonic development where many signaling molecules have long-range effects on patterning. This project, if funded, will define the cellular machinery required for ligand transport. Identifying and characterizing the proteins responsible for ligand movement is a crucial first step in understanding this important phenomenon.Broader Impacts: Ligand distribution may play a part in tumorigenesis and metastasis, in addition to its fundamental role in regulating embryonic pattern formation. This work in Drosophila will identify cellular components required for ligand transport which may have homologs that play a similar role in vertebrates. These may reveal new targets of mutation during oncogenesis, and understanding their activity will provide clues for therapeutic intervention in Wnt-associated cancers. The genetic screens proposed are ideal for introducing high school students and undergraduates to basic research. This laboratory is committed to providing students, particularly women and under-represented minorities, with hands-on experience in a research laboratory. Past students have co-authored papers, demonstrating their deep involvement in the research effort.