Temporal control of nuclear envelope assembly by phosphorylation of lamin B receptor.
Temporal control of nuclear envelope assembly by phosphorylation of lamin B receptor.
复制标题
通过层粘连蛋白B受体的磷酸化对核膜组装的时间控制。
DOI：
10.1091/mbc.e11-03-0199
复制
发表时间：
2011-09
影响因子：
3.3
通讯作者：
Chen RH
中科院分区：
文献类型：
--
作者：
Tseng LC;Chen RH
后生动物的核膜在有丝分裂早期破裂，直到后期才重新形成。Cdk1磷酸化层粘连蛋白B受体不仅可以防止核膜过早组装，还可以促进核膜在核膜分解过程中与染色质的完全解离。后生动物的核膜在有丝分裂时解体，在姐妹染色单体完全分离后的后期重组。这些有丝分裂事件的协调对基因组的稳定性很重要，但核膜重组的时间控制尚不清楚。尽管利用鸡蛋提取物的重构系统已经在体外广泛研究了核形成的步骤，但时间控制只能在体内研究。在这里，我们使用延时显微镜来研究活HeLa细胞的这一过程。我们证明，Cdk1活性可以防止核膜过早组装，并且Cdk1磷酸化核膜蛋白层蛋白B受体（LBR）有助于时间控制。我们进一步确定了LBR核质结构域的一个区域，该区域抑制了蛋白质的过早染色质结合。我们认为这种抑制作用部分是由Cdk1磷酸化介导的。此外，我们发现LBR的染色质结合能力降低以及极光B活性有助于核膜的破坏。我们的研究首次揭示了一种通过修饰整体核膜蛋白来控制核膜重组时间的机制。
The metazoan nuclear envelope breaks down in early mitosis and does not reform until late anaphase. Phosphorylation of lamin B receptor by Cdk1 not only prevents premature nuclear envelope assembly, but also facilitates complete dissociation of the nuclear envelope from the chromatin during nuclear envelope breakdown. The nuclear envelope of metazoans disassembles during mitosis and reforms in late anaphase after sister chromatids have well separated. The coordination of these mitotic events is important for genome stability, yet the temporal control of nuclear envelope reassembly is unknown. Although the steps of nuclear formation have been extensively studied in vitro using the reconstitution system from egg extracts, the temporal control can only be studied in vivo. Here, we use time-lapse microscopy to investigate this process in living HeLa cells. We demonstrate that Cdk1 activity prevents premature nuclear envelope assembly and that phosphorylation of the inner nuclear membrane protein lamin B receptor (LBR) by Cdk1 contributes to the temporal control. We further identify a region in the nucleoplasmic domain of LBR that inhibits premature chromatin binding of the protein. We propose that this inhibitory effect is partly mediated by Cdk1 phosphorylation. Furthermore, we show that the reduced chromatin-binding ability of LBR together with Aurora B activity contributes to nuclear envelope breakdown. Our studies reveal for the first time a mechanism that controls the timing of nuclear envelope reassembly through modification of an integral nuclear membrane protein.