Elucidating the roles for discrete actin filaments in maintenance of organelle and cellular homeostasis

项目摘要：细胞骨架由肌动蛋白细丝、微管和中间体组成。 细丝在细胞器动力学中扮演着重要的角色，包括定位、运输和串扰。而当 微管因其在调节几个细胞器的动力学中的作用而被显著地定义 包括内质网和线粒体在内的肌动蛋白细丝在动力学和相互作用中的作用 内质网和线粒体的关系在很大程度上还没有得到充分的研究。培养细胞中可见的主要肌动蛋白结构 哺乳动物细胞包括皮质肌动蛋白、应力纤维和前缘的细丝(片层)。 它的主要功能是产生力量。然而，在这些压倒性的结构之下，是无数 不同的和动态的肌动蛋白细丝池，它们与不同的细胞器和 其在细胞器和细胞生理学中的作用尚未被探索。我的研究探索了两个这样的 肌动蛋白结构。其中一个在内质网周围组装，由内质网结合的肌动蛋白组装因子聚合， INF2.另一个池严格围绕Arp2/3复合体介导的功能障碍的线粒体进行聚合 和形成FMNL。我的研究表明，这两种肌动蛋白结构都是由一组不同的肌动蛋白聚合而成 组装因素和影响内质网和线粒体的动力学和相互作用的对比方式。然而， 这些不同的肌动蛋白细丝池的潜在机制和下游后果 细胞器和整体细胞生理学仍有待定义。我提议的工作将统一两者的概念 肌动蛋白动力学和细胞器生物学领域，从机械和功能上理解 这些肌动蛋白细丝在控制内质网和线粒体的生物学、动力学和串扰方面发挥着特定的作用。我的 拟议的研究计划将解决以下关键问题：1)动态肌动蛋白池如何发挥关键作用 内质网-线粒体串扰的调节；2)内质网相关的肌动蛋白细丝如何调节内质网功能， 3)这些动态肌动蛋白池对细胞内稳态有什么不同的细胞效应。 我的研究计划的总体目标是识别、描述和理解这些动态的角色 肌动蛋白池在调节各种细胞过程中发挥作用，这些过程特别与细胞器动力学和 串扰，严重区分它们，并将它们从大脑皮层的功能后果中分离出来 肌动蛋白细胞骨架。在未来，我们的目标是应用这些概念来理解细胞器动力学中的变化。 在不同病理系统中，希望通过这些扰动进行特定的治疗干预 特定的肌动蛋白细丝及其相关的组装因子和其他肌动蛋白结合蛋白。

Project Summary: The cytoskeleton comprised of the actin filaments, microtubules and the intermediate filaments plays important roles in organelle dynamics including positioning, transport, and crosstalk. While the microtubules have been significantly defined for their roles in regulating the dynamics of several organelles including Endoplasmic Reticulum (ER) and mitochondria, the role of actin filaments in dynamics and interactions of the ER and mitochondria is largely under-studied. The dominant actin structures visible in a cultured mammalian cell include the cortical actin, the stress fibers, and the filaments at the leading edge (lamellipodia) whose prime function is to generate force. However, underneath these overwhelming structures are a myriad of distinct and dynamic pools of actin filaments which are specifically associated with different organelles and whose role in organelle and cellular physiology have not been explored. My research has explored two such actin structures. One of them assembles around the ER, polymerized by an ER-bound actin assembly factor, INF2. The other pool polymerizes strictly around dysfunctional mitochondria mediated by the Arp2/3 complex and formin FMNL. My research showed that both these actin structures are polymerized by distinct set of actin assembly factors and affected ER and mitochondrial dynamics and interactions in contrasting ways. However, the underlying mechanisms and the downstream consequences of these distinct pools of actin filaments on the organelles and overall cellular physiology remain to be defined. My proposed work will unify concepts from both the fields of actin dynamics and organelle biology to understand, both mechanistically and functionally, the specific roles these actin filaments play in controlling ER and mitochondrial biology, dynamics, and crosstalk. My proposed research plan will tackle the following key questions: 1) How do dynamic actin pools act as key regulators of ER-mitochondrial crosstalk; 2) How does the ER associated actin filaments regulate ER function, and 3) What are the distinct cellular effects of these dynamic actin pools on cellular homeostasis. The overall goal of my research program is to identify, characterize and understand the roles that these dynamic pools of actin play in regulating various cellular processes specifically related to organelle dynamics and crosstalk, critically differentiating, and uncoupling them from being the functional consequences of the cortical actin cytoskeleton. In the future we aim to apply these concepts in understanding alteration in organelle dynamics in various pathological system with a hope for specific therapeutic interventions through perturbation of these specific actin filaments along with its associated assembly factors and other actin binding proteins.