How Cells Control the Properties of Membraneless Organelles to Control Their Function

项目摘要-F32 Benjamin Stormo 无膜细胞器材料特性的控制使细胞能够控制其功能。 细胞如何排列和划分其细胞质是生物学中的一个关键问题。最近的工作有 发现许多细胞依赖于无膜细胞器。这些细胞器没有与其他细胞器分开 通过脂类双层作用于细胞。取而代之的是无膜细胞器依赖于一种称为液体的热力学过程- 液体相分离(LLP)，在此过程中，混合良好的溶液可以自发地分离成浓缩的 液滴相和稀相。这些类似液体的液滴在大气中具有许多重要的功能。 细胞包括RNA加工，改变反应动力学，以及在应激期间隔离转录物。水滴 具有许多可测量的生物物理特性，包括粘度、扩散率和渗透率。 有趣的是，在测量这些液滴的性质的情况下，它们会有很大的不同 在不同类型的液滴之间。尽管存在这些差异，但我们对 特性对于无膜细胞器的功能很重要，尽管有人提出 这种液滴特性的失调会导致阿尔茨海默氏症和亨廷顿病等疾病。关键是， 由于相分离是一个热力学过程，它受到细胞控制内的两个因素的影响： 即组分的浓度，以及电池外部的东西控制：即温度。 我们的工作旨在了解无膜细胞器的材料性质如何影响它们的功能。至 做到这一点，我们将寻找细胞控制液滴材料属性的证据 温度。我们实验室以前曾使用模型丝状真菌Ashbya Cotsypii来研究类液体 水滴。在阿什比亚，无膜细胞器是控制细胞周期和极化生长的关键。 使用这些清晰和相关的生理读数以及体外重建系统，我们寻求 了解无膜细胞器的特定材料属性是如何实现特定功能的 牢房。我们将使用从美国各地收集的独特的野生阿什比亚分离物来 解决两个具体目标：1)液滴成分的初级序列在不同分离物之间有何不同 来自不同的气候，以及这些序列变化如何影响产生的液滴。2)单元格如何 适应瞬变的温度变化，以保持体内液滴的特性。为了回答这些问题，我们 将使用高分辨率光学显微镜。 通过这项工作，我们将提高我们对细胞如何正常调节细胞特性的理解 无膜细胞器以及这种调节与细胞功能的关系。了解角色材料 液滴在正常功能下发挥的特性对于理解它们被改变时会发生什么至关重要 在阿尔茨海默氏症和亨廷顿病等疾病中。

Project Summary – F32 Benjamin Stormo The Control of Membraneless Organelles Material Properties Allows Cells to Control Their Function. How cells pattern and compartmentalize their cytoplasm is a critical question in biology. Recent work has discovered that many cells rely on membraneless organelles. These organelles are not separated from the rest of the cell by a lipid bilayer. Instead membraneless organelles rely on a thermodynamic process called Liquid- Liquid Phase Separation (LLPS) in which a well-mixed solution can spontaneously demix into a concentrated droplet phase and a dilute bulk phase. These liquid-like droplets perform a number of important functions in the cell including RNA processing, altering reaction kinetics, and sequestering transcripts during stress. Droplets have a number of measurable biophysical properties including viscosity, diffusivity, and permeability. Interestingly, in cases where the properties of these droplets have been measured they vary substantially between different types of droplets. Despite these difference we have very little understanding about whether specific properties are important for the function of membraneless organelles, although it has been suggested that dysregulation of droplet properties can result in diseases such as Alzheimer and Huntington. Critically, because phase separation is a thermodynamic process it is influenced by both things within the cells control: i.e. concentration of the components, and things outside of the cells control: i.e. temperature. Our work seeks to understand how the material properties of membraneless organelles affect their function. To do this we will look for evidence that cells control the material properties of droplets following changes in temperature. Our lab has previously used the model filamentous fungus Ashbya gossypii to study liquid-like droplets. In Ashbya membraneless organelles are critical for controlling the cell cycle and polarized growth. Using these clear and relevant physiological readouts along with an in vitro reconstitution system we seek to understand how specific material properties of membraneless organelles are required for specific function in the cell. We will use a unique collection of wild Ashbya isolates collected from around the United States to address two specific aims: 1) How do the primary sequences of droplet components vary between isolates from different climates and how do these sequence changes affect the resulting droplets. 2) How do cells adapt to transient temperature changes to maintain droplet properties in vivo. To answer these questions we will use high resolution light microscopy. Through this work we will improve our understanding of how cells normally regulate the properties of membraneless organelles and how this regulation relates to cellular function. Understanding the role material properties of droplets play in normal function is crucial for understanding what happens when they are altered in disease conditions such as Alzheimer and Huntington.