Saccharomyces cerevisiae Mob1p is required for cytokinesis and mitotic exit
Saccharomyces cerevisiae Mob1p is required for cytokinesis and mitotic exit
复制标题
DOI：
10.1128/mcb.21.20.6972-6983.2001
复制
发表时间：
2001-10-01
影响因子：
5.3
通讯作者：
Winey, M
中科院分区：
文献类型：
--
作者：
Luca, FC;Mody, M;Winey, M
酿酒酵母有丝分裂退出网络(MAN)是一组保守的基因，通过调节有丝分裂周期蛋白的降解和细胞周期蛋白依赖性激酶(CDK)的失活，介导从有丝分裂到G细胞的转变。在这里，我们证明，除了有丝分裂退出，酿酒酵母男性MOB1基因是胞质分裂和细胞分离所必需的。在没有有丝分裂退出缺陷的条件下，mob1突变体的胞质分裂缺陷明显。活细胞观察表明，酵母肌球蛋白II，Myo1p存在于芽颈的收缩环中，但环不能收缩和解体。细胞质分裂缺陷持续了几个有丝分裂周期，导致细胞核正确分离但肌动球蛋白环未收缩的细胞链。胞质分裂蛋白CDc3p(一种Septin)、肌动蛋白和Iqg1p/Cyk1p(一种IQGAP样蛋白)似乎正确地定位于mob1突变体中，表明MOB1在肌动球蛋白环组装之后发挥功能。我们还研究了Mob1p在细胞周期中的亚细胞分布，发现Mob1p在细胞分裂中期首先定位于纺锤体，然后在细胞质分裂之前和过程中定位于芽颈的环。Mob Ip的芽颈定位需要CDC3、MEN基因CDC5、CDC14、CDC15和DBF2以及纺锤体基因NUD1，但与MYO1无关。在cdc15和nud1突变体中，Mob1p在两个纺锤体极上的定位被取消，而在cdc5和cdc14突变体中被干扰。这些结果表明，男性在有丝分裂到G期、控制细胞周期蛋白-CDK失活和胞质分裂的过程中发挥作用。
The Saccharomyces cerevisiae mitotic exit network (MEN) is a conserved set of genes that mediate the transition from mitosis to G, by regulating mitotic cyclin degradation and the inactivation of cyclin-dependent kinase (CDK). Here, we demonstrate that, in addition to mitotic exit, S. cerevisiae MEN gene MOB1 is required for cytokinesis and cell separation. The cytokinesis defect was evident in mob1 mutants under conditions in which there was no mitotic-exit defect. Observation of live cells showed that yeast myosin II, Myo1p, was present in the contractile ring at the bud neck but that the ring failed to contract and disassemble. The cytokinesis defect persisted for several mitotic cycles, resulting in chains of cells with correctly segregated nuclei but with uncontracted actomyosin rings. The cytokinesis proteins Cdc3p (a septin), actin, and Iqg1p/Cyk1p (an IQGAP-like protein) appeared to correctly localize in mob1 mutants, suggesting that MOB1 functions subsequent to actomyosin ring assembly. We also examined the subcellular distribution of Mob1p during the cell cycle and found that Mob1p first localized to the spindle pole bodies during mid-anaphase and then localized to a ring at the bud neck just before and during cytokinesis. Localization of Mob Ip to the bud neck required CDC3, MEN genes CDC5, CDC14, CDC15, and DBF2, and spindle pole body gene NUD1 but was independent of MYO1. The localization of Mob1p to both spindle poles was abolished in cdc15 and nud1 mutants and was perturbed in cdc5 and cdc14 mutants. These results suggest that the MEN functions during the mitosis-to-G, transition to control cyclin-CDK inactivation and cytokinesis.