Characterization of Novel Importin-Beta Targets in Mitotic Spindle Assembly

微管的成核和组织在时间和空间上的控制对一些基本的细胞过程是必不可少的，包括细胞形状的改变、细胞内的运输、细胞的运动、胚胎发育期间的细胞质分裂和细胞分裂过程中的染色体分离。大多数真核细胞包含一个复杂的大分子机器，即有丝分裂纺锤体，它确保在细胞分裂期间将一套完整的染色体分配给每个亚细胞。有丝分裂纺锤体组装是一个高度协调的过程，受到严格的调控，以避免错误的染色体分离，这些错误可能导致发育缺陷、细胞死亡或基因组不稳定。利用非洲爪哇的模型系统，PI已经确定Importin-b和相互作用的蛋白Maskin是调节有丝分裂纺锤体组装的关键蛋白。这一新项目继续了PI关于Importin-b和Maskin如何调控有丝分裂纺锤体组装的分子机制的研究。将解决的具体问题包括：改变Maskin的水平对主轴装配有什么影响？马斯金互动搭档(S)是什么？Maskin对体外培养的微管有何作用？Maskin在纺锤体组装中的作用与其在翻译调控中的作用之间是否存在联系？Maskin是如何受到监管的？Importin-b在Maskin的调节中起什么作用？这个项目的结果将进一步了解Maskin和其他有丝分裂纺锤体组装因子在非洲爪哇早期发育过程中微管组装和组织的时空调节中的作用，这也可能为该蛋白家族的其他成员的功能提供线索。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Maskin和/或它们的人类同系物在细胞或生物体的生活中所扮演的更广泛的角色提供新的见解。该项目将提供三个层次的研究培训：本科生、研究生和博士后。

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.