Department of Systems Biology, Harvard Medical School, Boston, MA 02115.
Department of Physics, Harvard University, Cambridge, MA 02138.
Proc Natl Acad Sci U S A. 2024 Jun 18;121(25):e2323009121. doi: 10.1073/pnas.2323009121. Epub 2024 Jun 14.
Error correction is central to many biological systems and is critical for protein function and cell health. During mitosis, error correction is required for the faithful inheritance of genetic material. When functioning properly, the mitotic spindle segregates an equal number of chromosomes to daughter cells with high fidelity. Over the course of spindle assembly, many initially erroneous attachments between kinetochores and microtubules are fixed through the process of error correction. Despite the importance of chromosome segregation errors in cancer and other diseases, there is a lack of methods to characterize the dynamics of error correction and how it can go wrong. Here, we present an experimental method and analysis framework to quantify chromosome segregation error correction in human tissue culture cells with live cell confocal imaging, timed premature anaphase, and automated counting of kinetochores after cell division. We find that errors decrease exponentially over time during spindle assembly. A coarse-grained model, in which errors are corrected in a chromosome-autonomous manner at a constant rate, can quantitatively explain both the measured error correction dynamics and the distribution of anaphase onset times. We further validated our model using perturbations that destabilized microtubules and changed the initial configuration of chromosomal attachments. Taken together, this work provides a quantitative framework for understanding the dynamics of mitotic error correction.
纠错对于许多生物系统至关重要,对于蛋白质功能和细胞健康也至关重要。在有丝分裂过程中,需要进行纠错以忠实遗传遗传物质。当纺锤体正常运作时,它可以以高精度将等量的染色体分配到子细胞中。在纺锤体组装过程中,许多最初错误的动粒和微管之间的连接通过纠错过程得以固定。尽管染色体分离错误在癌症和其他疾病中很重要,但缺乏描述纠错动力学及其出错方式的方法。在这里,我们通过活细胞共聚焦成像、提前过早的后期和细胞分裂后自动计数动粒,提出了一种在人类组织培养细胞中定量测量染色体分离纠错的实验方法和分析框架。我们发现,在纺锤体组装过程中,错误随时间呈指数级减少。一个粗粒化模型表明,错误以恒定的速率在染色体自主的方式下被纠正,该模型可以定量解释测量的纠错动力学和后期起始时间的分布。我们还使用微管不稳定和改变染色体附着的初始配置的扰动来验证我们的模型。总之,这项工作为理解有丝分裂纠错的动力学提供了一个定量框架。
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