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Cell. 2006 Nov 17;127(4):759-73.

Role for the PP2A/B56delta phosphatase in regulating 14-3-3 release from Cdc25 to control mitosis.

Author information

1
Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC 27710, USA.

Abstract

DNA-responsive checkpoints prevent cell-cycle progression following DNA damage or replication inhibition. The mitotic activator Cdc25 is suppressed by checkpoints through inhibitory phosphorylation at Ser287 (Xenopus numbering) and docking of 14-3-3. Ser287 phosphorylation is a major locus of G2/M checkpoint control, although several checkpoint-independent kinases can phosphorylate this site. We reported previously that mitotic entry requires 14-3-3 removal and Ser287 dephosphorylation. We show here that DNA-responsive checkpoints also activate PP2A/B56delta phosphatase complexes to dephosphorylate Cdc25 at a site distinct from Ser287 (T138), the phosphorylation of which is required for 14-3-3 release. However, phosphorylation of T138 is not sufficient for 14-3-3 release from Cdc25. Our data suggest that creation of a 14-3-3 "sink," consisting of phosphorylated 14-3-3 binding intermediate filament proteins, including keratins, coupled with reduced Cdc25-14-3-3 affinity, contribute to Cdc25 activation. These observations identify PP2A/B56delta as a central checkpoint effector and suggest a mechanism for controlling 14-3-3 interactions to promote mitosis.

PMID:
17110335
PMCID:
PMC2789796
DOI:
10.1016/j.cell.2006.10.035
[Indexed for MEDLINE]
Free PMC Article

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