CDK1 controls CHMP7-dependent nuclear envelope reformation.
CDK1 controls CHMP7-dependent nuclear envelope reformation.
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DOI：
10.7554/elife.59999
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发表时间：
2021-07-21
期刊：
影响因子：
7.7
通讯作者：
Carlton JG
中科院分区：
文献类型：
--
作者：
Gatta AT;Olmos Y;Stoten CL;Chen Q;Rosenthal PB;Carlton JG
通过纺锤体微管的膜密封和分解，转运蛋白-III（ESCRT-III）机器所需的内体分选复合物已成为有丝分裂退出期间密封的核膜（NE）再生的关键参与者，并在间期破裂期间修复该细胞器。ESCRT-III在NE的组装在有丝分裂（M）退出期间瞬时发生，并且当CHMP 7（ER定位的ESCRT-II/ESCRT-III杂合蛋白）与内核膜（INM）蛋白LEM 2相互作用时启动。虽然经典的核质转运机制已被提出在间期分离LEM 2和CHMP 7，但尚不清楚当NE和ER身份混合时，CHMP 7组装在有丝分裂中如何被抑制。在这里，我们使用活细胞成像和蛋白质生物化学来检查这些蛋白质在M退出过程中的生物学。首先，我们发现CHMP 7在M-退出过程中在NE形成的LEM 2团簇的溶解中起着重要的作用。其次，我们表明，CDK 1磷酸化CHMP 7在M-进入Ser 3和Ser 441，这种磷酸化减少CHMP 7与LEM 2的相互作用，限制其组装在M期。我们发现，时空差异的CHMP 7的去磷酸化许可其组装在NE在末期，但限制其组装在ER在这个时候。在没有CDK 1磷酸化的情况下，CHMP 7在M-退出期间在外周ER中经历不适当的组装，捕获LEM 2和下游ESCRT-III组分。最后，我们建立了一个微管网络是ESCRT-III组装在改造核膜。这些数据确定了一个关键的细胞周期控制程序，允许ESCRT-III依赖的核再生。
Through membrane sealing and disassembly of spindle microtubules, the Endosomal Sorting Complex Required for Transport-III (ESCRT-III) machinery has emerged as a key player in the regeneration of a sealed nuclear envelope (NE) during mitotic exit, and in the repair of this organelle during interphase rupture. ESCRT-III assembly at the NE occurs transiently during mitotic (M) exit and is initiated when CHMP7, an ER-localised ESCRT-II/ESCRT-III hybrid protein, interacts with the Inner Nuclear Membrane (INM) protein LEM2. Whilst classical nucleocytoplasmic transport mechanisms have been proposed to separate LEM2 and CHMP7 during interphase, it is unclear how CHMP7 assembly is suppressed in mitosis when NE and ER identities are mixed. Here, we use live cell imaging and protein biochemistry to examine the biology of these proteins during M-exit. Firstly, we show that CHMP7 plays an important role in the dissolution of LEM2 clusters that form at the NE during M-exit. Secondly, we show that CDK1 phosphorylates CHMP7 upon M-entry at Ser3 and Ser441 and that this phosphorylation reduces CHMP7’s interaction with LEM2, limiting its assembly during M-phase. We show that spatiotemporal differences in the dephosphorylation of CHMP7 license its assembly at the NE during telophase, but restrict its assembly on the ER at this time. Without CDK1 phosphorylation, CHMP7 undergoes inappropriate assembly in the peripheral ER during M-exit, capturing LEM2 and downstream ESCRT-III components. Lastly, we establish that a microtubule network is dispensable for ESCRT-III assembly at the reforming nuclear envelope. These data identify a key cell-cycle control programme allowing ESCRT-III-dependent nuclear regeneration.