Novel Regulatory Factors of the Spindle Assembly Checkpoint

 描述(申请人提供)：人类细胞分裂是一组高度协调的事件，确保遗传物质(染色体)从一个母细胞适当地传递到两个新形成的细胞。细胞分裂过程中的染色体分离错误会导致非整倍体(一种异常的染色体数目)，这是大多数癌症的一个特征，已被认为是促进肿瘤发生的因素。在中期到后期的转变中，确保姐妹染色单体正确分离的关键是多组分纺锤体组装检查点(SAC)，当感觉到未附着的动粒或非生产性(单调、联会和分节)附着时，SAC被激活，其功能是阻止中期细胞，以便有时间纠正这些缺陷，并在继续细胞分裂之前产生适当的微管-动粒附着。有趣的是，功能性SAC在以下方面发挥作用 像抗分裂药物(抑制有丝分裂的药物)这样的化疗药物会破坏有丝分裂纺锤体，激活SAC，阻止细胞处于中期前期，并引发细胞凋亡。由于了解SAC对于了解肿瘤的发生和肿瘤细胞对抗分裂药物的反应至关重要，它已成为一个吸引人的研究领域。尽管过去40年的研究已经揭示了SAC，但我们远未阐明这一复杂途径所涉及的全部调控因素，也远未了解该途径的错误调控如何导致肿瘤发生和对抗肿瘤药物等化疗药物的耐药性。为了解决这些问题，我们最近对SAC的新型调节因子进行了高通量小干扰RNA(SiRNA)筛选。这种方法产生了两个新的细胞周期蛋白依赖的蛋白激酶(CDK14和CDK15)和两个双特异性磷酸酶(DUSP7和DUSP12)。在紫杉醇等抗有丝分裂药物存在的情况下，这些新因子的失活会导致SAC旁路，紫杉醇通常会激活SAC并诱导细胞死亡。据我们所知，这些因素以前没有与SAC功能联系在一起，总体上限制了遗传和分子特征。因此，了解这些因素是如何调节SAC的，对于理解SAC乃至更广泛的细胞分裂是重要的。我们推测，这些因素通过其磷酸化和去磷酸化活性来控制SAC。因此，我们将通过分析这些函数的功能来检验这一假设 在未受干扰的细胞分裂过程中，以及在产生纺锤体损伤并激活纺锤体组装检查点的抗减数分裂物质存在的情况下，蛋白质。我们期待我们的研究将识别和表征调控SAC的新因素和新途径，我们将能够绘制出它们在时间和空间上的作用，我们对了解细胞分裂机制的贡献将影响未来的癌症研究和癌症患者的生活质量和生存质量。

 DESCRIPTION (provided by applicant): Human cell division is a highly coordinated set of events that ensures the proper transmission of genetic material (chromosomes) from one mother cell to two newly formed cells. Chromosome missegregation during cell division can lead to aneuploidy (an aberrant chromosomal number), which is a hallmark of most cancers and has been proposed to promote tumorigenesis. Critical to ensuring proper sister chromatid separation at the metaphase to anaphase transition is the multi-component spindle assembly checkpoint (SAC), which is activated when unattached kinetochores or nonproductive (monotelic, syntelic, and merotelic) attachments are sensed and functions to arrest cells in metaphase to give time to correct these deficiencies and generate proper microtubule-kinetochore attachments before proceeding with cell division. Interestingly, a functional SAC plays a role in the effectiveness of chemotherapeutic drugs like antimitotics (drugs that inhibit mitosis), which damage the mitotic spindle, activate the SAC, arrest cells in prometaphase and trigger apoptotic cell death. Because understanding the SAC is critical to understanding tumorigenesis and the response of tumor cells to antimitotic drugs, it has become an attractive area of research. Although the last 40 years of research has shed light on the SAC, we are far from elucidating the full complement of regulatory factors involved in this complex pathway and from understanding how misregulation of this pathway can lead to tumorigenesis and resistance to chemotherapeutic drugs like antimitotics. To address these issues, we recently performed a high-throughput small interfering RNA (siRNA) screen for novel regulators of the SAC. This approach yielded two novel cyclin dependent kinases (Cdk14 and Cdk15) and two dual specificity phosphatases (DUSP7 and DUSP12). Inactivation of these novel factors leads to SAC bypass in the presence of antimitotic drugs like Taxol, which normally activate the SAC and induce cell death. To our knowledge, these factors have not been previously linked to SAC functioning and have limited genetic and molecular characterization in general. Thus understanding how these factors regulate the SAC is important to understanding the SAC and more broadly cell division. We hypothesize that these factors are controlling the SAC through their phosphorylation and dephosphorylation activities. Thus, we will test this hypothesis by analyzing the function of these proteins during unperturbed cell divisions and in the presence of antimitotics that generate spindle damage and activate the spindle assembly checkpoint. We expect that our studies will identify and characterize new factors and pathways that regulate the SAC, that we will be able to map their roles in time and space, and that our contributions to understanding the mechanisms of cell division will impact future cancer studies and cancer patient quality of life and survival.