Beyond cell shape: Actin exerts systems-level control during morphogenesis

超越细胞形状：肌动蛋白在形态发生过程中发挥系统级控制

• 批准号: 9099863
• 负责人: ANNA M SOKAC
• 金额: $ 30.51万
• 依托单位: BAYLOR COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-01 至 2020-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9099863
• 关键词: Actins; Actomyosin; Adult; Apical; Binding; Biochemical; Biological Assay; Cell Nucleus; Cell Shape; Cell membrane; Cell surface; Cells; Congenital Abnormality; Contracts; Coupled; Cytokinesis; Cytoskeleton; Data; Development; Disease; Drosophila genus; Embryo; Ensure; Environment; Epithelial; Epithelium; Event; F-Actin; Face; Failure; Genes; Genetic; Goals; Health; Human; Image; Individual; Kinetics; Knowledge; Learning; Life; Measurable; Mechanics; Membrane; Microfilaments; Modeling; Morphogenesis; Motor Activity; Myosin ATPase; Organism; Phase; Phenotype; Process; Proteins; Regulation; Role; Shapes; System; Testing; Time; Tissues; Vinculin; Work; alpha catenin; base; cellular microvillus; constriction; convergent extension; crosslink; depolymerization; design; embryo cell; environmental agent; falls; genome editing; human disease; member; multidisciplinary; novel; polymerization; prevent; research study

 DESCRIPTION (provided by applicant): Changes in cell shape drive morphogenesis and actin deficiencies cause failed cell shape change and birth defects. Yet our knowledge of actin's influence on morphogenesis is largely limited to lists of molecules and descriptions of gross phenotypes. While actin filaments (F-actin) are recognized as the major structural determinant of cell shape, basic questions remain unanswered: How is F-actin remodeled? How does it inter- face with cell membranes? How does it adapt to environmental or genetic variability? We need these answers to understand development and human disease. Our long-term goal is to fully understand actin's role in forming healthy tissues. We are focused on Drosophila cellularization, the process that builds the first epithelial sheet in the embryo. During cellularization, three cell surface remodeling events are going on in every new cell of the embryo: (i) microvilli disassemble; (ii) a membrane furrow ingresses; and (iii) an actomyosin ring contracts. We have shown that while these three remodeling events are spatially segregated over tens of microns, they are still kinetically coupled to each other and to measurable changes in the actomyosin ring. We have also identified specific F-actin regulators in the actomyosin ring that promote the robustness of cellularization against environmental and genetic perturbation. These results argue that actin does more than just give cells their shape. Our working model is that actin- based mechanisms also contribute to the coordination, kinetics, and robustness of morphogenesis. In this proposed work, we will test our model as follows: In Aim 1, we will test the hypothesis that plasma membrane tension, generated by furrow ingression, suppresses F-actin polymerization in microvilli, causing them to "unfold" or fall apart. In Aim 2, we will test he hypothesis that distinct kinetic phases of actomyosin ring contraction are governed by distinct mechanisms of F-actin regulation. In Aim 3, we will test the hypothesis that F-actin regulators, Srya and Spt, stabilize F-actin within the contractile ring to ensure robust cellularization in the face of environmental and genetic perturbation. We have assembled a multidisciplinary team of physicists, mathematicians and technologists; and we will employ a powerful combination of approaches, including quantitative live imaging, physical force assays, genetics, and genome editing to examine the events of cellularization in uncommon detail. Because the actin- based machinery that drives cellularization is widely conserved, our findings will be relevant to other organ- isms, including humans. We will establish how individual remodeling events are regulated in space and time, while also showing how the events are coordinated with each other to accomplish cellularization at high fidelity. In doing this work, we will also reveal how genes, mechanics, and environment regulate F-actin.

 描述（由适用提供）：细胞形状的变化驱动形态发生和肌动蛋白缺陷导致细胞形状变化和先天缺陷失败。然而，我们对肌动蛋白对形态发生的影响的了解在很大程度上仅限于分子列表和总表型的描述。虽然肌动蛋白丝（F-肌动蛋白）被认为是细胞形状的主要结构确定剂，但基本问题仍未得到解答：F-肌动蛋白如何重塑？它如何与细胞膜相互交互？它如何适应环境或遗传变异性？我们需要这些答案来了解发展和人类疾病。我们的长期目标是充分了解肌动蛋白在形成健康组织中的作用。我们专注于果蝇细胞化，该过程构建了胚胎中的第一张上皮片。在细胞化过程中，胚胎的每个新细胞中都在进行三个细胞表面重塑事件：（i）微绒毛拆卸； （ii）膜犁沟入口； （iii）Actomyosin环合同。我们已经表明，尽管这三个重塑事件经常被隔离在数十微米上，但它们仍然可以彼此耦合，并在肌动蛋白环中的可测量变化。我们还确定了肌动菌素环中特定的F-肌动蛋白调节剂，从而促进了细胞化对环境和遗传扰动的鲁棒性。这些结果表明，肌动蛋白不仅可以给细胞形状。我们的工作模型是，基于肌动蛋白的机制也有助于形态发生的协调，动力学和鲁棒性。在这项提出的工作中，我们将测试我们的模型如下：在AIM 1中，我们将检验以下假设：犁沟的吸收产生的质膜张力抑制了微维利中的F-肌动蛋白聚合，从而导致它们“展开”或崩溃。在AIM 2中，我们将检验他的假设，即肌动蛋白环收缩的不同动力学阶段受F-肌动蛋白调节的不同机制的控制。在AIM 3中，我们将检验以下假设：F-肌动蛋白调节剂SRYA和SPT稳定收缩环内的F-肌动蛋白，以确保在 环境和遗传扰动的面孔。我们组建了一个由物理学家，数学家和技术人员组成的跨学科团队；我们将采用强大的方法组合，包括定量的活成像，物理力测定，遗传学和基因组编辑，以罕见的细节检查细胞化事件。因为驱动细胞化的基于肌动蛋白的机械被广泛保守，所以我们的发现将与包括人类在内的其他器官有关。我们将确定如何在空间和时间上调节单个重塑事件，同时还显示事件如何相互协调以在高保真度下完成细胞化。在完成这项工作时，我们还将揭示基因，机械和环境如何调节F-肌动蛋白。