Centrosomin and Centrosomes in Cell Division

描述(申请人提供)：染色体在子代细胞中的平均分布取决于细胞分裂时有丝分裂纺锤体的准确组装。不适当的染色体分离会导致非整倍体，从而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。要做到这一点，我们必须了解在中心体起作用的蛋白质的作用。我们的主要焦点是中心体(CNN)，它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、广泛的螺旋卷曲结构域和两个新的跨物种高度保守的基序的磷蛋白。CNN被要求在有丝分裂时组装功能中心体。在缺乏CNN的体细胞中，有丝分裂有效地发生，但通过另一条反星体途径进行。我们假设，有丝分裂的逆星体途径可能是目前在大多数动物细胞中发现的中心体有丝分裂模式的进化先驱的遗迹。本项目的目的是了解CNN和中心体在细胞分裂中的功能，并确定有丝分裂的逆星体途径。为了实现这些目标，我们设计了三个具体目标。第一个目的是利用体内功能分析和挽救分析来剖析CNN蛋白的功能结构域，通过拯救果蝇中的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利用遗传学和生物化学方法寻找CNN蛋白伙伴，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的细胞中诱导的类反星体减数分裂途径。在缺乏CNN的细胞(和具有功能失调的中心体)的细胞中，纺锤体组装和染色体分离的机制将被研究。

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.