Examination of Curvature Selectivity as Core Parameter for Temporal and Spatial Protein Organization at Deforming Cellular Membranes

跨细胞膜的信号传播依赖于动态的分子平台，这些平台整合了细胞内和细胞外的信号来调节细胞的形状和功能。为了正确应对不断变化的环境，这些信令平台的活动需要在空间和时间上得到严格控制。我们实验室的工作集中在一种特定类型的受体非依赖性信号平台上，在这种平台上，质膜上的物理力通过纳米级的膜变形转化为经典的生化信号转导级联。这种新型的机械力-化学信号在细胞膜上的翻译依赖于曲率感应信号分子在瞬间变形的细胞膜上的动态募集。在拟议的项目中，我们的目标是研究负责创建功能不同的曲率依赖的信号枢纽的分子机制。具体地说，我们的目标是回答：(I)不同蛋白质膜曲率选择性的差异是否足以控制曲率感应信号蛋白在自发变形的质膜上出现的时间顺序。(Ii)如果单个蛋白质在膜曲率选择性上的差异会导致这些蛋白质在弯曲的膜上形成的聚集体中的不对称空间组织。为了解决这些问题，我们将在活细胞和人造膜中将新型纳米材料与先进的图像分析方法相结合。以肌动蛋白聚合动力学的曲率依赖调节为模型系统，研究空间和时间招募动力学差异对力化学信号转换的功能影响。这项拟议的项目是相关的，因为它将提供证据，证明曲率选择性足以组织曲率感知蛋白质在空间和时间上的定位，从而控制信号枢纽的蛋白质组成。这些研究将促进我们对膜曲率如何参与多种细胞过程的理解(如细胞运动、细菌致病以及囊泡内吞和融合)，并为更好地理解涉及曲率感知信号蛋白缺陷的疾病(如智力低下的srGAP3、脆性X综合征的寡聚精神分裂症)提供新的途径。

Signal propagation across cellular membranes relies on dynamic molecular platforms that integrate intra- and extracellular signals to regulate cell shape and function. To correctly respond to an ever-changing environment, activity of these signaling platforms needs to be tightly controlled in space and time. Work in our lab is focused on a particular sub-type of receptor-independent signaling platforms, where physical forces at the plasma membrane are translated into classical biochemical signal transduction cascades via nanoscale membrane deformations. This new type of mechano-chemical signal translation at cellular membranes relies on dynamic recruitment of curvature-sensing signaling molecules to transiently deformed membranes. In the proposed project, we aim to investigate the molecular mechanisms responsible for the creation of functionally distinct curvature-dependent signaling hubs. Specifically, we aim to answer: (I) Whether differences in membrane curvature selectivity of individual proteins are sufficient to control the temporal order in which curvature-sensing signaling proteins appear at a spontaneously deforming plasma membrane. (II) If differences in membrane curvature selectivity of individual proteins can lead to asymmetric spatial organization of these proteins in aggregates that form at curved membranes. To address these questions, we will combine novel types of nanomaterials with advanced image analysis methods in live cells and artificial membranes. Functional consequences of differences in spatial and temporal recruitment dynamics on mechano-chemical signal conversion will be investigated using curvature-dependent regulation of actin polymerization dynamics in lamellipodia and filopodia as model systems. The proposed project is relevant as it will provide evidence that curvature-selectivity is sufficient to organize localization of curvature-sensing proteins in space and time, and in consequence to control protein composition at signaling hubs. Insights from these studies will advance our understanding of how membrane curvature contributes to a variety of cellular processes, (e.g. cell motility, bacterial pathogenesis, as well as vesicle endocytosis and fusion), and provide new inroads to better understand disease involving defective curvature-sensing signaling proteins (e.g. srGAP3 in mental retardation, Oligophrenin in fragile X syndrome).