Centrosomin and Centrosomes in Cell Division

描述（由申请方提供）：染色体均匀分布到子细胞中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，这可导致细胞死亡或致癌。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，在改变时可能是致癌的。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。为了实现这一点，我们必须了解在中心体发挥作用的蛋白质的作用。我们的主要焦点是中心体蛋白（Cnn），果蝇中心体的主要核心组成部分。Cnn是一种磷蛋白，具有三个假定的亮氨酸拉链，广泛的卷曲螺旋结构域和两个在物种间高度保守的新基序。Cnn是有丝分裂时组装功能性中心体所必需的。在缺乏Cnn的体细胞中，有丝分裂有效地发生，但通过交替的无星体途径。我们推测，有丝分裂的无星路径可能是一个遗迹的进化前体，目前的中心体模式的有丝分裂，发现在大多数动物细胞。本计画的目的是了解细胞分裂过程中细胞神经网路与中心体的功能，以及有丝分裂的无星状体路径。为实现这些目标，制定了三个具体目标。第一个目的是使用体内功能和拯救测定来解剖Cnn蛋白中的功能结构域，通过在果蝇中拯救Cnn来检查潜在的人类同源物，并检查磷酸化在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，然后测定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的细胞中诱导的无星减数分裂样途径。将研究缺乏Cnn（并且具有功能失调的中心体）的细胞中有丝分裂时纺锤体组装和染色体分离的机制。

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.