Dataset Information

The fission yeast dma1 gene is a component of the spindle assembly checkpoint, required to prevent septum formation and premature exit from mitosis if spindle function is compromised.

ABSTRACT: Premature initiation of cytokinesis can lead to loss of chromosomes, and 'cutting' of the nucleus. Therefore, the proper spatial and temporal co-ordination of mitosis and cytokinesis is essential for maintaining the integrity of the genome. The fission yeast cdc16 gene is implicated both in the spindle assembly checkpoint and control of septum formation. To identify other proteins involved in these controls, we have isolated multicopy suppressors of the cdc16-116 mutation, and the characterization of one of these, dma1 (defective in mitotic arrest), is presented here. dma1 is not an essential gene, but in a dma1 null background (dma1-D1) the function of the spindle assembly checkpoint is compromised. If assembly of the spindle is prevented, dma1-D1 cells do not arrest, the activity of cdc2 kinase decays and cells form a division septum without completing a normal mitosis. dma1-D1 cells also show an increased rate of chromosome loss during exponential growth. Upon ectopic expression from an inducible promoter, dma1p delays progress through mitosis and inhibits septum formation, giving rise to elongated, multinucleate cells. We propose that dma1 is a component of the spindle assembly checkpoint, required to prevent septum formation and premature exit from mitosis if spindle function is impaired.

SUBMITTER: Murone M

PROVIDER: S-EPMC452485 | biostudies-other | 1996 Dec

REPOSITORIES: biostudies-other

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The fission yeast dma1 gene is a component of the spindle assembly checkpoint, required to prevent septum formation and premature exit from mitosis if spindle function is compromised.

Murone M M Simanis V V

The EMBO journal 19961201 23

Premature initiation of cytokinesis can lead to loss of chromosomes, and 'cutting' of the nucleus. Therefore, the proper spatial and temporal co-ordination of mitosis and cytokinesis is essential for maintaining the integrity of the genome. The fission yeast cdc16 gene is implicated both in the spindle assembly checkpoint and control of septum formation. To identify other proteins involved in these controls, we have isolated multicopy suppressors of the cdc16-116 mutation, and the characterizati ...[more]

PMID: 8978687

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Project description:It is widely accepted in eukaryotes that the cleavage furrow only initiates after mitosis completion. In fission yeast, cytokinesis requires the synthesis of a septum tightly coupled to cleavage furrow ingression. The current cytokinesis model establishes that simultaneous septation and furrow ingression only initiate after spindle breakage and mitosis exit. Thus, this model considers that although Cdk1 is inactivated at early-anaphase, septation onset requires the long elapsed time until mitosis completion and full activation of the Hippo-like SIN pathway. Here, we studied the precise timing of septation onset regarding mitosis by exploiting both the septum-specific detection with the fluorochrome calcofluor and the high-resolution electron microscopy during anaphase and telophase. Contrarily to the existing model, we found that both septum and cleavage furrow start to ingress at early anaphase B, long before spindle breakage, with a slow ingression rate during anaphase B, and greatly increasing after telophase onset. This shows that mitosis and cleavage furrow ingression are not concatenated but simultaneous events in fission yeast. We found that the timing of septation during early anaphase correlates with the cell size and is regulated by the corresponding levels of SIN Etd1 and Rho1. Cdk1 inactivation was directly required for timely septation in early anaphase. Strikingly the reduced SIN activity present after Cdk1 loss was enough to trigger septation by immediately inducing the medial recruitment of the SIN kinase complex Sid2-Mob1. On the other hand, septation onset did not depend on the SIN asymmetry establishment, which is considered a hallmark for SIN activation. These results recalibrate the timing of key cytokinetic events in fission yeast; and unveil a size-dependent control mechanism that synchronizes simultaneous nuclei separation with septum and cleavage furrow ingression to safeguard the proper chromosome segregation during cell division.

Dataset Information

The fission yeast dma1 gene is a component of the spindle assembly checkpoint, required to prevent septum formation and premature exit from mitosis if spindle function is compromised.

Publications

The fission yeast dma1 gene is a component of the spindle assembly checkpoint, required to prevent septum formation and premature exit from mitosis if spindle function is compromised.

Similar Datasets

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