Regulation of spindle microtubule organization in plants

细胞生物通过细胞分裂产生新细胞来繁殖。 当真核细胞分裂时，它们产生纺锤体，确保遗传物质忠实地分离成两个子细胞。 这种生物机制是由微管的细胞骨架丝组装而成的。 在真菌和动物等生物体中，孢子体的两极通常由两个中心体定义。 然而，在进化过程中，中心体不再在开花植物中产生。 然而，这些缺乏这种结构的纺锤体仍然可以精确地行使它们在细胞分裂中的基本功能。 本研究旨在了解植物中调控纺锤体微管阵列形成的蛋白质的作用。 从植物纺锤体组装中学到的知识也将阐明其他生物体中细胞分裂的方式。 这项工作将涉及本科生和研究生的参与。 高中生也将有机会在夏季参加研究。 该项目旨在了解机制，调节acentrosomal纺锤体微管组织在植物中采用两个模型系统，基础地钱中的中心体存在，但并不总是用于有丝分裂和开花植物拟南芥缺乏的结构。 对A.拟南芥的研究集中在极光的有丝分裂激酶（alphaAur）及其调节剂TPXL 3、γ-微管蛋白环复合物的微管成核剂（gammaTuRC）以及与纺锤体MT相关的ATK 1和ATK 5的驱动蛋白-14马达。 当这些蛋白质的功能受到损害时，纺锤体不能建立会聚极，最终突变体植物在营养生长和繁殖方面都表现出严重的缺陷。 工作假设是alphaAur调节纺锤体组装中的gammaTuRC和驱动蛋白-14的功能。 具体而言，有丝分裂纺锤体与会聚极的形成需要驱动蛋白-14依赖的微管组织和极向积累的gammaTuRC。 这一假设将通过以下方法进行验证：1）成像技术，以确定有丝分裂期间纺锤体微管组织的基本调节剂的作用; 2）遗传工具，以剖析靶蛋白的功能; 3）生物化学方法，以了解其功能是如何调节的。 这些研究获得的体外和体内结果将有助于阐明调节中心体纺锤体组装的机制。该奖项反映了NSF的法定使命，并且通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Cellular organisms propagate by producing new cells through cell division. When eukaryotic cells divide, they generate the spindle apparatus that ensures the faithful segregation of the genetic material into two daughter cells. This biological machinery is assembled by the cytoskeletal filaments of microtubules. Spindles often have their poles defined by two centrosomes in organisms like fungi and animals. During evolution, however, the centrosome is no longer produced in flowering plants. Yet these spindles lacking this structure can still precisely exercise their essential function in cell division. This research is aimed at understanding the roles of proteins that regulate the formation of the spindle microtubule array in plants. The knowledge learned from spindle assembly in plants also will illuminate how cell division is executed in other organisms. The work will involve the participation of both undergraduate and graduate students. High school students will also have an opportunity to participate in the research during the summers. This project aims to understand mechanisms that regulate acentrosomal spindle microtubule organization in plants by employing two model systems, the basal liverwort Marchantia polymorpha in which the centrosome is present but not always used in mitosis and the flowering plant Arabidopsis thaliana that lacks the structure. Preliminary studies in A. thaliana were focused on the mitotic kinase of Aurora (alphaAur) and its regulator TPXL3, the microtubule nucleator of the gamma-tubulin ring complex (gammaTuRC), and the Kinesin-14 motors of ATK1 and ATK5 that are associated with spindle MTs. When functions of these proteins were compromised, spindles failed to establish convergent poles, and ultimately mutant plants showed severe defects in both vegetative growth and reproduction. The working hypothesis is that alphaAur regulates the functions of gammaTuRC and Kinesin-14 in spindle assembly. Specifically, the formation of mitotic spindles with convergent poles requires Kinesin-14-dependent microtubule organization and poleward accumulation of gammaTuRC. This hypothesis will be tested by employing 1) imaging techniques to determine the actions of essential regulators of spindle microtubule organization during mitosis; 2) genetic tools to dissect functions of targeted proteins; and 3) biochemical methods to learn how their functions are regulated. In vitro and in vivo results garnered from these studies will contribute toelucidating mechanisms that regulate acentrosomal spindle assembly.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.