Fission yeast nucleolar protein Dnt1 regulates G2/M transition and cytokinesis through downregulating Wee1 kinase

Abstract

There was an error published in J. Cell Sci. 126, 4995-5004.One source of funding was accidentally omitted. The correct funding section is as shown below. FundingThis work was supported by the National Institutes of Health [grant number Summary Cytokinesis involves temporally and spatially coordinated action of the cell cycle, cytoskeletal and membrane systems to achieve separation of daughter cells. The septation initiation network (SIN) and mitotic exit network (MEN) signaling pathways regulate cytokinesis and mitotic exit in the yeasts Schizosaccharomyces pombe and Saccharomyces cerevisiae, respectively. Previously, we have shown that in fission yeast, the nucleolar protein Dnt1 negatively regulates the SIN pathway in a manner that is independent of the Cdc14-family phosphatase Clp1/Flp1, but how Dnt1 modulates this pathway has remained elusive. By contrast, it is clear that its budding yeast relative, Net1/Cfi1, regulates the homologous MEN signaling pathway by sequestering Cdc14 phosphatase in the nucleolus before mitotic exit. In this study, we show that dnt1 + positively regulates G2/M transition during the cell cycle. By conducting epistasis analyses to measure cell length at septation in double mutant (for dnt1 and genes involved in G2/M control) cells, we found a link between dnt1 + and wee1 + . Furthermore, we showed that elevated protein levels of the mitotic inhibitor Wee1 kinase and the corresponding attenuation in Cdk1 activity is responsible for the rescuing effect of dnt1D on SIN mutants. Finally, our data also suggest that Dnt1 modulates Wee1 activity in parallel with SCF-mediated Wee1 degradation. Therefore, this study reveals an unexpected missing link between the nucleolar protein Dnt1 and the SIN signaling pathway, which is mediated by the Cdk1 regulator Wee1 kinase. Our findings also define a novel mode of regulation of Wee1 and Cdk1, which is important for integration of the signals controlling the SIN pathway in fission yeast.

F-box proteins Pof3 and Pof1 regulate Wee1 degradation and mitotic entry in fission yeast

“…1A). This strategy was employed to monitor the abundance of Wee1 protein because it has been used reliably in previous studies (Keifenheim et al, 2017;Yu et al, 2013). Strikingly, our quantitative measurements indicated that Wee1 was significantly stabilized in the pof3Δ and pof1-6 mutants, but not in the other F-box protein deletion mutants examined (Fig.…”

“…G418 disulfate (Sigma-Aldrich), hygromycin B (Sangon Biotech) or nourseothiricin (clonNAT; Werner BioAgents) was used at a final concentration of 100 μg/ml where appropriate. Serial-dilution drop tests for growth were performed as previously described (Yu et al, 2013).…”

“…It has been shown that the level of fission yeast wee1 + mRNA does not fluctuate during the cell cycle, but that the protein level of Wee1 oscillates, with its peak at S and G 2 phases and a significant drop at M phase (Aligue et al, 1997). We previously demonstrated that Wee1 protein in S. pombe is more stabilized in proteasome mutant mts3-1 or slightly stabilized in SCF component mutant skp1-A7 (Yu et al, 2013), which strongly suggests that the SCF and proteasome mediate Wee1 proteolysis. Consistently, we observed that Wee1 detected by western blotting using a newly developed antibody (anti-SpWee1) (Lucena et al, 2017) was also slightly stabilized in mts3-1 and skp1-A7 mutants (Fig.…”

“…Because skp1-A7 mutation also caused elevated Wee1 protein levels (Yu et al, 2013), Skp1 might cooperate with Pof1 and Pof3 in the same function. Supporting this assumption, we observed extreme synthetic growth defects in double mutants of skp1-A7 combined with pof3Δ or pof1-6, but not with the other F-box protein mutants examined ( Fig.…”

Wee1 and Cdc25 control morphogenesis, virulence and multistress tolerance of Beauveria bassiana by balancing cell cycle‐required cyclin‐dependent kinase 1 activity

“…The processes of the Cdk1 phosphorylation and dephosphorylation are mediated by the nuclear kinase Wee1 and the dual-specificity phosphatase Cdc25 (Harvey et al, 2005). Wee1 can delay mitosis by inhibiting the Cdk1 phosphorylation (Gould and Nurse, 1989) while Cdc25 promotes entry into mitosis by removing the inhibitory phosphorylation (Gautier et al, 1991;Kumagai and Dunphy, 1991;Yu et al, 2013).…”