Molecular Mechanisms of Mitotic Regulation

在细胞分裂过程中，复制基因组的均等分离对于细胞分裂是至关重要的。 所有生物体的发育和繁殖。有丝分裂过程中的错误是 癌细胞的标志和主要化疗药物靶向有丝分裂纺锤体。一 动粒的关键功能是产生纺锤体检查点信号 动粒已经正确地附着在微管上。这个信号是由 将MPS1蛋白定位于Ndc80复合物的钙调蛋白同源结构域， 由极光B调节。然而，Ndc80的这一结构域突出在长的 卷曲螺旋远离极光激酶，使其不清楚如何磷酸化。我们 已经使用了一种大大改进的超分辨率显微镜来观察人类 动粒这种显微镜独特的能力，提供超分辨率的Z平面 对于研究动粒大小的细胞结构至关重要。这种可视化 的Ndc80单分子在未连接的动粒已经确定了一个新的池， 纺锤体中心区Ndc80复合物的MPS1结合区 检查点信号着丝粒。我们假设这个内部池是一个更大的 这是一个比以前认识到的外部池更有效的纺锤体检查点生成器。 我们正在采用超分辨率显微镜来测试这一假设，并进一步 在生成纺锤体检查点时映射关键事件的子动粒位置 信号.我们还将通过何时关闭磁盘轴检查点来确定 动粒附着在微管上。我们正在建立两个重要的新的 关于斯卡情结的发现首先，我们已经确定了启用Ska的步骤 在微管附着后被招募到动粒中。第二，我们已经证明 Ska与PP1结合，提供了一种特异性募集磷酸酶的机制， 正确连接的动粒在这个坚实的基础上，我们将决定 Ndc80，Ska和PP1蛋白如何关闭纺锤体检查点并产生 着丝粒微管附着，允许着丝粒保持结合 解聚微管来移动染色体。

Equal segregation of the replicated genome during cell division is essential for the development and propagation of all living organisms. Errors in mitotic processes are a hallmark of cancer cells and major chemotherapeutics target the mitotic spindle. One critical function of the kinetochore is to generate the spindle checkpoint signal until each kinetochore has properly attached to microtubules. This signal is initiated by the localization of the MPS1 protein to the calponin homology domain of the Ndc80 complex, which is regulated by Aurora B. However, this domain of Ndc80 protrudes on a long coiled coil far from Aurora kinase, making it unclear how it could be phosphorylated. We have employed a vastly improved super-resolution microscope to visualize human kinetochores. This microscopes unique ability to provide super-resolution in the Z-plane is essential for the study of cellular structure the size of a kinetochore. This visualization of single molecules of Ndc80 in unattached kinetochores has identified a novel pool of the MPS1 binding region of the Ndc80 complex in the central region of spindle checkpoint signaling kinetochores. We hypothesize that this internal pool is a more efficient generator of the spindle checkpoint than the previously appreciated outer pools. We are employing super-resolution microscopy to both test this hypothesis and further map the sub-kinetochore location of key events in generating the spindle checkpoint signals. We will also identify how the spindle checkpoint is turned off by when kinetochores attach to microtubules. We are building upon two important new discoveries about the Ska complex. First, we have identified the steps that enable Ska to be recruited to kinetochores after microtubule attachments. Second, we have shown that Ska binds PP1 providing a mechanism to specifically recruit a phosphatase to properly attached kinetochores. Building upon this strong foundation we will determine how the Ndc80, Ska and PP1 proteins turn off the spindle checkpoint and generate the kinetochore microtubule attachment that allows kinetochores to remain bound to depolymerizing microtubules to move chromosomes.