Haase Julian, Aktar Koly, Bonner Mary Kate, Colin Leonard, Gupta Hindol, Marinoni Briana E, Morgan David O, Kelly Alexander E
Laboratory of Biochemistry and Molecular Biology, Center for Cancer Research, National Cancer Institute, NIH, 37 Convent Drive, Bethesda, MD 20892, USA.
Department of Physiology, University of California, San Francisco, 600 16(th) Street, San Francisco, CA 94148, USA.
Curr Biol. 2025 Jul 22. doi: 10.1016/j.cub.2025.07.011.
The constitutive centromere-associated network (CCAN) of the inner kinetochore links CENP-A-containing nucleosomes of the centromere to the outer kinetochore, ensuring accurate chromosome segregation during mitosis. CCAN binding at the centromere is stabilized upon mitotic entry, but the underlying mechanisms remain unclear. Here, we demonstrate that cohesin is essential for CCAN stability. The chromosomal passenger complex (CPC), independently of its kinase subunit Aurora B, regulates cohesin-mediated CCAN stability via heterochromatin protein-1 (HP1), Haspin kinase, and phosphorylation of the cohesin-release factor WAPL, which weakens WAPL's affinity for PDS5B. While cohesin depletion disrupts CCAN stability, neither separase-mediated cohesin cleavage nor depletion of the cohesion-essential Esco2 acetyltransferase affects CCAN stability, indicating that cohesin stabilizes the CCAN independently of sister chromatid cohesion. Furthermore, we show that WAPL phosphorylation maintains a centromere-proximal pool of cohesin and promotes the formation of the primary constriction. These findings establish a non-cohesive function of cohesin in stabilizing the CCAN during mitosis and suggest that cohesin-mediated organization of centromeric chromatin strengthens kinetochore engagement to ensure faithful chromosome segregation.
内着丝粒的组成型着丝粒相关网络（CCAN）将着丝粒中含CENP - A的核小体与外着丝粒相连，确保有丝分裂期间染色体的准确分离。有丝分裂开始时，CCAN在着丝粒处的结合得以稳定，但潜在机制仍不清楚。在此，我们证明黏连蛋白对于CCAN的稳定性至关重要。染色体乘客复合体（CPC）独立于其激酶亚基Aurora B，通过异染色质蛋白1（HP1）、Haspin激酶以及黏连蛋白释放因子WAPL的磷酸化来调节黏连蛋白介导的CCAN稳定性，这削弱了WAPL对PDS5B的亲和力。虽然黏连蛋白缺失会破坏CCAN稳定性，但分离酶介导的黏连蛋白切割以及黏连必不可少的Esco2乙酰转移酶的缺失均不影响CCAN稳定性，这表明黏连蛋白稳定CCAN独立于姐妹染色单体黏连。此外，我们表明WAPL磷酸化维持着着丝粒近端的黏连蛋白池，并促进主缢痕的形成。这些发现确立了黏连蛋白在有丝分裂期间稳定CCAN的非黏连功能，并表明黏连蛋白介导的着丝粒染色质组织增强了着丝粒的结合，以确保忠实的染色体分离。
