Lee, Joon and Kumagai, Akiko and Dunphy, William G. (2001) Positive regulation of Wee1 by Chk1 and 14-3-3 proteins. Molecular Biology of the Cell, 12 (3). pp. 551-563. ISSN 1059-1524 http://resolver.caltech.edu/CaltechAUTHORS:LEEmbc01
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Wee1 inactivates the Cdc2-cyclin B complex during interphase by phosphorylating Cdc2 on Tyr-15. The activity of Wee1 is highly regulated during the cell cycle. In frog egg extracts, it has been established previously that Xenopus Wee1 (Xwee1) is present in a hypophosphorylated, active form during interphase and undergoes down-regulation by extensive phosphorylation at M-phase. We report that Xwee1 is also regulated by association with 14-3-3 proteins. Binding of 14-3-3 to Xwee1 occurs during interphase, but not M-phase, and requires phosphorylation of Xwee1 on Ser-549. A mutant of Xwee1 (S549A) that cannot bind 14-3-3 is substantially less active than wild-type Xwee1 in its ability to phosphorylate Cdc2. This mutation also affects the intranuclear distribution of Xwee1. In cell-free kinase assays, Xchk1 phosphorylates Xwee1 on Ser-549. The results of experiments in which Xwee1, Xchk1, or both were immunodepleted from Xenopus egg extracts suggested that these two enzymes are involved in a common pathway in the DNA replication checkpoint response. Replacement of endogenous Xwee1 with recombinant Xwee1-S549A in egg extracts attenuated the cell cycle delay induced by addition of excess recombinant Xchk1. Taken together, these results suggest that Xchk1 and 14-3-3 proteins act together as positive regulators of Xwee1.
|Additional Information:||© 2001 by The American Society for Cell Biology. Submitted September 6, 2000; revised November 29, 2000; accepted January 16, 2000. We are thankful to our colleagues in the Dunphy lab for helpful comments on this work. We are indebted to Charlotte Pham for assistance with plasmid manipulation. This work was supported in part by a grant from the National Institutes of Health. J.L. is an associate and W.G.D. is an investigator of the Howard Hughes Medical Institute.|
|Subject Keywords:||DNA-DAMAGE CHECKPOINT; CELL-CYCLE REGULATION; XENOPUS EGG EXTRACTS; CDC25 PHOSPHATASE; MITOTIC INHIBITOR; TYROSINE KINASE; INDUCER CDC25; PHOSPHORYLATION; NUCLEAR; BINDING|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Lindsay Cleary|
|Deposited On:||21 Aug 2006|
|Last Modified:||26 Dec 2012 08:59|
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