Genetic Analysis of Epithelial Morphogenesis and Organ Shape

描述(申请人提供)：这项研究的长期目标是确定细胞群中细胞形状、极性和粘附性的动态调节如何在发育过程中塑造器官的形状。为此，我们正在果蝇身上使用遗传学和细胞生物学的方法来研究毛囊细胞上皮中一种新形式的平面极性是如何创造出一个被称为卵室的简单器官状单位的拉长形状。平面极性是一种发育机制，在这种机制中，单个细胞在组织平面内协调极化，为后续的形态发生事件提供方向信息。在苍蝇翅膀和眼睛中这一现象的开创性工作导致了Frizzled平面细胞极性通路的发现，现在已知这条通路塑造脊椎动物的体轴、内耳、肾脏和神经管。然而，Frizzled型信号盒在卵室延长过程中没有发挥作用，这表明对这一过程的研究很可能定义一个新的、或许类似保守的分子框架，调节平面极性和器官形状。我们的前两个具体目标是为了阐明这一非传统平面极性系统背后的细胞机制。Aim 1将使用遗传操作来验证这样的假设，即一种被称为极细胞的特殊细胞类型在邻近的毛囊细胞中诱导平面极性，而Aim 2将使用固定和实时成像技术来探索极化细胞突出活动的发展和功能，该活动代表了该组织中平面极性的最戏剧性的形态读数。为了补充这些细胞分析，我们进行了一项初步的遗传筛查，确定了调控该上皮平面图案和形态发生的关键分子途径。Aim 3将使用遗传和生化方法来研究这一信号级联的功能，Aim 4将采用一种高效的筛选策略，将寻找新的蛋形调节因子的工作扩展到果蝇基因组的其他区域。总之，这些研究将揭示控制卵泡细胞平面极性和卵室伸长的细胞和分子机制，并可能揭示指导广泛系统中器官形态发生的一般原理。

DESCRIPTION (provided by applicant): The long term goal of this research is to determine how the dynamic regulation of cell shape, polarity and adhesion across cell populations sculpts an organ's shape during development. To this end, we are using genetic and cell biological approaches in Drosophila to investigate how a novel form of planar polarity within the follicle cell epithelium creates the elongated shape of a simple organ-like unit known as an egg chamber. Planar polarity is a developmental mechanism in which individual cells are coordinately polarized within the plane of a tissue to provide directional information for subsequent morphogenetic events. Pioneering work on this phenomenon in the fly wing and eye led to the discovery of the Frizzled planar cell polarity pathway, which is now known to shape the vertebrate body axis, inner ear, kidneys and neural tube. The Frizzled signaling cassette plays no role in egg chamber elongation, however, indicating that the investigation of this process is likely to define a new and perhaps similarly conserved molecular framework regulating planar polarity and organ shape. Our first two specific aims are designed to elucidate the cellular mechanisms that underlie this unconventional planar polarity system. Aim 1 will use genetic manipulations to test the hypothesis that a specialized cell type known as the polar cells induces planar polarity in the neighboring follicle cells, while Aim 2 will use fixed and live imaging techniques to explore the development and function of a polarized cell protrusive activity that represents the most dramatic morphological readout of planar polarity in this tissue. To complement these cellular analyses, we performed a pilot genetic screen that identified a key molecular pathway regulating planar patterning and morphogenesis in this epithelium. Aim 3 will use genetic and biochemical approaches to investigate the function of this signaling cascade, and Aim 4 will employ a highly efficient screening strategy to extend the search for novel egg shape regulators to other regions of the Drosophila genome. Together these studies will reveal the cellular and molecular mechanisms controlling follicle cell planar polarity and egg chamber elongation, and are likely to reveal general principles guiding organ morphogenesis in wide range of systems.