近日，美国宾夕法尼亚大学教授Ben E. Black等研究人员合作发现，着丝粒染色质的清除标示动粒形成的部位。这一研究成果于2025年1月23日在线发表在国际学术期刊《细胞》上。

通过在人体有丝分裂染色体上使用冷冻电子断层扫描（cryo-ET），研究人员揭示了着丝粒的独特结构：在染色质清除区域内聚集着20-至25纳米的组蛋白核小体相关复合物，这些清除区域将其与周围染色质区分开。着丝粒成分CENP-C和CENP-N对这些复合物的完整性是必需的，同时CENP-C还需要维持染色质清除。研究人员发现，CENP-C在有丝分裂中是必需的，不仅仅是为了动粒组装，这可能反映了它在染色体分离过程中组织内动粒的作用。

研究人员进一步观察到纤维冠的支架结构，这是在未附着的动粒上放大的结构，进而揭示了呈新月形的平行纤维阵列，延伸超过1微米。因此，研究人员揭示了着丝粒染色质的组织如何在动粒形成部位创造清除区域，并阐明了由冠状纤维介导的动粒放大的特征。

据介绍，着丝粒是染色体位点，招募动粒，指导细胞分裂过程中基因组的忠实传播。

附：英文原文

Title: Centromeric chromatin clearings demarcate the site of kinetochore formation

Author: Kathryn Kixmoeller, Ekaterina V. Tarasovetc, Elie Mer, Yi-Wei Chang, Ben E. Black

Issue&Volume: 2025-01-23

Abstract: The centromere is the chromosomal locus that recruits the kinetochore, directing faithful propagation of the genome during cell division. Using cryo-ET on human mitotic chromosomes, we reveal a distinctive architecture at the centromere: clustered 20- to 25-nm nucleosome-associated complexes within chromatin clearings that delineate them from surrounding chromatin. Centromere components CENP-C and CENP-N are each required for the integrity of the complexes, while CENP-C is also required to maintain the chromatin clearing. We find that CENP-C is required in mitosis, not just for kinetochore assembly, likely reflecting its role in organizing the inner kinetochore during chromosome segregation. We further visualize the scaffold of the fibrous corona, a structure amplified at unattached kinetochores, revealing crescent-shaped parallel arrays of fibrils extending >1 μm. Thus, we reveal how the organization of centromeric chromatin creates a clearing at the site of kinetochore formation as well as the nature of kinetochore amplification mediated by corona fibrils.

DOI: 10.1016/j.cell.2024.12.025

Source:https://www.cell.com/cell/abstract/S0092-8674(24)01467-3