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Updated: Jan 19, 2026
Spatiotemporal Analysis of Cytokinetic Events in Fission Yeast
Published on: February 20, 2017
The phosphatase inhibitor Sds23 regulates cell division symmetry in fission yeast
Katherine L Schutt1, James B Moseley1
1Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover, NH 03755.
Abstract:
Animal and fungal cells divide through the assembly, anchoring, and constriction of a contractile actomyosin ring (CAR) during cytokinesis. The timing and position of the CAR must be tightly controlled to prevent defects in cell division, but many of the underlying signaling events remain unknown. The conserved heterotrimeric protein phosphatase PP2A controls the timing of events in mitosis, and upstream pathways including Greatwall-Ensa regulate PP2A activity. A role for PP2A in CAR regulation has been less clear, although loss of PP2A in yeast causes defects in cytokinesis. Here, we report that Sds23, an inhibitor of PP2A family protein phosphatases, promotes the symmetric division of fission yeast cells through spatial control of cytokinesis. We found that sds23∆ cells divide asymmetrically due to misplaced CAR assembly, followed by sliding of the CAR away from its assembly site. These mutant cells exhibit delayed recruitment of putative CAR anchoring proteins including the glucan synthase Bgs1. Our observations likely reflect a broader role for regulation of PP2A in cell polarity and cytokinesis because sds23∆ phenotypes were exacerbated when combined with mutations in the fission yeast Ensa homologue, Igo1. These results identify the PP2A regulatory network as a critical component in the signaling pathways coordinating cytokinesis.
Insights
Sds23 regulates cell division by controlling the position of the contractile actomyosin ring (CAR) during cytokinesis. Loss of Sds23 causes asymmetric cell division due to misplaced CAR assembly, highlighting PP2A regulation
Area of Science:
- Cell Biology
- Molecular Biology
- Genetics
Background:
- Cytokinesis relies on a contractile actomyosin ring (CAR) for cell division in animal and fungal cells.
- Precise control of CAR assembly, anchoring, and constriction is crucial for preventing cell division defects.
- The protein phosphatase PP2A regulates mitotic timing, but its role in CAR regulation is less understood.
Purpose of the Study:
- To investigate the role of Sds23, a PP2A inhibitor, in regulating cytokinesis and cell division symmetry in fission yeast.
- To elucidate the signaling pathways involving PP2A in the spatial control of the contractile actomyosin ring.
Main Methods:
- Genetic analysis of fission yeast mutants, including sds23∆ and igo1.
- Microscopy to observe CAR assembly, positioning, and dynamics.
- Analysis of protein recruitment, including glucan synthase Bgs1.
Main Results:
- sds23∆ cells exhibit asymmetric division due to misplaced CAR assembly and subsequent sliding.
- Mutant cells show delayed recruitment of CAR anchoring proteins like Bgs1.
- Phenotypes are exacerbated when combined with mutations in the Ensa homologue, Igo1, suggesting a broader PP2A regulatory role.
Conclusions:
- Sds23 promotes symmetric cell division through spatial control of cytokinesis.
- The PP2A regulatory network is essential for coordinating signaling pathways in cytokinesis.
- Regulation of PP2A activity is critical for cell polarity and proper cell division.
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