Mechanisms of how nuclear envelope bridges link nuclei to the cytoskeleton.

核膜桥如何将细胞核与细胞骨架连接起来的机制。

• 批准号: 8467891
• 负责人: DANIEL A STARR
• 金额: $ 15.5万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-01-01 至 2015-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8467891
• 关键词: Active Biological Transport; Ataxia; Binding; Bypass; Caenorhabditis elegans; Cell Nucleus; Cell Polarity; Cell division; Cell physiology; Cells; Chromosomes; Coupled; Cytoplasm; Cytoskeleton; Data; Defect; Developmental Cell Biology; Developmental Process; Diffuse; Disease; Docking; Dynein ATPase; Elements; Embryo; Event; Fertilization; Figs - dietary; Film; Fostering; Goals; Golgi Apparatus; Health; Human; Importins; Kinesin; Link; Location; Malignant Neoplasms; Mediating; Membrane; Membrane Protein Traffic; Membrane Proteins; Microtubules; Mining; Mission; Modeling; Molecular; Molecular Genetics; Motor; Movement; Muscular Dystrophies; Mutation; Nuclear; Nuclear Envelope; Nuclear Import; Nuclear Inner Membrane; Nuclear Lamina; Nuclear Outer Membrane; Nuclear Pore; Organelles; Peripheral; Positioning Attribute; Process; Progeria; Proteins; Public Health; Recruitment Activity; Regulation; Research; Role; Signal Transduction; Site; Structural Protein; Surface; Testing; Transducers; War; Work; cell motility; human disease; innovation; lissencephaly; membrane biogenesis; migration; neuromuscular; novel; polarized cell; protein protein interaction; protein transport; trafficking

DESCRIPTION (provided by applicant: A wide variety of cellular processes, including fertilization, cell division, cell migration, and cell polarity, depend on nuclear migration events. Inner nuclear membrane SUN proteins and outer nuclear membrane KASH proteins couple nuclei to the cytoskeleton. Gaps remain in understanding how KASH-SUN bridges are formed and function. Specifically, the molecular mechanisms of how proteins are trafficked to the inner nuclear mem- brane, how microtubules and motors are coordinated to move nuclei, and how KASH and SUN proteins interact to connect cytoplasmic forces to nuclei remain unknown. Our hypothesis is that forces generated by microtubule motors in the cytoplasm are connected to the nucleus by a bridge of conserved KASH and SUN proteins. Understanding how forces are transferred across the nuclear envelope will allow us to elucidate mechanisms of how nuclei are positioned in a cell, how chromosomes are moved inside the nucleus, and how perturbations of these processes disrupt cell and developmental processes. Our model will be tested by three specific aims: (Aim 1) Elucidate mechanisms of inner nuclear membrane biogenesis. The current paradigm is that membrane proteins diffuse within the ER membrane to the nuclear envelope. Our preliminary data support an alternative active transport model for inner nuclear membrane trafficking, using a combination of the soluble nuclear import machinery, membrane-bound importins, and a Golgi trafficking intermediate. We hypothesize that multiple inner-nuclear-membrane-localization signals function to first actively transport UNC-84 from the peripheral ER to the nuclear envelope and to then mediate movement across the nuclear pore. (Aim 2) Deter- mine how kinesin, dynein, and microtubules function to move nuclei. Tug-of-war, interdependent regulation, and bi-directional movement are proposed models to explain how motors of opposite polarity function together to move a cargo. Our hypothesis is that kinesin-1 provides the force to move nuclei and that dynein mediates backwards movements and rolling to bypass roadblocks. We will distinguish between two models for how NOCA-1 regulates polarized microtubule arrays-by regulating either plus-end tip dynamics or nucleation of microtubules. (Aim 3) Determine how forces generated in the cytoplasm are coupled to the nucleus. Two models could explain the role of the KASH-SUN bridge in nuclear migration; they could serve simply as outer nuclear docking sites or, also as transducers of force across the nuclear envelope. We hypothesize that forces generated in the cytoplasm are directly linked to the nuclear lamina by KASH-SUN bridges. Our approach is innovative because it takes advantage of a C. elegans model with unique genetic and molecular strengths with the ability to film and quantify nuclear migration. The proposed research is significant because it is expected to (A) elucidate mechanisms of protein transport to the inner nuclear membrane, (B) elucidate mechanisms of bi- directional nuclear migration along polarized microtubules that will be applicable to other large cargos, and (C) determine how the forces that move nuclei are transferred across the nuclear envelope.

DESCRIPTION (provided by applicant: A wide variety of cellular processes, including fertilization, cell division, cell migration, and cell polarity, depend on nuclear migration events. Inner nuclear membrane SUN proteins and outer nuclear membrane KASH proteins couple nuclei to the cytoskeleton. Gaps remain in understanding how KASH-SUN bridges are formed and function. Specifically, the molecular mechanisms of how proteins are trafficked to the inner nuclear mem- Brane，微管和电动机如何配位以移动核，而Kash和Sun蛋白如何相互作用，将细胞质力与细胞核相互作用，我们的假设是由微管在细胞质中产生的力，使细胞质中的微动物与核的桥梁相连。细胞核位于细胞中，染色体如何在细胞核内移动，以及这些过程的扰动如何破坏细胞和发育过程。我们的模型将通过三个特定目的测试：（目标1）阐明内部核膜生物发生的机制。当前的范式是膜蛋白在ER膜内扩散到核包膜。我们的初步数据使用可溶性核进口机制，膜结合的进口蛋白和高尔基运输中间体的组合，支持内部核膜运输的替代主动运输模型。我们假设多个内部核对解信号信号的功能首先将UNC-84从外围ER运输到核络壳，然后介导跨核孔的运动。 （AIM 2）确定驱动蛋白，动力蛋白和微管如何发挥核。提出了拔河，相互依存的调节和双向运动的拟议模型，以解释相反极性功能的电动机如何一起移动货物。我们的假设是，驱动蛋白1提供了移动核的力，并且动力蛋白介导了向后运动并滚动以绕过障碍。我们将区分两个模型，用于通过调节高端尖端动力学或微管的成核调节极化微管阵列。 （AIM 3）确定细胞质中产生的力如何与细胞核耦合。两个模型可以解释Kash-Sun桥在核迁移中的作用。它们可以简单地用作外部核对接部位，也可以作为跨核包膜的力传感器。我们假设在细胞质中产生的力与Kash-Sun桥直接与核层息息相关。我们的方法具有创新性，因为它利用了具有独特的遗传和分子强度的秀丽隐杆线虫模型，具有拍摄和量化核迁移的能力。拟议的研究之所以重要，是因为（a）阐明蛋白质转运到内部核膜的机制，（b）阐明沿极化微管的双向核迁移的机制，这些机制将适用于其他大型碳，以及（c）如何确定核能转移到核心跨核内的核能转移。