Deciphering the functional role of actin-spectrin-based membrane skeleton in subcellular compartmentalization of signaling proteins and cell signal transduction

项目概要/摘要： 受体酪氨酸激酶（RTK）、G蛋白偶联受体（GPCR）和细胞粘附 CAM分子是所有真核细胞中细胞表面蛋白的三个主要家族， 一起表示细胞响应细胞外刺激的主要第一应答者， 启动多种信号传导途径以随后调节细胞增殖， 分化，促进细胞存活，并调节细胞代谢和细胞与细胞的相互作用。 通信影响这些信号通路的突变导致许多人类综合征 和疾病，例如各种类型的神经变性病症和癌症。临床 这些信号蛋白的重要性促使了靶向治疗的发展 设计来阻断膜受体的激活和下游信号 转导越来越多的证据表明，存在显著的信号串扰 这三种膜蛋白家族在质膜水平上的差异， 可以形成高度组织化的膜微或纳米簇， 生物物理性质，决定信号结果。然而， 这种膜相关信号蛋白的相互作用和区室化 被启动来调节下游信号传导的敏感性和特异性， 难以捉摸。我们最近发现了一种新鉴定的肌动蛋白-血影蛋白为基础的膜相关蛋白， 周期性骨架（MPS）结构是通过GPCR进行RTK反式激活的信号平台 神经元中的CAMs提供了分子上的见解， 细胞表面蛋白质可以被协调以产生下游信号传导。客观 该提案的一个重要目的是将超分辨率成像、细胞和分子生物学工具相结合， 质谱分析，以调查负责的详细分子机制 MPS介导的细胞信号传导，通过确定负责的关键分子相互作用， MPS依赖性的信号蛋白聚簇的起始（即，复合物形成）和 检查液-液相分离、受体内吞作用和接触位点的作用 质膜和细胞内膜结合的细胞内细胞器之间的 MPS介导的信号传导。我们提出的研究不仅将扩大我们的基本 理解细胞信号转导受膜骨架和时相控制 信号蛋白的分离行为，也有助于为人类提供新的药物靶点。 包括神经变性疾病和癌症的疾病。

Project Summary/Abstract: Receptor tyrosine kinases (RTKs), G-protein-coupled receptors (GPCRs), and cell adhesion molecules (CAMs) are three major families of cell surface proteins in all eukaryotic cells, and together represent the primary first responders for cells to respond an extracellular stimulus and initiates a variety of signaling pathways to subsequently regulate cell proliferation and differentiation, promote cell survival, and modulate cellular metabolism and cell-to-cell communication. Mutations affecting these signaling pathways result in many human syndromes and diseases, such as various types of neurodegenerative disorders and cancer. The clinical importance of these signaling proteins has motivated the development of targeted therapies designed to block the activation of the membrane receptors and the downstream signal transduction. Increasing evidence has suggested that there is significant signaling crosstalk between these three membrane protein families at the plasma membrane level and these proteins can form highly organized membrane micro- or nano-clusters with unique biochemical and biophysical properties, dictating the signaling outcome. However, the molecular mechanisms by which how such crosstalk and compartmentalization of membrane-associated signaling proteins are initiated to modulate the sensitivity and specificity of the downstream signaling remain largely elusive. Our recent discovery of a newly identified actin-spectrin-based membrane-associated periodic skeleton (MPS) structure being a signaling platform for RTK transactivation by GPCRs and CAMs in neurons provides molecular insights into how the cooperative action among these cell surface proteins can be coordinated to give rise to the downstream signaling. The objective of this proposal is to combine super-resolution imaging, cell and molecular biology tools, and mass spectrometry analyses, to investigate the detailed molecular mechanisms responsible for the MPS-mediated cell signaling, by identifying the key molecular interactions responsible for the MPS-dependent initiation of the signaling protein clustering (i.e., complex formation) and examining the roles of liquid-liquid phase separation, receptor endocytosis, and contact sites between the plasma membrane and intracellular membrane-bound intracellular organelles in the MPS-mediated signaling. Our proposed research will not only broaden our fundamental understanding of cell signal transduction controlled by the membrane skeleton and the phase separation behaviors of signaling proteins, but also help suggest new drug targets for human diseases including neurodegenerative diseases and cancer.