CAREER: Contact inhibition of locomotion as a positioning mechanism during endoderm morphogenesis

在多细胞生物体中，组织、器官，甚至整个身体的计划都是通过许多单个细胞的行动来建立的。了解细胞如何相互协调它们的活动仍然是生物学中的一个悬而未决的问题。这项研究将利用斑马鱼的胚胎来了解一群名为内胚层细胞的胚胎细胞如何协同工作来构建最终将成为胃肠道和呼吸系统一部分的组织。在人类中，内胚层畸形估计每10,000名新生儿中就有10名受到影响。斑马鱼胚胎将用于这项研究，因为它们是透明的，并在外部(母亲之外)发育，因此很容易想象一个活的、完整的有机体内的细胞相互作用。初步研究表明，与直觉相反的是，斑马鱼内皮细胞在重新聚集形成组织之前会分散开来。这项研究旨在了解内皮细胞在组织形成过程中如何以及为什么经历这两种截然不同的行为(分散和会聚)。这项研究将与教育和推广计划相结合，旨在扩大获得真实研究经验的机会，并加强本科生和普通公众的STEM教育。这一教育和推广计划包括：1)为加州大学默塞德分校的学生提供基于课程的本科生研究体验(CURE)；2)暑期计划，让本科生直接体验研究实验室中独立项目的工作；3)为当地一家儿童博物馆与培训教师合作设计的发育生物学和显微镜教育展览。内胚层是形成肠道和呼吸道上皮和其他器官的三个主要胚层之一。然而，内胚层细胞在原肠形成期间和分化为成熟上皮之前是高度迁移的。这项研究将利用斑马鱼胚胎在体内成像的适应性来表征细胞从迁移的内胚层前体分化为上皮细胞时发生的一系列细胞行为。在原肠发育阶段，斑马鱼内皮细胞首先彼此分散，然后最终会聚成一层连贯的上皮层。初步研究表明，内皮细胞最初通过接触触发的运动抑制来避开彼此。这项研究将确定驱动这些抑制相互作用的分子机制及其对组织形成的意义。目标1将识别允许内皮细胞识别和排斥彼此的细胞表面受体。目的2将确定调节抑制反应和内皮细胞初始扩散的细胞内信号通路。目标3将确定当细胞从分散运动切换到融合运动时，这些抑制相互作用是如何调节的。这项研究将展示瞬时的、超局部的细胞-细胞相互作用如何导致大规模的图案形成，并对组织形态发生产生广泛的影响。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

In multicellular organisms, tissues, organs, and even the entire body plan are built through the actions of many individual cells. Understanding how cells coordinate their actions with each other remains an outstanding question in biology. This study will use zebrafish embryos to understand how a population of embryonic cells called endodermal cells work together to build a tissue that will eventually become parts of the gastrointestinal and respiratory systems. In humans, endoderm malformations affect an estimated 10 per 10,000 births. Zebrafish embryos will be used in this study because they are transparent and develop externally (outside the mother), making it easy to image cellular interactions within a living, intact organism. Preliminary work suggested that, counterintuitively, zebrafish endodermal cells disperse apart before coming back together to form a tissue. This study aims to understand how and why endodermal cells undergo these two very different behaviors (dispersal and convergence) during tissue formation. This research will be integrated with an education and outreach program designed to expand access to authentic research experiences and enhance STEM education for undergraduate students and the general public. This education and outreach program consists of: 1) a course-based undergraduate research experience (CURE) for students enrolled at the University of California, Merced, 2) a summer program that will give undergraduate students direct experience working on an independent project in a research lab, and 3) an educational exhibit on developmental biology and microscopy for a local children’s’ museum designed in partnership with teachers-in-training.The endoderm is one of the three primary germ layers that gives rise to the gut and respiratory epithelia and other organs. However, endodermal cells are highly migratory during gastrulation and before differentiating into mature epithelia. This study will take advantage of the zebrafish embryo’s amenability for in vivo imaging to characterize the continuum of cellular behaviors that occur as cells differentiate from migratory endodermal precursors into epithelial cells. During gastrulation stages, zebrafish endodermal cells first disperse away from each other before eventually converging into a coherent epithelial sheet. Preliminary studies suggested that endodermal cells initially avoid each other through contact-triggered inhibition of locomotion. This study will determine the molecular mechanisms driving these inhibitory interactions and their significance to tissue formation. Aim 1 will identify the cell surface receptors that allow endodermal cells to recognize and repel away from each other. Aim 2 will define the intracellular signaling pathways that regulate inhibitory responses and the initial dispersal of endodermal cells. Aim 3 will determine how these inhibitory interactions are modulated as cells switch from dispersal to convergence movements. This study will demonstrate how transient, hyperlocal cell-cell interactions can lead to large-scale patterning, with broad implications for tissue morphogenesis.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.