Centrosomin and Centrosomes in Cell Division

描述（由申请人提供）：染色体在子细胞中的均匀分布取决于细胞分裂时有丝分裂纺锤体的准确组装。染色体的不适当分离导致非整倍体，这可能导致细胞死亡或癌变。控制细胞骨架的蛋白质，包括那些调节微管动力学和纺锤体组装的蛋白质，在改变时可能致癌。我们的目标是了解中心体在细胞骨架组织和其他细胞过程中的功能。要做到这一点，我们必须了解在中心体中起作用的蛋白质的作用。我们主要关注的是中心体蛋白（Cnn），这是果蝇中心体的主要核心成分。Cnn是一种具有三个假定的亮氨酸拉链，广泛的卷曲线圈结构域和两个跨物种高度保守的新基序的磷蛋白。有丝分裂时需要Cnn来组装功能性中心体。在缺乏Cnn的体细胞中，有丝分裂有效地发生，但通过另一种方式发生。我们假设，有丝分裂的非星体途径可能是在大多数动物细胞中发现的当前中心体有丝分裂模式的进化前体的遗迹。本课题旨在了解Cnn和中心体在细胞分裂中的作用，明确有丝分裂的胞外通路。为实现这些目标，制定了三个具体目标。第一个目的是利用体内功能和拯救实验解剖Cnn蛋白的功能域，通过拯救果蝇的Cnn来检测潜在的人类同源物，并研究磷酸化在Cnn功能中的作用。我们的第二个目标是使用遗传和生化方法鉴定Cnn蛋白伴侣，然后分析它们在细胞中的定位，它们在中心体功能中的作用，以及它们在Cnn中心体定位中的作用。我们的第三个目标是确定在缺乏Cnn的细胞中诱导的鼻窦减数分裂样途径。在缺乏Cnn的细胞（和功能失调的中心体）中，纺锤体组装和染色体分离在有丝分裂中的机制将被研究。

DESCRIPTION (provided by applicant): The equal distribution of chromosomes into daughter cells depends upon the accurate assembly of the mitotic spindle at cell division. The inappropriate segregation of chromosomes leads to aneuploidy, which can result in cell death or carcinogenesis. Proteins that control the cytoskeleton, including those that regulate microtubule dynamics and spindle assembly, can be oncogenic when altered. Our goal is to understand the function of the centrosome in cytoskeletal organization and other cellular processes. To achieve this, we must understand the roles of proteins that function at the centrosome. Our main focus is on Centrosomin (Cnn), a major core component of centrosomes in Drosophila. Cnn is a phosphoprotein with three putative leucine zippers, extensive coiled-coil domains, and two novel motifs that are highly conserved across species. Cnn is required to assemble functional centrosomes at mitosis. In somatic cells that lack Cnn, mitosis occurs efficiently, but by an alternate, anastral pathway. We hypothesize that the anastral pathway for mitosis may be a vestige of an evolutionary precursor to the current centrosomal mode of mitosis that is found in most animal cells. The purpose of this project is to understand the functions of Cnn and centrosomes in cell division, and to define the anastral pathway for mitosis. Three specific aims are designed to accomplish these goals. The first aim is to dissect the functional domains in Cnn protein using in vivo functional and rescue assays, to examine potential human homologs by rescue of Cnn in Drosophila, and to examine the role of phosphorylation in Cnn function. Our second aim is to identify Cnn protein partners using genetic and biochemical approaches, then assay their localization in the cell, their role in centrosome function, and their role in centrosomal localization of Cnn. Our third aim is to define the anastral meiosis-like pathway that is induced in cells that lack Cnn. The mechanisms for spindle assembly and chromosome segregation at mitosis in cells that lack Cnn (and have dysfunctional centrosomes) will be investigated.