title: Cdk1 is essential for mammalian cyclosome/APC regulation.
abstract: The cyclosome/APC (anaphase-promoting complex), the major component of cell-cycle-specific ubiquitin-mediated proteolysis of mitotic cyclins and of other cell cycle proteins, is essential for sister chromatid separation and for exit from mitosis. Cyclosome activity and substrate specificity are modulated by phosphorylation and by transient interactions with Fizzy/cdc20 (Fzy) and Fizzy-related/Hct1/Cdh1 (Fzr). This regulation has been studied so far in Drosophila embryos, in yeast, and in cell-free extracts in vitro. Studying cyclosome regulation in mammalian cells in vivo we found that both Fzr overexpression and Cdk1 inhibition can override the prometaphase checkpoint. We further show that Fzr activation of the cyclosome is negatively regulated by Cdk1. Finally, we show that the mammalian cdc14 phosphatase, like its budding yeast homologue, plays a role in cyclosome pathway regulation. These results suggest that Cdk1 is essential for coupling various activities of the cyclosome and in particular for preventing Fzr from short-circuiting the spindle pole checkpoint. Cdk1-cyclin B is thus an inhibitor, activator, and substrate of the cyclosome.
authors.affiliation: Department of Genetics, The Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.
authors.forename: T
authors.initials: T
authors.lastname: Listovsky
authors.forename: A
authors.initials: A
authors.lastname: Zor
authors.forename: A
authors.initials: A
authors.lastname: Laronne
authors.forename: M
authors.initials: M
authors.lastname: Brandeis
mesh_terms: D016475:3T3 Cells; D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D016203:CDC2 Protein Kinase / Q000235:genetics / Q000378:metabolism*; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation; D006801:Humans; D008025:Ligases / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D015398:Signal Transduction; D043743:Ubiquitin-Protein Ligase Complexes; D044767:Ubiquitin-Protein Ligases
chemical_list: D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins; C577488:CDC20 protein, human; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D044767:Ubiquitin-Protein Ligases; D016203:CDC2 Protein Kinase; D008025:Ligases