Spatial control of membrane traffic by septin GTPases

项目概要/摘要 膜运输的空间控制对于极化的细胞的形态发生和维持至关重要。 细胞类型，如上皮细胞和神经元，以及它们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肿瘤的发病机制的基础。 包括癌症、神经变性和代谢紊乱的疾病。我们研究的理由是， 膜交通的空间组织和调节的机械知识对于设计至关重要 新的治疗方法和再生疗法。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，在这方面， 关键的挑战仍然是了解远程运输如何在空间上受到控制， 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）和膜结构域的不同子集相关，包括一种新的调节性 膜交通的空间引导模块。我们实验室的最新发现表明， 调节运动（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septin功能和上皮细胞膜运输的空间控制的关键问题， 神经元我们将调查是否有特殊性septins和不同路线的极化交通 (e.g.,顶侧对基底侧）。我们将区分隔蛋白在MT的空间定向中的作用和在MT的空间定向中的作用。 MT轨道上运动运动的调制，这将与结构-功能的机制研究 接近。基于Septin与内溶酶体结合的新证据，我们将研究Septin如何与内溶酶体结合。 溶酶体运输和定位受septins调节。我们将检验内溶酶体 septins为动力蛋白-动力蛋白的募集和激活提供支架，并检查septins是否参与了 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 细胞膜是受控的，集中于通过信号激酶作为开关机制磷酸化septins MT和膜相关功能之间的联系。我们将使用创新工具来实施这些项目， 尖端的方法，包括体外重建，单分子和超分辨率显微镜， 和3D类器官培养。结果将提供新的见解的机制，直接运输的 膜囊泡和内溶酶体对形态发生和代谢信号的反应。拟议 研究还将促进我们对septins作为细胞内组织的空间调节剂的理解， 对由septin表达异常触发和/或加重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.