Institut Curie, PSL Research University, CNRS, UMR144, Biology of centrosomes and genetic instability lab, 75005 Paris, France; Institut Curie, PSL Research University, CNRS, UMR144, Molecular Mechanisms of Chromosome Dynamics lab, 75005 Paris, France.
Institut Curie, PSL Research University, CNRS, UMR144, Biology of centrosomes and genetic instability lab, 75005 Paris, France.
Curr Biol. 2019 Sep 23;29(18):3072-3080.e5. doi: 10.1016/j.cub.2019.07.052. Epub 2019 Sep 5.
Centromeres and centrosomes are crucial mitotic players. Centromeres are unique chromosomal sites characterized by the presence of the histone H3-variant centromere protein A (CENP-A) [1]. CENP-A recruits the majority of centromere components, collectively named the constitutive centromere associated network (CCAN) [2]. The CCAN is necessary for kinetochore assembly, a multiprotein complex that attaches spindle microtubules (MTs) and is required for chromosome segregation [3]. In most animal cells, the dominant site for MT nucleation in mitosis are the centrosomes, which are composed of two centrioles, surrounded by a protein-rich matrix of electron-dense pericentriolar material (PCM) [4]. The PCM is the site of MT nucleation during mitosis [5]. Even if centromeres and centrosomes are connected via MTs in mitosis, it is not known whether defects in either one of the two structures have an impact on the function of the other. Here, using high-resolution microscopy combined with rapid removal of CENP-A in human cells, we found that perturbation of centromere function impacts mitotic spindle pole integrity. This includes release of MT minus-ends from the centrosome, leading to PCM dispersion and centriole mis-positioning at the spindle poles. Mechanistically, we show that these defects result from abnormal spindle MT dynamics due to defective kinetochore-MT attachments. Importantly, restoring mitotic spindle pole integrity following centromere inactivation lead to a decrease in the frequency of chromosome mis-segregation. Overall, our work identifies an unexpected relationship between centromeres and maintenance of the mitotic pole integrity necessary to ensure mitotic accuracy and thus to maintain genetic stability.
着丝粒和中心体是有丝分裂的关键参与者。着丝粒是独特的染色体位点，其特征是存在组蛋白 H3 变体着丝粒蛋白 A（CENP-A）[1]。CENP-A 招募大多数着丝粒成分，统称为组成性着丝粒相关网络（CCAN）[2]。CCAN 对于动粒组装是必需的，动粒是一个多蛋白复合物，它附着纺锤体微管（MT），对于染色体分离是必需的[3]。在大多数动物细胞中，有丝分裂中 MT 成核的主要位点是中心体，它由两个中心粒组成，周围是富含电子致密的中心粒周围物质（PCM）的蛋白质基质[4]。PCM 是有丝分裂中 MT 成核的部位[5]。即使在有丝分裂中着丝粒和中心体通过 MT 连接，也不知道这两个结构中的任何一个缺陷是否会影响另一个结构的功能。在这里，我们使用高分辨率显微镜结合快速去除人类细胞中的 CENP-A，发现着丝粒功能的缺陷会影响有丝分裂纺锤体极的完整性。这包括 MT 负端从中心体释放，导致 PCM 弥散和中心粒在纺锤体极的位置错误。从机制上讲，我们表明这些缺陷是由于动粒-MT 连接缺陷导致的异常纺锤体 MT 动力学引起的。重要的是，在着丝粒失活后恢复有丝分裂纺锤体极的完整性会导致染色体错误分离的频率降低。总的来说，我们的工作确定了着丝粒和维持有丝分裂极完整性之间的意外关系，这对于确保有丝分裂的准确性和维持遗传稳定性是必要的。
