CAREER: Elucidating acentrosomal microtubule organization by integrating cell biology, single molecule imaging and computational modeling

细胞形状的控制是生命的基本属性，对所有生物体的形式和功能都是必不可少的。细胞形状主要由称为细胞骨架的内部支架结构控制。与人造支架结构不同，细胞骨架是高度动态的，能够根据发育和环境信号改变其结构，使细胞能够适应不断变化的条件。该项目使用植物的皮质微管细胞骨架作为模型，以了解在缺乏集中组织机制的情况下，微管聚合物如何形成高度有序的阵列。通过整合从单分子到整个细胞的方法，这项研究将揭示分子水平上的生化活动导致细胞水平上的复杂微管阵列的原理，预计该原理也适用于其他此类阵列。由于植物皮质微管阵列指导细胞壁组装，这项工作也可能导致新的策略，以工程植物生物量，以改善食品和纤维素生物燃料生产。该项目的工作将通过在K-20教育领域的多个层次开展以调查为基础的活动，纳入教育和外联工作。具体地说，PI将把这项工作纳入建筑系学生的一门课程，以启发基于细胞设计原理的新的人造结构，以及一个新的生物自组织专业发展研讨会，为高中教师提供数学生物资源，帮助他们满足下一代科学标准。他还将把这个项目的工作整合到一个基于问题的青少年科学咖啡馆项目中，该项目每年吸引1,000-1,500名6-12年级的学生，是教授科学探究过程和动态细胞事件的绝佳机会。PI将研究非中心体微管如何在没有组织中心的情况下形成高度有序的阵列。这个问题很重要，因为非中心体微管阵列对于进化上不同的生物，如分裂酵母、人类和植物的结构和功能至关重要。为了阐明潜在的机制，PI将使用拟南芥植物的皮质微管细胞骨架作为实验上易于处理的模型系统。PI假设多个微管相关蛋白的净平衡通过调节皮质微管的轨迹、长度和动力学来动态地控制阵列结构。为了验证这一假说，将使用现场成像、单分子分辨率的体外实验和计算建模相结合的方法：1)确定EB1及其相关蛋白在调节皮质微管行为中的功能；2)研究微管捆绑在阵列组织中的作用；3)确定不同的分子活动如何在空间和时间上相互作用以动态形成皮质微管的图案；以及4)阐明定义和改变皮质微管阵列方向以响应发育和环境信号的机制。总之，这项研究将促进我们对如何构建不同的皮质微管阵列以创建不同的细胞形状，以及如何根据信号重塑阵列以改变植物生长的理解。该项目的工作将被整合到多项教育和推广活动中，将新的生物学概念和技术引入课堂，并使学生对从事STEM职业感兴趣。PI将把这项工作纳入建筑系学生的一门课程，以启发基于蜂窝建筑基本原理的新建筑设计。PI还将为高中教师领导一个关于生物自组织的专业发展研讨会，该研讨会将结合动手活动和计算机建模，提供可带回课堂的数学生物资源。他还将把这个项目的工作整合到一个以问题为基础的青少年科学咖啡馆项目中，该项目面向6-12年级的学生，教授科学探究过程和动态细胞事件。

Control of cell shape is a fundamental property of life, essential to the form and function of all organisms. Cell shape is governed primarily by an internal scaffolding structure called the cytoskeleton. Unlike human-made scaffolding structures, the cytoskeleton is highly dynamic and is able to change its configuration in response to developmental and environmental signals, allowing cells to adapt to changing conditions. This project uses the cortical microtubule cytoskeleton of plants as a model to understand how microtubule polymers form highly ordered arrays in the absence of a centralized organizing mechanism. By integrating approaches scaling from single molecules to whole cells, this research will reveal principles by which biochemical activities at the molecular scale result in complex microtubule arrays at the cellular scale, principles expected to be applicable to other such arrays. Since the plant cortical microtubule array directs cell wall assembly, this work might also lead to new strategies to engineer plant biomass for improved food and cellulosic biofuel production. The work from this project will be integrated into education and outreach through inquiry-based activities at multiple levels across the K-20 education spectrum. Specifically, the PI will incorporate this work into a course for Architecture students to inspire new human-made structures based on cellular design principles and a new professional development workshop on Biological Self-Organization to provide high-school teachers with a mathematical biology resource to help them meet the Next Generation Science Standards. He will also integrate work from this project into a problem-based Teen Science Café program, which attracts between 1,000-1,500 students from grades 6-12 annually and is a great opportunity to teach the scientific inquiry process and about dynamic cellular events.The PI will study how noncentrosomal microtubules form highly ordered arrays without the benefit of an organizing center. This problem is fundamentally important because noncentrosomal microtubule arrays are vital for the structure and function of evolutionarily diverse organisms such as fission yeast, humans and plants. To elucidate the underlying mechanisms, the PI will use the cortical microtubule cytoskeleton of Arabidopsis thaliana plants as an experimentally tractable model system. The PI hypothesizes that the net balance of multiple microtubule-associated proteins dynamically controls array structure by regulating the trajectory, length and dynamics of cortical microtubules. To test this hypothesis, a combination of live imaging, in vitro experiments at single molecule resolution and computational modeling will be used to: 1) determine the function of EB1 and associated proteins in regulating the behavior of cortical microtubules, 2) investigate the role of microtubule bundling in array organization, 3) determine how distinct molecular activities interact in space and time to dynamically pattern cortical microtubules, and 4) elucidate the mechanisms that define and change cortical microtubule array orientation in response to developmental and environmental signals. Together, this research will advance our understanding of how distinct cortical microtubule arrays are built to create different cell shapes and how arrays are remodeled in response to signals to modify plant growth. The work from this project will be integrated into multiple education and outreach activities to introduce new biological concepts and techniques into classrooms and to get students interested in pursuing a STEM career. The PI will incorporate this work into a course for Architecture students to inspire new architectural designs based on principles underlying cellular architecture. The PI will also lead a professional development workshop on Biological Self-Organization for high-school teachers, which will combine hands-on activities and computer modeling to provide a mathematical biology resource to take back to classroom. He will also integrate work from this project into a problem-based Teen Science Café program for students from grades 6-12 to teach the scientific inquiry process and about dynamic cellular events.