Role of SCD1 in Plant Cytokinesis and Polarized Cell Expansion

SCD1 在植物细胞分裂和极化细胞扩增中的作用

• 批准号: 0446157
• 负责人: Sebastian Bednarek
• 金额: $ 44.65万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-15 至 2009-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0446157&HistoricalAwards=false
• 关键词: Role; SCD1; Plant; Cytokinesis; Polarized; Role; SCD1; Plant; Cytokinesis; Polarized

Cell growth and division are crucial for normal growth and development of multicellular plants and animals. The long-term objective of this work is to understand the molecular events and mechanisms involved in intracellular vesicle trafficking that take place during plant cell division (cytokinesis) and plant cell expansion. During cytokinesis, one or more exocytic secretory pathways are polarized toward the plane of division - i.e., secretory vesicles move to the division site -- resulting in the de novo formation of the cytokinetic organelle known as the cell plate (a structure that is the precursor to the cell wall that will eventually divide the two halves into separate cells). Similarly, plant cell expansion is mediated through the delivery and fusion of secretory vesicles carrying membrane and cell wall components to specific sites on the plasma membrane, resulting in intercalation of new membrane and wall components to the existing cell surface and thereby cell expansion. At the present time, relatively little is known about the organization of the exocytic and endocytic pathways, their interaction with the cytoskeleton, and the molecular machinery involved in these complex processes in plants. Dr. Bednarek has recently demonstrated that, in the model plant Arabidopsis thaliana, a plant-specific protein, SCD1, is critical for cell plate formation and polarized cell expansion. SCD1 is a 130 kDa peripheral membrane protein containing an N-terminal DENN domain (named for the human DENN protein which it resembles in terms of amino acid sequence: Differentially Expressed in Normal and Neoplastic cells) and eight C-terminal WD-40 repeats, which are commonly associated with protein-protein interactions. Although the precise function of DENN domains is not known, they have been identified in animal proteins that interact with Rabs (small GTPases that regulate secretory vesicle trafficking) and other signaling proteins including mitogen-activated protein kinases. Dr. Bednarek hypothesizes that SCD1 may regulate vesicle trafficking and/or cytoskeletal dynamics during cell division and expansion. This project has been designed to: 1) study the localization and targeting of SCD1 within the plant endomembrane system; 2) learn the identity of SCD1-associated endomembranes; and 3) identify SCD1-interacting proteins required for polarized membrane trafficking in plants. The project will use experimental approaches that integrate complementary forward and reverse molecular genetic, cytological, and biochemical approaches. The outcome of this project is expected to contribute significantly to both an understanding of the function and organization of the plant secretory pathway and its role in cell plate biogenesis and polarized cell expansion. Upon completion of the project, it is expected that the function of SCD1 in plant morphogenesis will be understood. These studies will also contribute to a general understanding of the function of DENN-domain containing proteins in membrane trafficking and signaling in other eukaryotic cells. Broader Impact: This project will provide valuable research training in modern cell biology for young scientists at the undergraduate, graduate and postgraduate level. Graduate students and postdoctoral research associates will also learn valuable teaching and mentoring skills by assisting undergraduate classroom instruction and by supervising undergraduate independent study projects related to the funded project. All reagents and research tools generated by this project will be distributed to other laboratories to assist in the further characterization of membrane trafficking and cytoskeletal regulation of plant growth and development.

细胞生长和分裂对于多细胞植物和动物的正常生长和发展至关重要。 这项工作的长期目标是了解在植物细胞分裂（细胞因子）和植物细胞扩张期间发生的细胞内囊泡运输的分子事件和机制。 在细胞因子过程中，一种或多种胞外分泌途径向分裂平面（即分泌囊泡移动到分裂位点）的两极分化，从而导致细胞动力学细胞器的从头形成被称为细胞板（一种被称为细胞板的结构，是最终将两层分为单独细胞分为单独细胞的细胞壁的结构）。 同样，通过将膜和细胞壁成分的分泌囊泡的输送和融合到质膜上的特定位点，从而导致新膜和壁成分与现有细胞表面的插入，从而介导植物细胞的扩张。 目前，关于胞外和内吞途径的组织，与细胞骨架的相互作用以及植物中这些复杂过程所涉及的分子机械的相互作用相对较少。 Bednarek博士最近证明，在模型植物拟南芥中，植物特异性蛋白SCD1对于细胞板形成和极化细胞膨胀至关重要。 SCD1是一个130 kDa的外围膜蛋白，其中含有N端DENN结构域（以人类DENN蛋白的名字命名，其与氨基酸序列相似：在正常和肿瘤细胞中差异表达）和八个C-末端WD-40重复序列，通常与蛋白质蛋白质相互作用相关。 尽管尚不清楚DENN结构域的确切功能，但它们已在与RABS相互作用的动物蛋白（调节分泌囊泡运输的小GTPase）和其他信号蛋白（包括有丝分裂原激活蛋白激酶）相互作用的动物蛋白中鉴定出来。 Bednarek博士假设SCD1可以调节细胞分裂和扩张期间的囊泡运输和/或细胞骨架动力学。 该项目旨在：1）研究植物膜系统中SCD1的定位和靶向； 2）学习与SCD1相关的恩子膜的身份； 3）确定植物中极化膜运输所需的SCD1相互作用蛋白。 该项目将采用实验方法，以整合互补的前向和反向分子遗传，细胞学和生化方法。 预计该项目的结果将对植物分泌途径的功能和组织的理解及其在细胞板生物发生和极化细胞膨胀中的作用产生重大贡献。项目完成后，预计将了解SCD1在植物形态发生中的功能。这些研究还将有助于对其他真核细胞中含有蛋白质的蛋白质的功能进行普遍了解。更广泛的影响：该项目将为本科，研究生和研究生水平的年轻科学家提供现代细胞生物学的宝贵研究培训。研究生和博士后研究伙伴还将通过协助本科课堂教学和监督与资助项目相关的本科独立研究项目来学习宝贵的教学和指导技能。 该项目生成的所有试剂和研究工具都将分配给其他实验室，以帮助进一步表征膜贩运和植物生长和开发的细胞骨架调节。