Tracking shallow and dynamic chemoattractant gradients - how yeast cells amplify both internal and external signals to locate mating partners

跟踪浅层和动态趋化剂梯度——酵母细胞如何放大内部和外部信号来定位交配伙伴

• 批准号: 2341919
• 负责人: David Stone
• 金额: $ 162.62万
• 依托单位: University of Illinois at Chicago
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-03-01 至 2028-02-29
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2341919&HistoricalAwards=false
• 关键词: Tracking; shallow; dynamic; chemoattractant; gradients

This project will contribute to our understanding of gradient sensing, the ability of cells to sense small differences in chemical concentration across their surfaces, and thereby locate the source of the stimulus. This phenomenon is essential for the development and health of all organisms. The PI uses yeast cells as a model to study the molecular mechanisms underlying gradient sensing, which are thought to be broadly applicable to cells in more complex organisms. In previous studies, he discovered a “gradient tracking machine” that cells must assemble before they are able to sense the direction of the chemical source. In this investigation, he will continue to investigate how this machine functions to decode chemical gradients. During this project period, the PI and his senior research specialist will mentor select biology students from the City Colleges of Chicago, to enhance their chances of graduating from a four-year institution with a BS in a STEM field. The proposed undergraduate research and mentoring program is designed to inspire, instruct, advise, and support underrepresented students who are interested in a STEM career. Two outstanding candidates will be chosen to participate each year based on their academic potential and motivation to pursue a STEM major at a four-year institution. By participating in regular tutoring sessions, paid summer research internships in the PI’s lab, and public outreach events, students will gain experience conducting scientific research, an ability to critically evaluate the research of others, and practice presenting their work. This program is expected to increase the chances of eight students to succeed as science majors at four-year institutions. The investigation will also provide the PI's students with interdisciplinary training through interactions with collaborators who are experts in diverse areas.The best-known gradient-stimulated cellular outputs, chemotaxis (directed cell movement), and chemotropism (directed cell growth), are required for a wide range of biological processes. Although they ultimately exhibit quite different behavior, chemotactic and chemotropic cells face similar challenges: the responding cell must sense small differences in chemical concentration across its surface, determine the direction of the gradient source, and polarize its cytoskeleton toward it. The mating response of the budding yeast S. cerevisiae is chemotropic: mating cells interpret complex pheromone gradients and polarize their growth in the direction of the closest partner. Like many chemosensing cells, yeasts use G protein-coupled receptors to detect chemoattractant. The goal of this project is to understand how yeast cells accurately sense direction in shallow, complex, and dynamic pheromone gradients. Based on discoveries made in a previous project, the PI published a deterministic model of gradient sensing that explains, in broad terms, how yeast cells translate a vanishingly small differential of activated receptors across their surfaces into accurate and robust directional responses. Mating yeast initially ignore the pheromone gradient, as they first colocalize signaling, polarity, and trafficking proteins to the default polarity site they use for budding, building a “gradient tracking machine” (GTM). Once assembled, the GTM moves along the plasma membrane to the point of maximal pheromone concentration, where it marks the chemotropic site used for mating. The primary negative regulator of G-protein signaling, the RGS protein Sst2, is essential for this process, and phosphorylation of one of the G-protein subunits (Gbetagamma)plays a critical role. The priorities of this investigation are to learn how Sst2 is controlled in space and time, how the phosphorylation of the G protein subunit contributes to gradient tracking, and how dynamic intercommunication between GTMs enables mating partners to orient toward a common fusion site. These questions will be answered using imaging, genetic, biochemical, proteomic, and computational approaches.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.

该项目将有助于我们对梯度灵敏度的理解，细胞在其表面上感觉到化学浓度的微小差异的能力，从而找到刺激的来源。这种现象对于所有组织的发展和健康至关重要。 PI使用酵母细胞作为模型来研究梯度敏感性的分子机制，这些机制被认为广泛适用于更复杂的组织中的细胞。在先前的研究中，他发现了一种“梯度跟踪机”，在细胞能够感觉到化学源方向之前必须组装。在这项投资中，他将继续研究该机器如何解码化学梯度。在这个项目期间，PI和他的高级研究专家将从芝加哥市城市学院的精神精选生物学专业的学生进行精神精选的学生，以增加他们从STEM领域拥有BS的四年制机构毕业的机会。拟议的本科研究和心理计划旨在启发，指导，建议和支持对STEM职业感兴趣的人数不足的学生。每年将根据他们的学术潜力和在为期四年的机构中攻读STEM专业的动机，将选择两名出色的候选人参加。通过参加定期辅导会议，在PI的实验室中进行夏季研究实习以及公共宣传活动，学生将获得进行科学研究的经验，具有认真评估他人研究的能力，并介绍他们的工作。预计该计划将增加八名学生在四年制机构的科学专业的成功机会。这项投资还将通过与潜水区专家的互动来为PI的学生提供跨学科的培训。最著名的梯度刺激的细胞输出，趋化性（定向细胞运动）和化学智质（有向细胞生长）是广泛的生物学过程所必需的。尽管它们最终暴露了完全不同的行为，但趋化性和趋化细胞面临类似的挑战：响应细胞必须感知化学浓度在其表面上的微小差异，确定梯度源的方向，并将其细胞骨架向其偏振。发芽酵母菌的交配反应是趋化性的：交配细胞解释复杂的信息素梯度，并在壁橱伴侣的方向上极化它们的生长。像许多化学效应细胞一样，酵母使用G蛋白偶联受体来检测趋化剂。该项目的目的是了解酵母细胞如何在浅，复杂和动态信息素梯度中准确感知方向。根据先前项目中的发现，PI发表了一个确定性的梯度感应模型，该模型以广义的方式解释了酵母细胞如何将跨表面激活受体的小差差转化为准确且可靠的方向响应。交配酵母最初忽略了信息素梯度，因为它们首先将信号传导，极性和运输蛋白与它们用于萌芽的默认极性站点进行了同步，建立了“梯度跟踪机”（GTM）。组装后，GTM沿着质膜移动到最大信息素浓度的点，在此标记用于交配的趋化位点。 G蛋白信号传导的主要负调节剂RGS蛋白SST2对于此过程至关重要，并且G蛋白亚基之一（GBETAGAGAMMA）的磷酸化起着至关重要的作用。这项投资的优先事项是了解如何在时空中控制SST2，G蛋白亚基的磷酸化如何有助于梯度跟踪，以及GTMS之间的动态互通如何使配对伙伴向公共融合位点方向朝向。这些问题将使用成像，遗传，生化，蛋白质组学和计算方法来回答。该奖项反映了NSF的法定任务，并使用基金会的知识分子优点和更广泛的影响来评估，被认为是宝贵的支持。