Characterization of Novel Importin-Beta Targets in Mitotic Spindle Assembly

微管成核和组织的时空控制对几个基本的细胞过程至关重要，包括细胞形状变化、细胞内运输、细胞运动、胚胎发育期间的细胞质分配和细胞分裂期间的染色体分离。大多数真核细胞都含有一个复杂的大分子机器，即有丝分裂纺锤体，它确保在细胞分裂过程中，一套完整的染色体被分配到每个亚细胞。有丝分裂纺锤体组装是一个高度协调的过程，受到严格调节，以避免染色体分离错误，可能导致发育缺陷，细胞死亡或基因组不稳定。利用Xenopus模型系统，PI已经鉴定出importin-b和一种相互作用的蛋白mask是调控有丝分裂纺锤体组装的关键蛋白。这个新项目继续PI的研究，了解如何进口蛋白b和掩膜调节有丝分裂纺锤体组装的分子机制。将解决的具体问题包括：改变屏蔽层的水平对主轴装配的影响是什么？什么是口罩交互伙伴？面膜在体外对微管有什么影响？掩膜蛋白在纺锤体组装中的作用与其在转译调控中的作用之间是否存在联系？如何规管口罩？importin-b对口罩的调节作用是什么？本项目的研究结果将进一步了解掩膜和其他有丝分裂纺锤体组装因子在爪蟾早期发育过程中微管组装和组织的时空调控中的作用，这也可能揭示该蛋白家族其他成员的功能。这些结果还将进一步了解importin-b如何调节纺锤体组装，并将为importin-b和mask和/或它们的人类同源物在细胞或生物体的生命中更普遍地发挥作用提供新的见解。该项目将提供本科生、研究生和博士后三个层次的研究培训。

Temporal and spatial control of microtubule nucleation and organization are essential for several fundamental cellular processes, including cellular shape changes, intracellular transport, cell motility, cytoplasmic partitioning during embryonic development, and the separation of chromosomes during cell division. Most eukaryotic cells contain an elaborate macromolecular machine, the mitotic spindle, which ensures that a complete set of chromosomes is distributed to each subcell during cell division. Mitotic spindle assembly is a highly orchestrated process that is tightly regulated to avoid mistakes in chromosome segregation that could lead to developmental defects, cell death, or genomic instability. Using the Xenopus model system, the PI has identified importin-b and an interacting protein, maskin, as key proteins in the regulation of mitotic spindle assembly. This new project continues the PI's research on understanding the molecular mechanism of how importin-b and maskin regulate mitotic spindle assembly. The specific questions that will be addressed include: What is the effect on spindle assembly of altering the levels of maskin? What are the maskin interacting partner(s)? What is the effect of maskin on microtubules in vitro? Is there a link between maskin's role in spindle assembly and its role in translational regulation? How is maskin regulated? What is the role of importin-b in the regulation of maskin? Results from this project will further the understanding of the role of maskin and other mitotic spindle assembly factors in the spatial and temporal regulation of microtubule assembly and organization during early development in Xenopus, which may also shed light on the function of other members of this family of proteins. The results will also further the understanding of how importin-b regulates spindle assembly and will provide new insights into the role that importin-b and maskin and/or their human homologs play more generally in the life of a cell or an organism. The project will provide research training at three levels: undergraduate, graduate and postdoctoral.