Regulation of Drosophila Epithelial Polarity

描述(申请人提供)：组织的形态发生需要协调的细胞行为，通常发生在平面极化(PCP)的方式。极化形态发生的缺陷是各种人类病理的基础，包括与神经管开放相关的出生缺陷。虽然产生PCP模式的信号通路越来越被人们所了解，但我们对这种模式驱动PCP形态发生的机制知之甚少。这个项目的长期目标是了解这些机制，以揭示细胞的极化及其形态发生行为是如何形成发育中的组织的。果蝇卵的伸长是一个简单但很少被研究的过程，它需要卵巢滤泡细胞上皮中PCP的形态发生。这个过程与脊椎动物重要的形态发生运动有几个共同的细胞特征，包括PCP细胞骨架，细胞外基质的参与，以及极化细胞突起的延伸。令人惊讶的是，尽管PCP组织了细胞骨架、基质和突起，但这些特征和卵子伸长本身都不需要典型的PCP途径的核心基因。通过正向遗传筛查，我们发现了与PCP及其发育结果相关的三个新的卵子伸长调节因子。我们假设，这些都定义了一条细胞内信号通路，指导发育中的卵子PCP的伸长。为了验证这一假设，并揭示管理和执行这一PCP形态发生事件的层次结构，我们将使用以下策略。我们将使用固定和活样本的高清晰度形态计量学分析来定义细胞突起的个体发育和动态行为。我们将使用遗传、分子和细胞生物学的方法来确定新的调节因子在组织毛囊细胞的突起、细胞骨架、细胞外基质和其他PCP特征中的作用，并将它们置于调控途径中。最后，我们将进行一次大规模的遗传筛选，以确定和表征与鸡蛋伸长有关的其他新因素。总体而言，我们的研究将阐明目前知之甚少的PCP组织驱动组织形态发生的一般机制。他们将通过阐明PCP形态发生的机制来推动这一领域的发展，在一种新的背景下，遗传学、细胞生物学和成像都将发挥作用。最后，他们将为未来理解形态发生如何整合细胞内和细胞外力以赋予器官最终形式奠定基础。 与公共卫生相关：许多人体组织的正确形成，包括神经管的关闭，需要执行在上皮组织平面内极化的细胞运动。在这个平面上极化细胞表面的途径已经被发现，然而我们还不知道这个被很好描述的平面极性途径实际上指导形成器官的细胞行为的机制。这项提议将探索平面细胞极性信号下游的细胞和分子机制，通过利用果蝇的遗传可操作性来理解一个简单的平面极化过程，该过程赋予苍蝇卵椭圆形而不是圆形。

DESCRIPTION (provided by applicant): Morphogenesis of tissues requires coordinated cell behaviors that often occur in a planar polarized (PCP) fashion. Defects in polarized morphogenesis underlie various human pathologies including birth defects associated with open neural tubes. While the signaling pathway that generates PCP pattern is increasingly well-understood, we have little information about the mechanisms through which this patterning drives PCP morphogenesis. The long- term goal of this project is to understand these mechanisms in order to reveal how polarization of cells and their morphogenetic behaviors gives final form to a developing tissue. Elongation of the Drosophila egg is a simple but little-studied process that requires PCP morphogenesis in the ovarian follicle cell epithelium. This process shares several cellular features with important vertebrate morphogenetic movements, including a PCP cytoskeleton, the involvement of the extracellular matrix, and the extension of polarized cellular protrusions. Surprisingly, despite the PCP organization of cytoskeleton, matrix, and protrusions, neither these features nor egg elongation itself requires the core genes of the canonical PCP pathway. Through a forward genetic screen, we have discovered three new regulators of egg elongation that are linked to PCP and its developmental outcomes. We hypothesize that these define an intracellular signaling pathway that directs PCP elongation of the developing egg. To test this hypothesis, and to uncover the hierarchy governing and executing this PCP morphogenetic event, we will use the following strategies. We will employ high-definition morphometric analysis of fixed and live samples to define the ontogeny and dynamic behavior of cellular protrusions. We will use genetic, molecular and cell biological approaches to identify the role of the novel regulators in organizing protrusions, cytoskeleton, extracellular matrix, and other PCP features of the follicle cells and to place them into a regulatory pathway. Finally, we will carry out a large genetic screen to identify and characterize additional novel factors involved in egg elongation. Overall, our studies will shed light on the poorly-understood general mechanisms by which PCP organization drives tissue morphogenesis. They will move the field forward by elucidating a mechanism of PCP morphogenesis in a novel context where genetics, cell biology, and imaging are all brought to bear. Finally, they will set the stage for a future understanding of how morphogenesis integrates both internal cellular and extracellular forces to give organs their final forms. PUBLIC HEALTH RELEVANCE: Proper formation of many human tissues, including closure of the neural tube, requires execution of cell movements that are polarized within the plane of an epithelial tissue. A pathway that polarizes cell surfaces in this plane has been uncovered, yet we do not understand the mechanisms by which this well- characterized planar polarity pathway actually direct the cellular behaviors that shape an organ. This proposal will explore the cellular and molecular mechanisms that lie downstream of planar cell polarity signaling to regulate morphogenesis, by exploiting the genetic manipulability of the fruit fly to understand a simple planar polarized process that confers oval rather than round shape to the fly egg.