Regulation of Drosophila Epithelial Polarity

描述（由申请人提供）：组织的形态发生需要协调的细胞行为，通常以平面极化（PCP）方式发生。极化形态发生的缺陷是各种人类病理的基础，包括与开放神经管相关的出生缺陷。虽然产生PCP模式的信号通路越来越清楚，但我们对这种模式驱动PCP形态发生的机制知之甚少。该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如何最终形成发育中的组织。果蝇卵的伸长是一个简单但很少研究的过程，它需要卵巢卵泡细胞上皮的PCP形态发生。这一过程与重要的脊椎动物形态发生运动有几个共同的细胞特征，包括PCP细胞骨架、细胞外基质的参与和极化细胞突起的延伸。令人惊讶的是，尽管细胞骨架、基质和突起具有PCP组织，但这些特征和卵子伸长本身都不需要典型PCP途径的核心基因。通过前向遗传筛选，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。我们假设这些定义了一种细胞内信号通路，指导发育中的卵的PCP伸长。为了验证这一假设，并揭示控制和执行PCP形态发生事件的层次结构，我们将使用以下策略。我们将采用固定和活样本的高清形态计量学分析来定义细胞突起的个体发生和动态行为。我们将使用遗传、分子和细胞生物学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，并将它们置于调节途径中。最后，我们将进行一个大的遗传筛选，以确定和表征额外的新因素参与卵子延长。总的来说，我们的研究将阐明PCP组织驱动组织形态发生的一般机制。他们将在遗传学、细胞生物学和影像学的新背景下阐明PCP形态发生的机制，从而推动该领域的发展。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量以赋予器官最终形态奠定基础。

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.