In all eukaryotic cells, entry into mitosis is controlled by the Cyclin-dependent kinase, Cdc2. Cdc2/Cyclin B complexes are controlled by the inhibitory kinases, Myt1 and Wee1 and by the activating phosphatase, Cdc25. Although a number of Cdc25 and Myt1/Wee1-regulatory pathways have been identified, how these pathways are interconnected and which upstream modulators impinge on these pathways is not yet entirely clear. To understand how physiological stimuli and checkpoint control pathways regulate the G2/M transition, it is essential that we understand the causal connections and regulatory interplays between these diverse regulators. This proposal employs the powerful in vitro reconstitution system for mitotic entry provided by Xenopus egg extracts to investigate Cdc25 and Wee1 regulation. In this proposal we address several outstanding issues in G21M regulation, including the mechanism by which Cdc25 is activated at mitosis through removal of bound 14-3-3 proteins, whether Cdc25-directed activating phosphatases may be cell cycle regulated and how different isoforms of Cdc25 may be differentially regulated. We also investigate several candidate regulators of Wee1, including the kinase PIx and the methyltransferase, Hsl7. Our long-term objective is to obtain a mechanistic understanding of the molecular events that control entry into mitosis.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
1R01GM067225-01A1
Application #
6688033
Study Section
Cell Development and Function Integrated Review Group (CDF)
Program Officer
Zatz, Marion M
Project Start
2003-09-01
Project End
2007-08-31
Budget Start
2003-09-01
Budget End
2004-08-31
Support Year
1
Fiscal Year
2003
Total Cost
$261,800
Indirect Cost
Name
Duke University
Department
Pharmacology
Type
Schools of Medicine
DUNS #
044387793
City
Durham
State
NC
Country
United States
Zip Code
27705
Tang, Wanli; Wu, Judy Qiju; Chen, Chen et al. (2010) Emi2-mediated inhibition of E2-substrate ubiquitin transfer by the anaphase-promoting complex/cyclosome through a D-box-independent mechanism. Mol Biol Cell 21:2589-97
Wu, Judy Qiju; Guo, Jessie Yanxiang; Tang, Wanli et al. (2009) PP1-mediated dephosphorylation of phosphoproteins at mitotic exit is controlled by inhibitor-1 and PP1 phosphorylation. Nat Cell Biol 11:644-51
Tang, Wanli; Wu, Judy Qiju; Guo, Yanxiang et al. (2008) Cdc2 and Mos regulate Emi2 stability to promote the meiosis I-meiosis II transition. Mol Biol Cell 19:3536-43
Guo, Jessie Yanxiang; Yamada, Ayumi; Kajino, Taisuke et al. (2008) Aven-dependent activation of ATM following DNA damage. Curr Biol 18:933-42
Wu, Qiju; Guo, Yanxiang; Yamada, Ayumi et al. (2007) A role for Cdc2- and PP2A-mediated regulation of Emi2 in the maintenance of CSF arrest. Curr Biol 17:213-24
Wu, Judy Qiju; Hansen, David V; Guo, Yanxiang et al. (2007) Control of Emi2 activity and stability through Mos-mediated recruitment of PP2A. Proc Natl Acad Sci U S A 104:16564-9
Zhu, Wenge; Ukomadu, Chinweike; Jha, Sudhakar et al. (2007) Mcm10 and And-1/CTF4 recruit DNA polymerase alpha to chromatin for initiation of DNA replication. Genes Dev 21:2288-99
Margolis, Seth S; Perry, Jennifer A; Forester, Craig M et al. (2006) Role for the PP2A/B56delta phosphatase in regulating 14-3-3 release from Cdc25 to control mitosis. Cell 127:759-73
Margolis, Seth S; Perry, Jennifer A; Weitzel, Douglas H et al. (2006) A role for PP1 in the Cdc2/Cyclin B-mediated positive feedback activation of Cdc25. Mol Biol Cell 17:1779-89
Casaletto, Jessica B; Nutt, Leta K; Wu, Qiju et al. (2005) Inhibition of the anaphase-promoting complex by the Xnf7 ubiquitin ligase. J Cell Biol 169:61-71

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