MECHANISMS OF CELL POLARITY ESTABLISHMENT

细胞极性建立机制

• 批准号: 7932406
• 负责人: IAN G MACARA
• 金额: $ 6万
• 依托单位: UNIVERSITY OF VIRGINIA
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-30 至 2010-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7932406
• 关键词: Address; Antigen Presentation; Apical; Behavior; Binding; Brain; CDC42 gene; CNTNAP1 gene; Cell Polarity; Cell division; Cell physiology; Cell-Cell Adhesion; Cells; Cellular Morphology; Cellular Structures; Cyst; Data; Dendritic Spines; Environment; Epithelial Cells; Escherichia coli; Event; Exhibits; Face; Funding; GTP-Binding Proteins; Generations; Germ Cells; Grant; Guanosine Triphosphate Phosphohydrolases; Hippocampus (Brain); Human; Life; Link; MDCK cell; Malignant Neoplasms; Memory; Modeling; Molecular; Monomeric GTP-Binding Proteins; Morphogenesis; Neurons; Organism; PARD6A gene; Pathway interactions; Process; Property; Proteins; RNA Interference; Role; Saccharomycetales; Signal Pathway; Signal Transduction; Stem cells; Surface; Synapses; System; TIAM1 gene; Testing; Work; axon guidance; base; cell motility; cell type; cellular imaging; human JTB protein; insight; interest; novel; public health relevance; rho; rho GTP-Binding Proteins; rho GTPase-activating protein; tumor progression

DESCRIPTION (provided by applicant): Cell polarization is one of the most fundamental organizational aspects of life, from single-celled organisms such as E. coli and budding yeast up to the wiring of the human brain. Cell polarization is required for the generation of diverse cell types from stem cells, for morphogenesis, directional motility, antigen presentation, and axon guidance; and the loss of cell polarity is a critical step in cancer progression. The wide interest in cell polarity has pushed rapid progress in understanding the scope and complexity of the polarization machinery. However, the fundamental question of how the polarity proteins operate to organize cell structure remains largely unanswered. This proposal builds on progress over the last funding period to address these questions. Our objective is to understand the connections between the PAR polarity proteins and small GTPases. We will focus on MDCK epithelial cell polarization in 3D cultures, and on dendritic spine morphogenesis in hippocampal neurons - two tractable systems in which the PAR proteins have defined but distinct roles. The specific aims are as follows: 1. Identify the molecular mechanisms through which PAR-3, PAR-6, and aPKC organize the apical domain (which we term a "patch") during polarized cyst formation of MDCK cells. Using live cell imaging, we will investigate the earliest steps in polarization, which occur during the initial cell division of cells grown in 3D cultures. We will test a new model in which cytokinetic events are proposed to generate the landmark for apical patch assembly. 2. Determine the role of CDC42 in assembly of the apical patch, and identify the CDC42 GEF and GAP that are necessary for cell polarization. RNAi screens are being used to identify the GEF and GAP. Based on preliminary data from a GEF RNAi screen, we propose that a CDC42-GEF called Tuba drives recruitment of PAR-6/aPKC and apicalization. 3. Identify the mechanisms by which PAR-3 controls TIAM1 function in neurons; and determine how PAR- 6, independently of PAR-3, regulates dendritic spine morphogenesis via the Rho GTPase. We will determine the molecular basis for activation of p190 RhoGAP by PAR-6/aPKC. The mechanism by which PAR-6 regulates synaptic activity in hippocampal neurons will also be investigated. Together, these studies will provide new insights into the fundamentally important process of cell polarization, and into the ways by which the PAR polarity proteins exhibit context-specific behavior to control different aspects of cell morphology. PUBLIC HEALTH RELEVANCE: Over 90% of all human cancers originate from epithelial cells. A key property of epithelial cells is that they adhere to one another to form sheets in which the upper surface (which faces the environment) is functionally different from the bottom surface. Cancer progression involves the temporary loss of this cell-cell adhesion, and of up-down polarity. Thus, to understand human cancer, and to identify new chemotherapeutic targets, it is important to find out how epithelial cells polarize. Remarkably, the same process that helps these cells stick to one another is also essential for making the contacts between nerve cells in the brain, which enable us to think and store memories. This grant investigates the detailed molecular mechanisms that enable epithelial cells and nerve cells to polarize and form junctions, and will provide new insights into these mechanisms.

描述（由申请人提供）：细胞极化是生命最基本的组织方面之一，从单细胞生物如E。大肠杆菌和芽殖酵母直到人类大脑的布线。细胞极化是从干细胞产生不同细胞类型所必需的，用于形态发生、定向运动、抗原呈递和轴突引导;细胞极性的丧失是癌症进展中的关键步骤。对细胞极性的广泛兴趣推动了对极化机制的范围和复杂性的理解的快速进展。然而，极性蛋白如何组织细胞结构的基本问题在很大程度上仍然没有答案。本提案是在上一个供资期间为解决这些问题而取得的进展的基础上提出的。我们的目标是了解PAR极性蛋白和小GTP酶之间的联系。我们将专注于MDCK上皮细胞极化的三维文化，并在海马神经元树突棘形态发生-两个易于处理的系统中，PAR蛋白的定义，但不同的角色。具体目标如下：1.鉴定PAR-3、PAR-6和aPKC在MDCK细胞极化囊肿形成过程中组织顶端结构域（我们称之为“斑块”）的分子机制。使用活细胞成像，我们将研究极化的最早步骤，这发生在3D培养物中生长的细胞的初始细胞分裂期间。我们将测试一个新的模型，其中提出了细胞动力学事件，以产生顶端补丁组装的标志。2.确定CDC 42在根尖片组装中的作用，并鉴定细胞极化所必需的CDC 42 GEF和GAP。RNAi筛选被用于鉴定GEF和GAP。基于来自GEF RNAi筛选的初步数据，我们提出称为Tuba的CDC 42-GEF驱动PAR-6/aPKC的募集和顶端化。3.确定PAR-3控制神经元中TIAM 1功能的机制;并确定PAR- 6如何独立于PAR-3通过Rho GT3调节树突棘形态发生。我们将确定PAR-6/aPKC激活p190 RhoGAP的分子基础。PAR-6调节海马神经元突触活动的机制也将被研究。总之，这些研究将提供新的见解细胞极化的根本重要的过程，并进入PAR极性蛋白表现出特定的行为，以控制细胞形态的不同方面的方式。公共卫生相关性：超过90%的人类癌症起源于上皮细胞。上皮细胞的一个关键特性是它们彼此粘附以形成薄片，其中上表面（其面向环境）在功能上不同于底表面。癌症进展涉及这种细胞-细胞粘附和上下极性的暂时丧失。因此，为了了解人类癌症，并确定新的化疗靶点，重要的是要找出上皮细胞是如何增殖的。值得注意的是，帮助这些细胞相互粘附的过程对于大脑中神经细胞之间的联系也是必不可少的，这使我们能够思考和存储记忆。这项资助研究了使上皮细胞和神经细胞能够生长并形成连接的详细分子机制，并将为这些机制提供新的见解。