Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh, UK.
Cell Biology Unit, Institute of Innovative Research, Tokyo Institute of Technology, Yokohama, Japan.
EMBO J. 2018 Mar 15;37(6). doi: 10.15252/embj.201797677. Epub 2018 Feb 21.
The chromosomal passenger complex (CPC) is directed to centromeres during mitosis via binding to H3T3ph and Sgo1. Whether and how heterochromatin protein 1α (HP1α) influences CPC localisation and function during mitotic entry is less clear. Here, we alter HP1α dynamics by fusing it to a CENP-B DNA-binding domain. Tethered HP1 strongly recruits the CPC, destabilising kinetochore-microtubule interactions and activating the spindle assembly checkpoint. During mitotic exit, the tethered HP1 traps active CPC at centromeres. These HP1-CPC clusters remain catalytically active throughout the subsequent cell cycle. We also detect interactions between endogenous HP1 and the CPC during G HP1α and HP1γ cooperate to recruit the CPC to active foci in a CDK1-independent process. Live cell tracking with Fab fragments reveals that H3S10ph appears well before H3T3 is phosphorylated by Haspin kinase. Our results suggest that HP1 may concentrate and activate the CPC at centromeric heterochromatin in G before Aurora B-mediated phosphorylation of H3S10 releases HP1 from chromatin and allows pathways dependent on H3T3ph and Sgo1 to redirect the CPC to mitotic centromeres.
染色体乘客复合物（CPC）通过与 H3T3ph 和 Sgo1 结合，在有丝分裂期间被导向着丝粒。然而，异染色质蛋白 1α（HP1α）在有丝分裂进入时如何影响 CPC 的定位和功能尚不清楚。在这里，我们通过将其融合到 CENP-B DNA 结合域中来改变 HP1α 的动力学。固定的 HP1 可强烈招募 CPC，破坏动粒微管相互作用并激活纺锤体组装检查点。在有丝分裂退出期间，固定的 HP1 将活性 CPC 捕获在着丝粒上。这些 HP1-CPC 簇在随后的整个细胞周期中保持催化活性。我们还在 G 期检测到内源性 HP1 和 CPC 之间的相互作用，HP1α 和 HP1γ 合作以在 CDK1 独立的过程中招募 CPC 到活性焦点。使用 Fab 片段进行活细胞追踪表明，H3S10ph 的出现远早于 Haspin 激酶磷酸化 H3T3。我们的结果表明，在 Aurora B 介导的 H3S10 磷酸化释放 HP1 脱离染色质并允许依赖 H3T3ph 和 Sgo1 的途径将 CPC 重定向到有丝分裂着丝粒之前，HP1 可能在 G 期将 CPC 集中并激活到着丝粒异染色质上。
