Chromosome Instability and Dynamics Laboratory, Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal.
Center for Mathematics, Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto, Portugal.
Science. 2014 Jul 18;345(6194):332-336. doi: 10.1126/science.1251121. Epub 2014 Jun 12.
Accurate chromosome segregation during mitosis requires the physical separation of sister chromatids before nuclear envelope reassembly (NER). However, how these two processes are coordinated remains unknown. Here, we identified a conserved feedback control mechanism that delays chromosome decondensation and NER in response to incomplete chromosome separation during anaphase. A midzone-associated Aurora B gradient was found to monitor chromosome position along the division axis and to prevent premature chromosome decondensation by retaining Condensin I. PP1/PP2A phosphatases counteracted this gradient and promoted chromosome decondensation and NER. Thus, an Aurora B gradient appears to mediate a surveillance mechanism that prevents chromosome decondensation and NER until effective separation of sister chromatids is achieved. This allows the correction and reintegration of lagging chromosomes in the main nuclei before completion of NER.
在有丝分裂过程中，准确的染色体分离需要在核膜重新组装（NER）之前将姐妹染色单体物理分离。然而，这两个过程是如何协调的仍然未知。在这里，我们发现了一种保守的反馈控制机制，该机制可以延迟染色体解凝聚和 NER，以响应后期姐妹染色单体分离不完全。发现一个位于中部的 Aurora B 梯度可以沿分裂轴监测染色体位置，并通过保留凝聚素 I 来防止过早的染色体解凝聚。PP1/PP2A 磷酸酶拮抗这种梯度，并促进染色体解凝聚和 NER。因此，Aurora B 梯度似乎介导了一种监控机制，该机制可以防止染色体解凝聚和 NER，直到实现姐妹染色单体的有效分离。这使得滞后染色体在 NER 完成之前可以在主核中得到纠正和重新整合。
