Wellcome Centre for Cell Biology, University of Edinburgh, Edinburgh, UK.
Ludwig Institute for Cancer Research, La Jolla, CA, USA.
Nat Commun. 2024 Oct 21;15(1):9085. doi: 10.1038/s41467-024-52964-5.
Multiple microtubule-directed activities concentrate on mitotic chromosomes to ensure their faithful segregation. These include couplers and dynamics regulators localized at the kinetochore, the microtubule interface built on centromeric chromatin, as well as motor proteins recruited to kinetochores and chromatin. Here, we describe an in vivo approach in the C. elegans one-cell embryo in which removal of the major microtubule-directed activities on mitotic chromosomes is compared to the selective presence of individual activities. Our approach reveals that the kinetochore dynein module, comprised of cytoplasmic dynein and its kinetochore-specific adapters, is sufficient to biorient chromosomes; by contrast, this module is unable to support congression. In coordination with orientation, the dynein module directs removal of outermost kinetochore components, including dynein itself, independently of the other microtubule-directed activities and kinetochore-localized protein phosphatase 1. These observations indicate that the kinetochore dynein module is sufficient to biorient chromosomes and to direct remodeling of the outer kinetochore in a microtubule attachment state-sensitive manner.
多种微管定向活性集中在有丝分裂染色体上，以确保它们的忠实分离。这些活动包括位于动粒上的偶联蛋白和动力学调节剂、建立在着丝粒染色质上的微管界面，以及募集到动粒和染色质的马达蛋白。在这里，我们描述了一种在秀丽隐杆线虫单细胞胚胎中的体内方法，其中比较了有丝分裂染色体上主要微管定向活性的去除与单个活性的选择性存在。我们的方法表明，由细胞质动力蛋白及其动粒特异性衔接蛋白组成的动粒动力蛋白模块足以使染色体双取向；相比之下，该模块无法支持汇聚。在定向协调下，动力蛋白模块指导最外层动粒成分的去除，包括动力蛋白本身，这与其他微管定向活性和动粒定位的蛋白磷酸酶 1 无关。这些观察结果表明，动粒动力蛋白模块足以使染色体双取向，并以微管附着状态敏感的方式指导外动粒的重塑。
