Defining the role of EDE1 a novel microtubule-located protein required for nuclear division in Arabidopsis

在许多植物中，种子的胚乳是通过一系列快速的核分裂形成的，这些分裂导致一个包含数百个细胞核的非常大的细胞的发育，称为空心细胞或合胞体。细胞壁随后在细胞核之间形成，之后，淀粉和蛋白质（人类在食物中使用的）被合成。重复有丝分裂显然对胚乳的发育非常重要，但到目前为止，我们还不清楚这一过程是如何控制的。我们最近发现了一个新的拟南芥突变体，其胚乳合胞核在DNA复制后不能正确分离，我们称之为胚乳缺陷1 （ede1）。在这个新的突变体中，胚胎的发育不受影响。这表明该基因在胚乳中对控制细胞周期（即细胞核是否继续分裂）很重要。我们从野生型拟南芥中克隆了EDE1基因，并表明它在活细胞中与微管相互作用，微管是帮助细胞分裂的支架结构。EDE1基因在拟南芥中有7个近亲，这些近亲中至少有一些可能在控制植物细胞周期中发挥相关作用。已经发现EDE1基因在植物其他正在经历快速细胞分裂的部位（如茎的生长尖端）也被打开，这表明它可能参与控制胚乳以外组织的细胞周期。当EDE1蛋白与荧光报告蛋白融合并在拟南芥细胞培养物中表达时，发现该蛋白与有丝分裂纺锤体相关，这是两组染色体分离的微管结构，进一步证明它参与核分裂。本项目旨在研究EDE1基因及其相关基因在控制细胞周期中的功能。我们将研究ede1突变体如何改变细胞周期，以及ede1蛋白在细胞分裂过程中如何与有丝分裂纺锤体相互作用。我们将确定与EDE1蛋白相互作用的蛋白质，以便我们能够清楚地了解其在细胞中的功能。我们还将鉴定相关基因发生突变的植物，并研究这些植物的细胞周期，帮助我们确定这些基因是否也在控制细胞周期中具有相关功能。

In many plants, the endosperm of the seed forms by a series of rapid nuclear divisions that lead to the development of one very large cell containing hundreds of nuclei known as a coenocyte or syncitium. Cell walls subsequently develop between the nuclei and after that, starch and proteins (which humans use in food) are synthesised. The repeated mitosis is clearly very important to the development of the endosperm but as yet, we do not understand how the process is controlled. We have recently identified a new mutant of Arabidopsis in which the nuclei of the endosperm syncitium are greatly enlarged and do not separate correctly after DNA replication and we have called it endosperm defective 1 (ede1). In this new mutant, the development of the embryo is unaffected. This suggests the gene is important in the endosperm for controlling the cell cycle ¿ that is, whether the nuclei keep dividing or not. We have cloned the EDE1 gene from wild type Arabidopsis and shown that it interacts in living cells with microtubules, which are the scaffolding structures that help the cell divide. The EDE1 gene has seven close relatives in Arabidopsis and it is likely that at least some of these relatives play related roles in controlling the cell cycle in plants. The EDE1 gene has been found to be switched on in other parts of the plant that are undergoing rapid cell division such as the growing tip of the stem, indicating that it is likely to be involved in controlling the cell cycle in tissues other than the endosperm. When EDE1 protein is fused to a fluorescent reporter protein and expressed in cell cultures from Arabidopsis, the protein is found to associate with the mitotic spindle, which is the microtubular structure on which the two sets of chromosomes are separated, giving further evidence that it is involved in nuclear division. The aim of this project is to investigate the function of the EDE1 gene and its relatives in controlling the cell cycle. We will investigate how the cell cycle is altered in the ede1 mutant and how the EDE1 protein interacts with the mitotic spindle during cell division. We will identify proteins that interact with the EDE1 protein so that we can develop a clear picture of its function in the cell. We will also identify plants that have been mutated in the related genes and study the cell cycle in those plants, helping us to determine whether those genes also have related functions in controlling the cell cycle.