P. J. Russell

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In fission yeast the onset of mitosis is brought about by Cdc2/Cdc13 kinase, which is inhibited by the Wee1/Mik1 tyrosine kinases and activated by Cdc25 tyrosine phosphatase. This control network integrates many signals, including those that monitor DNA replication, DNA damage and cell size. We report here that a fission yeast MAP kinase pathway links the(More)
The stress-activated Wis1-Spc1 protein kinase cascade links mitotic control with environmental signals in Schizosaccharomyces pombe. Fission yeast spc1- mutants are delayed in G2 during normal growth and undergo G2 arrest when exposed to osmotic or oxidative stress. Here we report that Spc1 also has an important role in regulating sexual development in S.(More)
Fission yeast wee1- mutants initiate mitosis at half the cell size of wild type. The wee1+ activity is required to prevent lethal premature mitosis in cells that overproduce the mitotic inducer cdc25+. This lethal phenotype was used to clone wee1+ by complementation. When wee1+ expression is increased, mitosis is delayed until cells grow to a larger size.(More)
DNA damage activates a cell-cycle checkpoint that prevents mitosis while DNA repair is under way. The protein Chk1 enforces this checkpoint by phosphorylating the mitotic inducer Cdc25. Phosphorylation of Cdc25 by Chk1 creates a binding site in Cdc25 for 14-3-3 proteins, but it is not known how 14-3-3 proteins regulate Cdc25. Rad24 is a 14-3-3 protein that(More)
The breast cancer susceptibility gene BRCA2 on chromosome 13q12-13 has recently been identified. Germline mutations of BRCA2 are predicted to account for approximately 35% of families with multiple case, early onset female breast cancer, and they are also associated with an increased risk of male breast cancer, ovarian cancer, prostate cancer and pancreatic(More)
Cdc2, the kinase that induces mitosis, is regulated by checkpoints that couple mitosis to the completion of DNA replication and repair. The repair checkpoint kinase Chk1 regulates Cdc25, a phosphatase that activates Cdc2. Effectors of the replication checkpoint evoked by hydroxyurea (HU) are unknown. Treatment of fission yeast with HU stimulated the kinase(More)
Arrest of the cell cycle at the G2 checkpoint, induced by DNA damage, requires inhibitory phosphorylation of the kinase Cdc2 in both fission yeast and human cells. The kinase Wee1 and the phosphatase Cdc25, which regulate Cdc2 phosphorylation, were evaluated as targets of Chk1, a kinase essential for the checkpoint. Fission yeast cdc2-3w Deltacdc25 cells,(More)
Spc1, an osmotic-stress-stimulated mitogen-activated protein kinase (MAPK) homolog in the fission yeast Schizosaccharomyces pombe, is required for the induction of mitosis and survival in high-osmolarity conditions. Spc1, also known as Sty1, is activated by Wis1 MAPK kinase and inhibited by Pyp1 tyrosine phosphatase. Spc1 is most closely related to(More)
In the fission yeast S. pombe the cdc25+ gene function is required to initiate mitosis. We have cloned the cdc25+ gene and have found that increased cdc25+ expression causes mitosis to initiate at a reduced cell size. This shows that cdc25+ functions as a dosage-dependent inducer in mitotic control, the first such mitotic control element to be specifically(More)
In fission yeast, the M-phase inducing kinase, a complex of p34cdc2 and cyclin B, is maintained in an inhibited state during interphase due to the phosphorylation of Cdc2 at Tyr15. This phosphorylation is believed to be carried out primarily by the Wee1 kinase. In human cells the negative regulation of p34cdc2/cyclin B is more complex, in that Cdc2 is(More)