Regulation of Cell Cycle Progression by Swe1p and Hog1p Following Hypertonic Stress
| Autor: | Michael C. Gustin, Mireille Perret, Karen S. Fang, Matthew R. Alexander, B. Maureen Craig, Mike Tyers |
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| Rok vydání: | 2001 |
| Předmět: |
G2 Phase
Saccharomyces cerevisiae Proteins Hypertonic Solutions Cell Cycle Proteins Article Fungal Proteins Yeasts ASK1 Phosphorylation Kinase activity Protein kinase A Molecular Biology Cyclin-dependent kinase 1 biology Kinase Cell Cycle Cyclin-dependent kinase 2 Cell Biology Protein-Tyrosine Kinases Cell cycle Cell biology Enzyme Activation Hypertonic Stress biology.protein Mitogen-Activated Protein Kinases CDC28 Protein Kinase S cerevisiae |
| Zdroj: | Molecular Biology of the Cell. 12:53-62 |
| ISSN: | 1939-4586 1059-1524 |
| Popis: | Exposure of yeast cells to an increase in external osmolarity induces a temporary growth arrest. Recovery from this stress is mediated by the accumulation of intracellular glycerol and the transcription of several stress response genes. Increased external osmolarity causes a transient accumulation of 1N and 2N cells and a concomitant depletion of S phase cells. Hypertonic stress triggers a cell cycle delay in G2 phase cells that appears distinct from the morphogenesis checkpoint, which operates in early S phase cells. Hypertonic stress causes a decrease in CLB2 mRNA, phosphorylation of Cdc28p, and inhibition of Clb2p-Cdc28p kinase activity, whereas Clb2 protein levels are unaffected. Like the morphogenesis checkpoint, the osmotic stress-induced G2 delay is dependent upon the kinase Swe1p, but is not tightly correlated with inhibition of Clb2p-Cdc28p kinase activity. Thus, deletion of SWE1 does not prevent the hypertonic stress-induced inhibition of Clb2p-Cdc28p kinase activity. Mutation of the Swe1p phosphorylation site on Cdc28p (Y19) does not fully eliminate the Swe1p-dependent cell cycle delay, suggesting that Swe1p may have functions independent of Cdc28p phosphorylation. Conversely, deletion of the mitogen-activated protein kinase HOG1 does prevent Clb2p-Cdc28p inhibition by hypertonic stress, but does not block Cdc28p phosphorylation or alleviate the cell cycle delay. However, Hog1p does contribute to proper nuclear segregation after hypertonic stress in cells that lack Swe1p. These results suggest a hypertonic stress-induced cell cycle delay in G2 phase that is mediated in a novel way by Swe1p in cooperation with Hog1p. |
| Databáze: | OpenAIRE |
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