Regulation of Cytokinesis by Microtubules in Aspergillus Nidulans

构巢曲霉中微管的细胞分裂调节

• 批准号: 0235364
• 负责人: Bo Liu
• 金额: $ 24万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-04-01 至 2006-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0235364&HistoricalAwards=false
• 关键词: Regulation; Cytokinesis; Microtubules; Aspergillus; Nidulans

Division of one cell into two is one of the key critical functions of life. It is essential that cell division be precisely regulated, both spatially and temporally, in order to ensure appropriate distribution of subcellular components such as organelles and chromosomes to the daughter cells. Cell division is not always necessarily symmetrical; numerous examples of assymetrical division can be found among fungi, plants and animals, and these are often essential for differentiation and organismal morphogenesis. A great deal has been learned about fungal cell division (also termed cytokinesis or septation) from studies of various yeasts and filamentous fungi. In such fungi, septation is regulated by signal transduction pathways such as the septation initiation network (SIN) in fission yeast. SIN includes a MAP- kinase-like kinase cascade, and activation of this cascade initiates septation. The consequence of activation of the SIN network is to activate as-yet-unidentified components at the contractile medial ring, composed mainly of actin microfilaments and myosin plus various other proteins including actin-binding proteins. The ultimate function of this ring is to initiate the assembly of the septum, composed of long chain polysaccharides (beta-glucan and chitin), at the right place. While all SIN molecules localize to the spindle pole body in yeast, the terminal Sid2p kinase and its associated Mob1p partially translocate to the septation site to activate septation. This project addresses the question of how these SIN molecules (Sid2p and Mob1p) travel from the spindle pole body to the septation site. It is proposed that microtubules play essential roles in the localization of SIN molecules. This hypothesis will be tested in the filamentous fungus, Aspergillus nidulans. A. nidulans is a particularly good model organism for these studies because there exists a substantial armamentarium of experimental tools, and completion of the full sequence of its genome is anticipated shortly. In A. nidulans, the AnMOB1 protein localizes not only to the spindle pole body and the septation site, but also to the central spindle. The localization is dependent on microtubules. Cytoplamic dynein, a microtubule motor associated with the spindle during cell division, has been demonstrated to play a role in septum positioning. Dynein mutants will be used to test whether AnMOB1 localization is dependent on cytoplasmic dynein. Experiments will also be performed to test whether spindle pole body localization of AnMOB1 is dependent on minus end-directed kinesin KLPA. The roles of the plus end-directed kinesin BIMC in AnMOB1 localization to the central spindle will be explored. In addition, pharmacological and genetic approaches will be used to test whether microtubule dynamics plays a role in AnMOB1 localization. These studies will provide insights into the roles played by microtubule dynamics, microtubule motors, and the microtubule-organizing center in the intracellular movement of SIN molecules, and ultimately in cytokinesis.Broader Impacts: Aspergillus nidulans is not only a valuable research model, but it is also useful as teaching material for undergraduate and high school students. Dr. Liu uses living Aspergillus to demonstrate cell biological phenomena (cell division, organelle movement, and microtubule dynamics) to local Junior High School students and home-schooled students who visit his laboratory. He also uses Aspergillus as a teaching model in an undergraduate Introductory Biology course and in a graduate level course, Common Approaches in Plant Cell and Molecular Biology. Dr. Liu has also mentored several undergraduates who have performed research in his laboratory; these students have gone on to graduate school or to careers in biotechnology research.

将一个细胞分裂成两个细胞是生命的关键功能之一。 细胞分裂必须在空间和时间上精确调节，以确保亚细胞组分（如细胞器和染色体）向子细胞的适当分布。 细胞分裂不一定总是对称的;在真菌、植物和动物中可以找到许多不对称分裂的例子，这些对于分化和生物体形态发生通常是必不可少的。 通过对各种酵母和丝状真菌的研究，人们对真菌细胞分裂（也称为胞质分裂或分隔）有了大量的了解。 在这些真菌中，分隔是由信号转导途径如分裂酵母中的分隔起始网络（SIN）调节的。 SIN包括MAP-激酶样激酶级联，并且该级联的激活启动分隔。SIN网络激活的结果是激活收缩内侧环上尚未识别的成分，主要由肌动蛋白微丝和肌球蛋白以及包括肌动蛋白结合蛋白在内的各种其他蛋白质组成。 这个环的最终功能是启动隔膜的组装，隔膜由长链多糖（β-葡聚糖和几丁质）组成，在正确的位置。 虽然所有SIN分子定位于纺锤体极体在酵母中，终端Sid 2 p激酶和其相关的Mob 1 p部分易位到分隔位点激活分隔。 该项目解决了这些SIN分子（Sid 2 p和Mob 1 p）如何从纺锤体极体到分隔位点的问题。 这表明，微管在SIN分子的定位中起着重要的作用。 这一假设将在丝状真菌构巢曲霉中进行测试。 A.对于这些研究来说，巢状生物是一种特别好的模式生物，因为存在大量的实验工具，并且预期不久将完成其基因组的全序列。 以. AnMOB 1蛋白不仅定位于纺锤体极体和分隔部位，而且定位于中央纺锤体。定位依赖于微管。细胞质动力蛋白是细胞分裂过程中与纺锤体相关的微管马达，已被证明在细胞间隔定位中发挥作用。 动力蛋白突变体将用于测试AnMOB 1定位是否依赖于细胞质动力蛋白。还将进行实验以测试AnMOB 1的纺锤体极体定位是否依赖于负末端定向驱动蛋白KLPA。正末端定向驱动蛋白BIMC在AnMOB 1定位到中央纺锤体中的作用将被探索。此外，药理学和遗传学的方法将被用来测试是否微管动力学在AnMOB 1定位中发挥作用。 这些研究将深入了解微管动力学、微管马达和微管组织中心在SIN分子的细胞内运动中以及最终在胞质分裂中所发挥的作用。更广泛的影响：构巢曲霉不仅是一个有价值的研究模型，而且它也是有用的作为本科生和高中生的教材。刘博士利用活曲霉菌向参观他的实验室的当地初中生和在家上学的学生演示细胞生物学现象（细胞分裂，细胞器运动和微管动力学）。 他还将曲霉菌作为本科生物学导论课程和研究生课程《植物细胞和分子生物学常用方法》的教学模型。 刘博士还指导了几位在他的实验室进行研究的本科生;这些学生已经进入研究生院或从事生物技术研究。