Elucidating the Mechanism in the Regulation of RNA-binding Protein Phase Separation

摘要： RNA结合蛋白（RBP）的液-液相分离是最近受到重视的细胞内分离方法。 区室化是各种无膜细胞器生物发生的基础。尽管生物学上 利用，RNA结合蛋白（RBP）的相分离失调导致蛋白质聚集和原纤维 形成，这是许多神经退行性疾病的关键病理特征。核心假设 我的工作，我的实验室的驱动力，是逆转异常相变和聚合是一个 这是对抗这些致命疾病的潜在途径。事实上，我们和其他国家已经确定， Kapβ2等近红外受体可逆转蛋白质的异常相变和Kapβ2的高表达 可以抑制由疾病相关RNA结合蛋白引起的神经变性。因此，NIR和其他 蛋白质相变的调节剂可以在治疗上被利用来恢复正常的功能， 无膜细胞器和减轻异常相变引起的蛋白毒性。然而，几个关键 必须填补有关相变调节的知识空白，为发展这种 治疗策略因此，我的研究计划的长期目标是实现更全面的 了解蛋白质相分离的调节机制，并利用我们对 阶段调节，以开发具有治疗潜力的策略来逆转由异常的 相变我试图阐明调节蛋白质相分离的分子机制， 在健康和疾病状况。 我们建议在未来五年内重点关注三个主题：（1）定义Kapβ2 逆转蛋白质的异常相变。(2)确定Kapβ2和其他核输入的范围和特异性 受体在调节活细胞中的相分离中的功能。(3)根据我们的初步结果， 具有特定序列的RNA寡核苷酸在调节RNA结合蛋白时相方面具有多种活性 分离，我们将确定RNA在调节RBP相分离中的序列空间， 创新的基于单分子荧光的生物物理方法，以了解RNA的机制 功能我们的工作将大大有助于我们了解的调控机制相 细胞中的分离以及这种调节的破坏如何导致疾病。此外，这项工作 将为开发增强Kapβ2活性的策略以及基于RNA的 寡核苷酸，可以减轻毒性异常相变，这两者都提供了基础， 创新疗法，以恢复细胞中的健康蛋白质阶段。

Abstract: Liquid–liquid phase separation of RNA-binding proteins (RBP) is a recently appreciated means of intracellular compartmentalization underpins the biogenesis of diverse membraneless organelles. Despite clear biological utility, dysregulated phase separation of RNA-binding protein (RBP) leads to protein aggregation and fibrils formation, which are key pathological features of numerous neurodegenerative diseases. The central hypothesis of my work, and the driving force of my lab, is that reversing aberrant phase transition and aggregation is a potential avenue to combat these fatal diseases. In fact, we and others have established that nuclear import receptors (NIRs) such as Kapβ2 can reverse protein aberrant phase transition and elevated Kapβ2 expression can suppress neurodegeneration caused by disease-linked RNA-binding proteins. Thus, NIRs and other regulators of protein phase transition could be leveraged therapeutically to restore normal function of membraneless organelles and mitigate proteotoxicity caused by aberrant phase transition. However, several key knowledge gaps regarding the regulation of phase transition must be filled, to lay the foundation to develop such therapeutic strategies. Thus the long-term goal of my research program is to achieve a more comprehensive understanding of the regulatory mechanism of protein phase separation and leverage our understanding of phase regulation to develop strategies with therapeutic potential to reverse proteotoxicity induced by aberrant phase transition. I seek to elucidate the molecular mechanism of the regulation of protein phase separation, both in health and disease conditions. We propose to focus on three main themes over the next five years: (1) Define the mechanism of how Kapβ2 reverses protein aberrant phase transition. (2) Define the scope and specificity of Kapβ2 and other nuclear import receptors in their function in regulating phase separation in live cells. (3) Based on our preliminary results that RNA oligonucleotides with specific sequences have diverse activities in regulating RNA-binding protein phase separation, we will identify the sequence space of RNA in regulating RBP phase separation and develop innovative single-molecule fluorescence-based biophysical methods to understand the mechanism of RNA’s function. Our work will significantly contribute to our understanding of the regulatory mechanism of phase separation in cells and how the breakdown of this regulation leads to disease conditions. Furthermore, this work will set the stage for developing strategies to enhance the activity of Kapβ2, as well as RNA-based oligonucleotides that can mitigate toxic aberrant phase transition, both of which provide the basis for developing innovative therapeutics to restore the healthy protein phase in cells.