Defining the regulatory role of mitotic cyclins on Endoplasmic Reticulum reorgani

描述（由申请人提供）：主要的细胞功能，如蛋白质合成和折叠，脂质合成，细胞内钙储存和大分子的核运输都依赖于内质网（ER）。内质网结构或功能的缺陷与许多慢性疾病，如2型糖尿病和自闭症，以及遗传性痉挛性截瘫（HSP）和阿尔茨海默病等神经退行性疾病有关。在有丝分裂过程中，内质网形态发生了巨大的变化，这是正常的膜分配和核膜形成所必需的现象。对于有丝分裂ER的变化是如何发生的，它们是如何被调节的，或者是哪些分子机制导致了这些变化，我们所知相对较少。有丝分裂周期蛋白：Cdk激酶复合物是细胞分裂过程中核和细胞骨架动力学的主要调节因子，但它们在有丝分裂ER重组中的作用尚不清楚。此外，由于小gtpase的Ras超家族成员控制有丝分裂过程中的变化，它们可能驱动有丝分裂ER动力学。事实上，最近发现Rab5 GTPase在有丝分裂ER结构中具有独立于其内吞作用的作用。因此，探索这些蛋白如何影响内质网形态是一个需要解决的关键问题。本项目的目标是确定有丝分裂周期蛋白Cdk对有丝分裂过程中内质网重组的调控，并确定一种协调有丝分裂内质网重组与Rab5 GTPase活性的分子途径。这些过程将在模式生物——黑腹果蝇的胚胎中详细研究。早期果蝇胚胎是研究有丝分裂的理想胚胎，因为它的细胞周期快速而缩短，每15分钟发生一次有丝分裂。具体来说，细胞周期进程或Rab5活性将通过既定的方法进行调节，并通过gfp标记的ER标记物的延时共聚焦成像来评估它们对ER形态学的影响。本研究的目的如下：(1)确定有丝分裂周期蛋白在果蝇早期胚胎有丝分裂ER重组中的作用。(2)研究Rab5活性调控对有丝分裂ER重组的影响。

DESCRIPTION (provided by applicant): Major cellular functions such as protein synthesis and folding, lipid synthesis, intracellular calcium storage, and nuclear transport of macromolecules all depend on the endoplasmic reticulum (ER). Failures in ER structure or function have been linked to a host of chronic diseases such as type-2 diabetes and autism, and neurodegenerative diseases such as hereditary spastic paraplegia (HSP) and Alzheimer's disease. During mitosis, ER morphology changes dramatically, a phenomenon necessary for proper membrane partitioning and nuclear membrane formation. Relatively little is known about how mitotic ER changes occur and how they are regulated, or which molecular mechanisms are responsible for these changes. Mitotic cyclin:Cdk kinase complexes are master regulators of nuclear and cytoskeletal dynamics during cell division, yet their involvement in mitotic ER reorganization is unknown. Additionally, since members of the Ras superfamily of small GTPases control changes during mitosis, they are likely to drive mitotic ER dynamics. Indeed, the Rab5 GTPase was recently found to have a role in mitotic ER structure independent of its endocytic role. Therefore, exploring how these proteins affect ER morphology is a key issue to be addressed. The goal of this project is to define the regulation of ER reorganization during mitosis by mitotic cyclin:Cdk and to define a molecular pathway that coordinates mitotic ER reorganization with Rab5 GTPase activity. These processes will be studied in detail in the embryo of the model organism, Drosophila melanogaster. The early Drosophila embryo is ideal for studying mitosis due to its rapid, abbreviated cell cycle, with initial rounds of mitosis occurring every ~15 minutes. Specifically, cell cycle progression or Rab5 activity will be modulated through established methods, and their effects on ER morphology assessed via timelapse confocal imaging of GFP-tagged ER markers. The aims of the proposal are as follows: (1) Determine the role of mitotic cyclins on mitotic ER reorganization in the early Drosophila embryo. (2) Investigate how modulation of Rab5 activity affects mitotic ER reorganization. PUBLIC HEALTH RELEVANCE: This proposal has broad and significant relevance to major chronic human diseases like type-2 diabetes, autism, and Alzheimer's disease, due to the fundamental roles of the ER in cellular function. Completion of the proposed experiments would yield a basic molecular understanding of how ER morphology is regulated during the cell cycle. This particular knowledge would contribute to the development of therapies for diseases like hereditary spastic paraplegia.