CAREER: Mechanisms of Intercellular Communication in Drosophila

分泌的信号分子Wingless （Wg）及其脊椎动物同源物Wnt家族在产生胚胎位置信息和调节细胞增殖中发挥关键作用。该实验室最近的研究表明，无翼信号分子的活跃细胞运输对于果蝇胚胎表皮细胞命运的指定至关重要。Wg的一种突变形式显示出远离产生它的细胞的受限运动，这与通常由Wg信号所指定的细胞命运多样性的减少有关。因此，Wg在表皮上皮细胞中的横向运动对细胞命运的确定具有重要的功能。这种平面形式的胞吞作用与已知的胞吞作用非常不同，胞吞作用发生在极化上皮的顶-基或基底-顶方向。了解这种新的细胞间转运机制对研究Wg/Wnt生物学至关重要。本提案的具体目标是：(1)确定运输所需的Wg蛋白和Wnt蛋白的结构特征；(2)通过干扰体内和体外的内吞过程，探索影响Wg运动的细胞机制；(3)从遗传和分子上鉴定了两个可能参与发育过程中Wg蛋白转运的新基因。这项研究工作激发了示范材料的发展，以激发大学预科、本科和研究生教育环境中对生物学的兴趣。果蝇突变株通常用于证明遗传原理，但它们也可以提供基本发育和细胞生物学现象的戏剧性插图，如模式形成和内吞作用。拟议的教育计划的一个主要目标是在课堂上发展和推广这些目的的使用。具体目标包括改进一些果蝇品种，使教育者更容易操作，编写一套教学材料，以呈现和解释日益复杂的细胞现象，并在西北大学的高级本科细胞生物学课程中试用这些示范材料。

The secreted signaling molecule, Wingless (Wg) and its vertebrate homologues, the Wnt family, play critical roles in generating embryonic positional information and in regulating cell proliferation. Recent work in this laboratory has revealed that active cellular transport of the Wingless signaling molecule is essential for specification of cell fates in the embryonic epidermis of Drosophila. A mutant form of Wg that shows restricted movement away from the cells that produce it is associated with a reduction in the diversity of cell fates normally specified by Wg signaling. Thus, lateral movement of Wg through cells in the epidermal epithelium is functionally important for cell fate specification. This planar form of transcytosis is very different from known instances of transcytosis, which occur in an apical-basal or basal-apical direction across a polarized epithelium. Understanding the mechanism of this novel intercellular transport is essential to the study of Wg/Wnt biology. The specific goals of this proposal seek to: (1) identify structural features of the Wg protein, and of Wnt proteins in general, that are required for transport; (2) explore the cellular machinery responsible for effecting the movement of Wg by perturbing the endocytic process both in vivo and in vitro; and (3) characterize genetically and molecularly two new genes that appear to be involved in Wg protein transport during development. This research work has inspired the development of demonstration materials for stimulating interest in biology in pre-college, undergraduate and graduate educational settings. Drosophila mutant strains are commonly used for demonstrating genetic principles, but they can also provide dramatic illustrations of basic developmental and cell biological phenomena such as pattern formation and endocytosis. A major goal of the proposed education plan is to develop and popularize their use for these purposes in the classroom. Specific goals include improving several fly strains for easier manipulation by educators, writing a set of instructional materials to present and explain the cellular phenomena at increasing levels of sophistication, and piloting the use of these demonstration materials in an advanced undergraduate cell biology course at Northwestern University.