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Mitotic defects in fission yeast lipid metabolism 'cut' mutants are suppressed by ammonium chloride
Róbert Zach1, Jarmila Tvaružková1, Martin Schätz1,2
1Department of Cell Biology, Faculty of Science, Charles University, Prague, Czech Republic.
Abstract:
Fission yeast 'cut' mutants show defects in temporal coordination of nuclear division with cytokinesis, resulting in aberrant mitosis and lethality. Among other causes, the 'cut' phenotype can be triggered by genetic or chemical perturbation of lipid metabolism, supposedly resulting in shortage of membrane phospholipids and insufficient nuclear envelope expansion during anaphase. Interestingly, penetrance of the 'cut' phenotype in mutants of the transcription factor cbf11 and acetyl-coenzyme A carboxylase cut6, both related to lipid metabolism, is highly dependent on growth media, although the specific nutrient(s) affecting 'cut' occurrence is not known. In this study, we set out to identify the growth media component(s) responsible for 'cut' phenotype suppression in Δcbf11 and cut6-621 cells. We show that mitotic defects occur rapidly in Δcbf11 cells upon shift from the minimal EMM medium ('cut' suppressing) to the complex YES medium ('cut' promoting). By growing cells in YES medium supplemented with individual EMM components, we identified ammonium chloride, an efficiently utilized nitrogen source, as a specific and potent suppressor of the 'cut' phenotype in both Δcbf11 and cut6-621. Furthermore, we found that ammonium chloride boosts lipid droplet formation in wild-type cells. Our findings suggest a possible involvement of nutrient-responsive signaling in 'cut' suppression.
Insights
Ammonium chloride suppresses
Area of Science:
- Cell biology
- Molecular genetics
- Biochemistry
Background:
- Fission yeast 'cut' mutants exhibit defects in nuclear division and cytokinesis coordination.
- Perturbations in lipid metabolism can induce 'cut' phenotypes, potentially due to phospholipid shortages and impaired nuclear envelope expansion.
- The 'cut' phenotype's occurrence is sensitive to growth media, but the specific nutrients involved remain unidentified.
Purpose of the Study:
- Identify specific growth media components that suppress the 'cut' phenotype in fission yeast mutants.
- Investigate the role of nutrient availability in regulating cell division and lipid metabolism.
Main Methods:
- Comparative growth analysis of Δcbf11 and cut6-621 mutants on different media (EMM vs. YES).
- Systematic supplementation of YES medium with individual components from EMM medium.
- Microscopic observation of mitotic defects and lipid droplet formation in wild-type and mutant cells.
Main Results:
- Ammonium chloride, a nitrogen source, was identified as a potent suppressor of the 'cut' phenotype in both Δcbf11 and cut6-621 mutants.
- Mitotic defects in Δcbf11 cells appeared rapidly upon transfer from 'cut'-suppressing EMM to 'cut'-promoting YES medium.
- Ammonium chloride treatment increased lipid droplet formation in wild-type fission yeast cells.
Conclusions:
- Ammonium chloride specifically suppresses the 'cut' phenotype in fission yeast mutants related to lipid metabolism.
- Nutrient-responsive signaling pathways may play a role in regulating cell division and mitigating 'cut' phenotypes.
- Findings suggest a link between nitrogen availability, lipid metabolism, and the coordination of nuclear division with cytokinesis.