Regulation of mitotic chromosomes

项目摘要 有丝分裂过程中染色体的正确分离是细胞生长和生物体发育的基础。 这一步的失败会导致发育性疾病、免疫缺陷和癌症。我的研究项目 旨在揭示染色体分离的关键分子机制，并阐明 他们的失败，这可以用来提高化疗治疗的疗效。 1)核小体调节因子在染色体分离中的作用：在有丝分裂过程中， 改变它们的功能和形态以支持它们的分离。染色体变得浓缩， 促进有丝分裂装置的形成，如动粒和纺锤体微管。虽然组蛋白 是最丰富的染色质蛋白，组蛋白在转录调控中的重要性使其 很难剖析它们在有丝分裂中的直接作用。我们的实验室已经建立了一种新的方法， 组蛋白，并评估其后果使用爪蟾卵提取物，其中概括了各种 染色质事件独立于转录。我们发现染色体乘客复合体 (CPC)必须与核小体和微管相互作用以支持纺锤体组装。如染色质 在CPC调控的蛋白质中，我们发现了一种新的由HELLS组成的核小体重塑复合物， CDCA 7与着丝粒不稳定和面部畸形（ICF）综合征有关。通过剖析角色 HELLS-CDCA 7和其他核小体调节因子，我们将研究知之甚少的机制 和核小体动力学和功能的有丝分裂特异性控制的功能意义。 2)维持人类着丝粒完整性的机制：人类着丝粒，着丝粒组装的地方 用来捕获微管的DNA是由一长串重复元件α-卫星DNA组成的。我们已经表明 α-卫星重复排列在癌细胞中和细胞衰老期间变得不稳定， 着丝粒结合蛋白对保持这种排列很重要。我们将剖析 保持着丝粒相关重复元件的完整性。 3)先天免疫系统对有丝分裂失败的识别：我们假设核小体作为一种免疫系统， 区分基因组DNA和外来或异常DNA标志。根据这一想法，我们 证明了核小体竞争性结合并抑制DNA诱导的细胞质刺激， DNA传感器，cGAS，先天免疫系统的组成部分。我们发现在延长的有丝分裂过程中， CGAS被缓慢激活并诱导细胞死亡。不表达cGAS的细胞在生长过程中不太容易死亡。 由紫杉醇诱导的有丝分裂阻滞，紫杉醇常用于癌症化疗。因此，cGAS表达水平 cGAS介导的免疫可能影响紫杉醇的细胞毒效应 在肿瘤上。我们将研究cGAS诱导的细胞死亡背后的机制及其与临床的相关性。 紫杉醇治疗。

Project Summary Proper chromosome segregation during mitosis is fundamental to cell growth and organism development. Failures in this step lead to developmental diseases, immunodeficiency, and cancers. My research program aims to reveal molecular mechanisms critical for chromosome segregation and elucidate the consequences of their failures, which can be exploited to enhance the efficacy of chemotherapeutic treatments. 1) Roles of nucleosome regulators in chromosome segregation: During mitosis, chromosomes dramatically change their functions and morphology to support their segregation. Chromosomes become condensed, while promoting formation of mitotic apparatuses, such as kinetochores and spindle microtubules. Although histones are the most abundant chromatin proteins, the importance of histones in transcriptional regulation makes it challenging to dissect their direct roles in mitosis. Our lab has established a novel method to manipulate histones and evaluate their consequences using Xenopus egg extracts, which recapitulates a variety of chromatin events independently of transcription. We discovered that the chromosomal passenger complex (CPC) must interact with both nucleosomes and microtubules to support spindle assembly. As chromatin proteins regulated by the CPC, we discovered a novel nucleosome-remodeling complex composed of HELLS and CDCA7, relevant to Centromere instability and Facial anomalies (ICF) syndrome. By dissecting the roles of HELLS-CDCA7 and other nucleosome regulators, we will investigate the poorly understood mechanisms and functional significance of mitosis-specific control of nucleosome dynamics and functions. 2) Mechanisms that maintain human centromere integrity: Human centromeres, where kinetochores assemble to capture microtubules, are composed of a long array of repetitive element, α-satellite DNA. We have shown that α-satellite repetitive arrangement becomes unstable in cancer cells and during cellular senescence, and that centromere-binding proteins are important for preserving this arrangement. We will dissect mechanisms that maintain integrity of centromere-associated repetitive elements. 3) Recognition of mitotic failures by the innate immune system: We hypothesize that nucleosomes act as a hallmark that distinguish between genomic DNAs and foreign or aberrant DNAs. Consistent with this idea, we demonstrated that the nucleosome competitively binds and inhibits DNA-induced stimulation of the cytoplasmic DNA sensor, cGAS, a component of the innate immune system. We showed that during extended mitosis, cGAS is slowly activated and induce cell death. Cells that do not express cGAS are less prone to die during mitotic arrest induced by taxol, which is frequently used in cancer chemotherapy. Thus, cGAS expression level could be a predictor of the efficacy of taxol, and cGAS mediated-immunity may affect cytotoxic effect of taxol on tumors. We will investigate mechanisms behind cGAS-induced cell death and its relevance to clinical treatment with taxol.