Mob1 Localization and Function During Mitosis

Mob1 在有丝分裂期间的定位和功能

• 批准号: 7628920
• 负责人: Charles Bradley Shuster
• 金额: $ 24.25万
• 依托单位: NEW MEXICO STATE UNIVERSITY LAS CRUCES
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-01 至 2013-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7628920
• 关键词: Actins; Adult; Affect; Anaphase; Aneuploidy; Animals; Architecture; Binding Proteins; Biochemical; Cell Cycle; Cell Cycle Arrest; Cell Cycle Checkpoint; Cell Cycle Proteins; Cell Cycle Regulation; Cell Proliferation; Cell division; Cells; Centromere; Chromosome Segregation; Complex; Cytokinesis; Data; Dependence; Development; Drosophila genus; Elements; Ensure; Eukaryota; Event; Family; Fission Yeast; Foundations; Frequencies; Gene Duplication; Gene Family; Genes; Genome; Growth; Homologous Gene; Human; Image; Interphase; Kinetochores; Life; Maintenance; Malignant Neoplasms; Mammalian Cell; Mammals; Mediator of activation protein; Mitosis; Mitotic; Mitotic spindle; Molecular; Molecular Weight; Nuclear; Organ Size; Orthologous Gene; Pathway interactions; Pattern; Phosphorylation; Phosphotransferases; Play; Ploidies; Process; Protein Family; Protein Isoforms; Proteins; RNA Interference; Reporting; Role; Signal Transduction; Sister Chromatid; Small Interfering RNA; TP53 gene; Testing; Tetraploidy; Tissues; Tumor Suppressor Proteins; Yeasts; aurora B kinase; base; constriction; genetic analysis; insight; loss of function; mutant; novel; public health relevance; response; spindle pole body; tumor; tumorigenesis

DESCRIPTION (provided by applicant): Maintenance of chromosomal ploidy during cell division requires a precise coordination of chromosome segregation and cytokinesis such that the contractile ring does not assemble before all replicated sister chromatids are correctly attached to the mitotic spindle and the spindle assembly checkpoint is satisfied. In budding and fission yeast, this process is facilitated by a signaling cascade termed the Mitotic Exit Network/Septation Initiation Network that coordinates mitotic exit and cytokinesis, is based at the spindle pole bodies, and plays an active role in initiating constriction of the actin ring. To date, few functional homologues have been characterized in animal cells, but in the case of the terminal components (Mob1 and Dbf2/Sid2); there have been expansions in both gene families. And while tumor suppressor functions have been ascribed to the mammalian and Drosophila orthologs of Mob1 and Dbf2/Sid2 during G1/S, little is known about how these molecules participate in mitosis and cytokinesis in animal cells. Preliminary studies of Mob1 isoforms in cultured human cells indicate that the localization dynamics mirror that observed in yeast, with Mob1 enriched at the kinetochores and spindle poles early in mitosis, and the spindle midzone and midbody during cytokinesis. Moreover, we have determined that Mob1 and the chromosomal passenger complex are mutually dependent on each other kinetochore localization early in mitosis. Lastly, we identified Large Tumor Supressor 2 (Lats2) as a Mob1A-specific binding protein and possible functional homolog of the Dbf2/Sid2 kinase. Using these preliminary studies as a foundation, this application seeks to combine molecular, biochemical and live cell analyses to test the hypothesis that Mob1 proteins perform roles in regulating in maintaining chromosomal ploidy during both mitosis and interphase. The lines of experimentation that form the Specific Aims will: 1) Determine the molecular determinants of Mob1 localization to the kinetochore; 2) Dissect how Mob1 affects Aurora B function at the kinetochore; and 3) Assess the involvement of Mob1 in the Lats2-p53 response to cytoskeletal disruption. These studies will shed novel insights into a gene family that in animal cells appears to act as a negative regulator of cell proliferation (and whose loss of function is associated with tumor formation), yet is essential for completing cell division in yeast. It is anticipated that these studies will help us reconcile how Mob1 is capable of participating in both of these very different but absolutely critical features of cell cycle regulation. Public Health Relevance: Proper development and maintenance of adult tissues requires that each cell division occurs accurately, and special checkpoints have evolved that act as safeguards for the genome. Mistakes in cell division have a destabilizing effect on growth control, and are believed to be an aggravating factor in tumorigenesis. This proposal seeks to study a highly conserved family of proteins whose functions are well defined in lower eukaryotes, but whose roles remain poorly understood in human cells.

描述（由申请人提供）：细胞分裂过程中染色体倍性的维护需要精确的染色体分离和细胞因子的配位，以便在将所有复制的姐妹染色质正确连接到丝线纺锤体和固定组装检查点之前，收缩环没有组装。在萌芽和裂变酵母中，这一过程由称为有丝分裂出口网络/分隔启动网络的信号级联反应，该网络坐标有丝分裂出口和细胞因子，位于纺锤体上，并在肌动蛋白环的启动中起积极作用。迄今为止，在动物细胞中很少表征功能同源物，但是在末端成分（MOB1和DBF2/SID2）的情况下；两个基因家族都有扩张。尽管在G1/S期间，肿瘤抑制功能已归因于MOB1和DBF2/SID2的哺乳动物和果蝇直系同源物，但对于这些分子如何参与动物细胞中的有丝分裂和细胞因子性，知之甚少。对培养的人类细胞中MOB1同工型的初步研究表明，在酵母中观察到的定位动力学镜面，在有丝分裂的早期，MOB1富集在动力学和纺丝杆上，以及细胞动物期间的纺锤体中区和中型中心。此外，我们已经确定MOB1和染色体乘客复合物在有丝分裂的早期相互依赖于彼此。最后，我们将大型肿瘤supressor 2（LATS2）确定为MOB1A特异性结合蛋白，并且可能是DBF2/SID2激酶的功能同源物。使用这些初步研究作为基础，该应用程序试图结合分子，生化和活细胞分析，以检验以下假设：MOB1蛋白在调节有丝分裂和相间期间在维持染色体拼合方面发挥作用。构成特定目的的实验线将：1）确定MOB1定位到动力学的分子决定因素； 2）剖析MOB1如何影响动力学的Aurora B功能； 3）评估MOB1参与LATS2-P53对细胞骨架破坏的反应。这些研究将对一个基因家族进行新的见解，在动物细胞中似乎是细胞增殖的负调节剂（其功能丧失与肿瘤形成有关），但对于完成酵母的细胞分裂至关重要。预计这些研究将有助于我们调和MOB1如何参与这两种非常不同但绝对关键的细胞周期调节特征。 公共卫生相关性：适当的成人组织的开发和维护要求每个细胞分裂都准确地发生，并且特殊检查点已经进化为对基因组的保障措施。细胞分裂中的错误对生长控制具有不稳定的影响，被认为是肿瘤发生的加重因素。该提议旨在研究一个高度保守的蛋白质家族，其功能在较低的真核生物中得到了很好的定义，但其作用在人类细胞中仍然很糟糕。