Spatial control of membrane traffic by septin GTPases

项目摘要/摘要 膜交通的空间控制对于极化的形态发生和维持是必不可少的 细胞类型，如上皮和神经元，以及它们在组织动态平衡和 神经传递。细胞极性的丧失和膜运输的缺陷是许多 疾病包括癌症、神经退行性变和代谢紊乱。我们研究的理由是 对膜交通的空间组织和调节的机械知识对设计至关重要 新的治疗方法和再生疗法。对膜的认识已经取得了许多进展 原产地(蛋白质分选、囊泡形成)和目的地(囊泡对接/融合)的交通。然而， 关键挑战仍然是理解长距离运输在空间上受到多大程度的控制 目的地。我们的中心假设是Septins，一个独特的GTP结合蛋白家族，可以 与微管(MT)和膜域的不同亚组相结合，包括一种新的调节 用于膜上交通空间诱导的模块。我们实验室的最新发现表明，七叶皂苷 调节运动(动蛋白、动力蛋白)与MTS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。我们将调查间隔蛋白和两极分化交通的不同路线之间是否存在特异性 (例如，根尖与基底外侧)。我们将区分Septin在MTS空间定向中的作用和 MT轨道上电机运动的调节，将从结构-功能的角度进行力学研究 接近了。基于Septin与内溶酶体相关的新证据，我们将研究 溶酶体的运输和定位受Septins的调控。我们将检验内溶酶体的假设 Septins为dynein-dynactin的募集和激活提供了支架，并检测是否参与了 动蛋白和动力蛋白马达的协调。最后，我们将研究Septin与MTS或 膜被控制，集中在通过信号转导激酶作为开关机制的Septins的磷酸化。 MT相关功能和膜相关功能之间的关系。我们将使用创新的工具和 包括体外重建、单分子和超分辨率显微镜在内的尖端技术， 和3D器官培养。结果将为指导运输的机制提供新的见解 膜小泡和内溶体对形态发生和代谢信号的响应。建议数 研究还将促进我们对Septins作为细胞内组织的空间调节因子的理解， 对由Septin表达异常引发和/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.