Spatial control of membrane traffic by septin GTPases

项目概要/摘要 膜交通的空间控制对于极化的形态发生和维持至关重要 上皮细胞和神经元等细胞类型及其在组织稳态中的生理功能 神经传递。细胞极性的丧失和膜运输的缺陷是许多疾病发病机制的基础 疾病包括癌症、神经退行性疾病和代谢紊乱。我们研究的基本原理是 膜交通空间组织和调节的机械知识对于设计至关重要 新疗法和再生疗法。在理解膜方面已经取得了许多进展 起点（蛋白质分选、囊泡形成）和目的地（囊泡对接/融合）的交通。然而， 主要挑战仍然在于理解远距离运输在前往目的地的途中如何进行空间控制。 目的地。我们的中心假设是 septins，一个独特的 GTP 结合蛋白家族， 与微管 (MT) 和膜域的不同子集相关，构成一种新的调节机制 膜交通空间引导模块。我们实验室的最新研究结果表明，脓毒症 调节运动蛋白（驱动蛋白、动力蛋白）与 MT 和膜的相互作用。在这些进步的推动下，我们将 解决有关隔膜功能和上皮细胞膜交通空间控制的关键问题 神经元。我们将研究脓毒症和极化流量的不同路线之间是否存在特异性 （例如，顶端与基底外侧）。我们将区分 MT 空间方向中的 septin 作用和 MT 轨道上运动运动的调制，将通过结构功能进行机械研究 接近。根据 Septin 与内溶酶体相关的新证据，我们将研究如何 溶酶体的运输和定位由脓蛋白调节。我们将检验内溶酶体的假设 septins 支持动力蛋白-dynactin 的募集和激活，并检查 septins 是否参与 驱动蛋白和动力蛋白马达的协调。最后，我们将研究 septin 如何与 MT 或 膜受到控制，重点是通过信号激酶作为开关机制来磷酸化脓蛋白 MT 和膜相关功能之间的关系。我们将使用创新工具和 尖端方法，包括体外重建、单分子和超分辨率显微镜， 和 3D 类器官培养。结果将为指导运输的机制提供新的见解 膜囊泡和内溶酶体响应形态发生和代谢信号。拟议的 研究还将加深我们对脓毒症作为细胞内组织空间调节器的理解， 对因 septin 表达异常引发和/或加剧的疾病具有重要意义。

Project Summary/Abstract Spatial control of membrane traffic is essential for the morphogenesis and maintenance of polarized cell types such as epithelia and neurons, and their physiological functions in tissue homeostasis and neurotransmission. Loss of cell polarity and defects in membrane traffic underlie the pathogenesis of many diseases including cancer, neurodegeneration and metabolic disorders. The RATIONALE for our studies is that a mechanistic knowledge of the spatial organization and regulation of membrane traffic is critical for the design of new treatments and regenerative therapies. Many advances have been made in understanding membrane traffic at points of origin (protein sorting, vesicle formation) and destination (vesicle docking/fusion). However, KEY CHALLENGES remain in understanding how long-range transport is spatially controlled en route to destination. Our CENTRAL HYPOTHESIS is that septins, a unique family of GTP-binding proteins that associate with distinct subsets of microtubules (MTs) and membrane domains, comprise a novel regulatory module for the spatial guidance of membrane traffic. Recent findings from our laboratory show that septins modulate motor (kinesins, dynein) interactions with MTs and membranes. Driven by these advances, we will address KEY QUESTIONS about septin functions and the spatial control of membrane traffic in epithelia and neurons. We will investigate whether there is specificity between septins and distinct routes of polarized traffic (e.g., apical vs. basolateral). We will distinguish between septin roles in the spatial orientation of MTs and the modulation of motor motility on MT tracks, which will be mechanistically studied with structure-function approaches. Based on new evidence of septin association with endolysosomes, we will investigate how lysosome trafficking and positioning is regulated by septins. We will test the hypothesis that endolysosomal septins scaffold the recruitment and activation of dynein-dynactin, and examine whether septins are involved in the coordination of kinesin and dynein motors. Lastly, we will investigate how septin association with MTs or membranes is controlled, focusing on phosphorylation of septins by signaling kinases as a switch mechanism between MT- and membrane-associated functions. We will pursue these projects using innovative tools and cutting-edge approaches including in vitro reconstitution, single-molecule and super-resolution microscopy, and 3D organoid culture. Outcomes will provide new insights into the mechanisms that direct the transport of membrane vesicles and endolysosomes in response to morphogenetic and metabolic signals. The proposed studies will also advance our understanding of septins as spatial regulators of intracellular organization, bearing significance on diseases triggered and/or exacerbated by abnormalities in septin expression.