The role of lipids in mediating the spatiotemporal coordination of cytokinesis in Arabidopsis

脂质在介导拟南芥胞质分裂时空协调中的作用

• 批准号: 505671074
• 负责人: Professorin Dr. Farhah Assaad, Ph.D.
• 金额: --
• 依托单位: INRA, Laboratoire de Reproduction et Development des Plantes
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/505671074?language=en
• 关键词: role; lipids; mediating; spatiotemporal; coordination

In plants, patterning by cell division relies on division plane establishment, on the biogenesis of a membrane compartment called the cell plate, and on cell plate insertion at the division site. It is generally accepted that a landmark is laid down at the plasma membrane before prophase, and that the leading edge of the expanding cell plate is guided towards this cue at the end of cytokinesis. The nature of this positional cue remains elusive and the processes of cell plate guidance and insertion are poorly understood. Lipids are increasingly recognized as important membrane landmarks, but whether specific lipids mark the division site has yet to be investigated. Interestingly, inhibiting the synthesis of phosphoinositides, sterols or very-long chain fatty acids, an essential component of sphingolipids, results in cytokinesis defects. Preliminary data indicate that PI(4,5)P2 phosphoinositides and its phosphatase SAC9 are involved in defining the spatial site of cell plate insertion. PI(4,5)P2 distribution appears to be driven by shomeostatic lipid-lipid interactions. Indeed, we found that the acyl-chain length of sphingolipids is involved in regulating the level of PI(4,5)P2 and that sphingolipids localize at the cell plate. In animals, specific combinations of phosphoinositides and Rab GTPases are responsible for maintaining and co-ordinating intersecting trafficking pathways in the cell. Our preliminary data suggest that in plants, Rab-E GTPases might play a role in cell plate insertion. Furthermore, we propose that Rab-E GTPases are regulated by the TRAPPII tethering complex, a putative Guanine nucleotide Exchange Factor. TRAPPII plays a pivotal role in the spatiotemporal control of plant cytokinesis. In this project, we will address how lipids and key trafficking proteins mediate cell plate insertion by deploying a unique combination of genetic, cell biological and biochemical tools. These include lipid biosensors, lipid click-chemistry, inducible depletion of lipids by optogenetics, super-resolution microscopy, targeted immuno-isolation of membrane complexes and cutting-edge proteomics and lipidomics. Our project is structured around three main work packages, each of which involves all partners. These address the following questions: i) how are lipids sorted at the expanding cell plate or division site? ii) does lipid sorting require a TRAPPII-Rab-E GTPase module? iii) conversely, do lipid landmarks regulate TRAPPII/Rab-E GTPase function? Altogether, our project proposes to gather internationally recognized and unique expertise in cutting-edge plant cell biology and lipid membrane biology and biochemistry. The outcome of this project will break new ground in tackling the question of how plants achieve patterning by cell division, a crucial process for plant growth and development. Additionally, the production of new tools and genetic resources within the frame of this project will be useful for the entire cell biology community.

在植物中，通过细胞分裂形成的模式依赖于分裂平面的建立，依赖于称为细胞板的膜隔室的生物发生，以及依赖于细胞板在分裂位点的插入。通常认为，在前期之前，在质膜上放置了一个界标，并且在胞质分裂结束时，扩展的细胞板的前缘被引导朝向该线索。这种位置线索的性质仍然难以捉摸，细胞板的指导和插入的过程知之甚少。脂质越来越多地被认为是重要的膜标志，但是否特定的脂质标记的分裂网站还有待调查。有趣的是，抑制磷脂酰肌醇、固醇或极长链脂肪酸（鞘脂的重要成分）的合成会导致胞质分裂缺陷。 初步数据表明，PI（4，5）P2磷酸肌醇和它的磷酸酶SAC 9参与定义的空间位置的细胞板插入。PI（4，5）P2分布似乎由稳态脂质-脂质相互作用驱动。事实上，我们发现鞘脂的酰基链长度参与调节PI（4，5）P2的水平，并且鞘脂定位于细胞板。在动物中，磷酸肌醇和Rab GTP酶的特定组合负责维持和协调细胞中交叉的运输途径。我们的初步数据表明，在植物中，Rab-E GTP酶可能在细胞板插入中发挥作用。此外，我们建议，Rab-E GTP酶的TRAPPII拴系复合物，一个假定的鸟嘌呤核苷酸交换因子的调节。TRAPPII在植物胞质分裂的时空调控中起着关键作用。在这个项目中，我们将解决脂质和关键运输蛋白如何通过部署遗传，细胞生物学和生化工具的独特组合来介导细胞板插入。这些包括脂质生物传感器、脂质点击化学、通过光遗传学诱导的脂质耗竭、超分辨率显微镜、膜复合物的靶向免疫分离以及尖端蛋白质组学和脂质组学。我们的项目围绕三个主要工作包展开，每个工作包都涉及所有合作伙伴。这些解决了以下问题：i）脂质如何在扩展的细胞板或分裂位点被分选？ii）脂质分选需要TRAPPII-Rab-E GTPase模块吗？iii）相反，脂质标志物调节TRAPPII/Rab-E GT3功能吗？总而言之，我们的项目旨在收集国际公认的尖端植物细胞生物学和脂质膜生物学和生物化学方面的独特专业知识。该项目的成果将在解决植物如何通过细胞分裂实现图案化的问题上开辟新天地，这是植物生长和发育的关键过程。此外，该项目框架内的新工具和遗传资源的生产将对整个细胞生物学界有用。