title: The spindle checkpoint requires cyclin-dependent kinase activity.
abstract: The spindle checkpoint prevents anaphase onset until completion of mitotic spindle assembly by restraining activation of the ubiquitin ligase anaphase-promoting complex/cyclosome-Cdc20 (APC/CCdc20). We show that the spindle checkpoint requires mitotic cyclin-dependent kinase (cdk) activity. Inhibiting cdk activity overrides checkpoint-dependent arrest in Xenopus egg extracts and human cells. Following inhibition, the interaction between APC/C and Cdc20 transiently increases while the inhibitory checkpoint protein Mad2 dissociates from Cdc20. Cdk inhibition also overcomes Mad2-induced mitotic arrest. In addition, in vitro cdk1-phosphorylated Cdc20 interacts with Mad2 rather than APC/ C. Thus, cdk activity is required to restrain APC/CCdc20 activation until completion of spindle assembly.
authors.affiliation: Dipartimento di Biologia e Patologia Molecolare e Cellulare L, Califano Medical School, University of Napoli, Federico II, Pansini 5, 80131 Napoli, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: D'Angiolella
authors.forename: Cecilia
authors.initials: C
authors.lastname: Mari
authors.forename: Donatella
authors.initials: D
authors.lastname: Nocera
authors.forename: Linda
authors.initials: L
authors.lastname: Rametti
authors.forename: Domenico
authors.initials: D
authors.lastname: Grieco
mesh_terms: D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D064191:Apc3 Subunit, Anaphase-Promoting Complex-Cyclosome; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins / Q000378:metabolism; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008025:Ligases / Q000378:metabolism; D010063:Ovum / Q000201:enzymology; D008941:Spindle Apparatus / Q000201:enzymology*; D043743:Ubiquitin-Protein Ligase Complexes; D014981:Xenopus
chemical_list: D064191:Apc3 Subunit, Anaphase-Promoting Complex-Cyclosome; C577366:CDC27 protein, human; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins; C577488:CDC20 protein, human; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; D018844:Cyclin-Dependent Kinases; D008025:Ligases