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

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动植物的正常生长和发育至关重要。 这项工作的长期目标是了解植物细胞分裂（胞质分裂）和植物细胞扩增过程中发生的细胞内囊泡运输的分子事件和机制。 在胞质分裂期间，一个或多个胞外分泌途径朝向分裂平面极化-即，分泌囊泡移动到分裂位点--导致称为细胞板的细胞动力学细胞器的重新形成（细胞板是细胞壁的前体结构，其最终将两半分成单独的细胞）。 类似地，植物细胞扩增是通过将携带膜和细胞壁组分的分泌囊泡递送和融合到质膜上的特定位点来介导的，导致新的膜和壁组分嵌入现有的细胞表面，从而导致细胞扩增。 目前，对植物中胞吐和胞吞途径的组织、它们与细胞骨架的相互作用以及参与这些复杂过程的分子机制知之甚少。Bednarek博士最近证明，在模式植物拟南芥中，一种植物特异性蛋白质SCD 1对细胞板形成和极化细胞扩增至关重要。SCD 1是一种130 kDa的外周膜蛋白，含有一个N-末端DENN结构域（以人类DENN蛋白命名，其在氨基酸序列方面与之相似：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，其通常与蛋白质-蛋白质相互作用相关。 尽管DENN结构域的精确功能尚不清楚，但它们已在与Rabs（调节分泌囊泡运输的小GTPases）和其他信号蛋白（包括有丝分裂原活化蛋白激酶）相互作用的动物蛋白质中被鉴定出来。Bednarek博士推测，SCD 1可能在细胞分裂和扩张过程中调节囊泡运输和/或细胞骨架动力学。 该项目旨在：1）研究植物内膜系统中SCD 1的定位和靶向; 2）了解SCD 1相关内膜的身份; 3）鉴定植物极化膜运输所需的SCD 1相互作用蛋白。 该项目将使用整合互补的正向和反向分子遗传学，细胞学和生物化学方法的实验方法。 该项目的成果预计将有助于显着的功能和组织的植物分泌途径及其在细胞板生物发生和极化细胞扩张的作用的理解。该项目完成后，预计将了解SCD 1在植物形态发生中的功能。这些研究也将有助于对其他真核细胞中含DENN结构域的蛋白在膜运输和信号传导中的功能的一般理解。更广泛的影响：该项目将为本科生、研究生和研究生级别的年轻科学家提供现代细胞生物学方面有价值的研究培训。研究生和博士后研究助理也将通过协助本科生课堂教学和监督与资助项目相关的本科生独立研究项目来学习宝贵的教学和指导技能。 该项目产生的所有试剂和研究工具将分发给其他实验室，以协助进一步表征植物生长和发育的膜运输和细胞骨架调节。