APC/C(Cdc20) controls the ubiquitin-mediated degradation of p21 in prometaphase.
During the G1/S transition, p21 proteolysis is mediated by Skp2; however, p21 reaccumulates in G2 and is degraded again in prometaphase. How p21 degradation is controlled in mitosis remains unexplored. We found that Cdc20 (an activator of the ubiquitin ligase APC/C) binds p21 in cultured cells and identified a D box motif in p21 necessary for APC/C(Cdc20)-mediated ubiquitylation of p21. Overexpression of Cdc20 or Skp2 destabilized wild-type p21; however, only Skp2, but not Cdc20, was able to destabilize a p21(D box) mutant. Silencing of Cdc20 induced an accumulation of p21, increased the fraction of p21 bound to Cdk1, and inhibited Cdk1 activity in p21(+/+) prometaphase cells, but not in p21(-/-) cells. Thus, in prometaphase Cdc20 positively regulates Cdk1 by mediating the degradation of p21. We propose that the APC/C(Cdc20)-mediated degradation of p21 contributes to the full activation of Cdk1 necessary for mitotic events and prevents mitotic slippage during spindle checkpoint activation.
Department of Pathology, NYU Cancer Institute, New York University School of Medicine, 550 First Avenue MSB 599, New York, NY 10016, USA.
Virginia
V
Amador
Sheng
S
Ge
Patricia G
PG
Santamaría
Daniele
D
Guardavaccaro
Michele
M
Pagano
D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D016203:CDC2 Protein Kinase / Q000235:genetics / Q000378:metabolism; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins / Q000502:physiology*; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism*; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000235:genetics / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000378:metabolism; D005909:Glioblastoma / Q000378:metabolism / Q000473:pathology; D006801:Humans; D015151:Immunoblotting; D047468:Immunoprecipitation; D008168:Lung; D051379:Mice; D018345:Mice, Knockout; D016297:Mutagenesis, Site-Directed; D049468:Prometaphase; D044786:S-Phase Kinase-Associated Proteins / Q000235:genetics / Q000502:physiology; D025801:Ubiquitin / Q000378:metabolism; D043743:Ubiquitin-Protein Ligase Complexes / Q000502:physiology*; D044767:Ubiquitin-Protein Ligases / Q000037:antagonists & inhibitors*
D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D004791:Enzyme Inhibitors; D044786:S-Phase Kinase-Associated Proteins; D025801:Ubiquitin; D050760:Cyclin-Dependent Kinase Inhibitor p27; C577488:CDC20 protein, human; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D044767:Ubiquitin-Protein Ligases; D016203:CDC2 Protein Kinase