Loss of RanGEF/Pim1 activity abolishes the orchestration of Ran-mediated mitotic cellular events in S-pombe
Loss of RanGEF/Pim1 activity abolishes the orchestration of Ran-mediated mitotic cellular events in S-pombe
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DOI：
10.1111/j.1365-2443.2005.00919.x
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发表时间：
2006-01-01
期刊：
影响因子：
2.1
通讯作者：
Nishimoto, T
中科院分区：
文献类型：
--
作者：
Hirose, E;Mukai, M;Nishimoto, T
RCC 1是一种具有七叶螺旋桨的保守的染色体蛋白，是介导各种细胞事件的RanGT的GDP/GTP核苷酸交换因子。我们分离了16株温度敏感突变株。pombeRCC 1同源物pim 1（+），通过易错PCR。5个pim 1（ts）突变体均为单一突变。所获得的pim 1（ts）突变和先前报道的突变定位在7个RCC 1重复序列中的相似位点上。这些突变导致Pim 1与Spi 1的结合减少。所有pim 1（ts）突变体显示核质蛋白转运的缺陷，而他们中的大多数表现出正常的mRNA输出。在所有检测的pim 1（ts）中，染色体DNA复制完成。但是，有丝分裂纺锤体的形成被取消，隔膜与核分裂不偶联而异常加宽，从而导致染色体DNA的错误分离和去核细胞的积累。因此，RanGEF/Pim 1的缺陷取消了连续的有丝分裂事件，纺锤体形成，分隔和胞质分裂的编排，这些都是产生两个相同的子细胞所必需的。
RCC1, a conserved chromosomal protein with a seven-bladed propeller is a GDP/GTP nucleotide exchange factor for RanGTPase that mediates various cellular events. We isolated 16 temperature-sensitive (ts) mutants of S. pombeRCC1-homolog, pim1(+), by error-prone PCR. Five pim1(ts) mutants had a single mutation. The obtained pim1(ts) mutations and previously reported mutations were localized on similar sites in seven RCC1 repeats. Those mutations resulted in a reduced binding of Pim1 with Spi1. All pim1(ts) mutants showed a defect in nucleocytoplasmic protein transports, whereas the majority of them showed a normal mRNA export. In all pim1(ts) examined, chromosomal DNA replication was completed. However, mitotic spindle formation was abrogated, the septum was formed being uncoupled with nuclear division and abnormally widened, thus resulting in chromosomal DNA mis-segregation and the accumulation of enucleated cells. As a result, a defect of RanGEF/Pim1 abolished the orchestration of sequential mitotic events, spindle formation, septation and cytokinesis that are essential to produce two identical daughter cells.