Plk1 regulates activation of the anaphase promoting complex by phosphorylating and triggering SCFbetaTrCP-dependent destruction of the APC Inhibitor Emi1.
Progression through mitosis requires activation of cyclin B/Cdk1 and its downstream targets, including Polo-like kinase and the anaphase-promoting complex (APC), the ubiquitin ligase directing degradation of cyclins A and B. Recent evidence shows that APC activation requires destruction of the APC inhibitor Emi1. In prophase, phosphorylation of Emi1 generates a D-pS-G-X-X-pS degron to recruit the SCF(betaTrCP) ubiquitin ligase, causing Emi1 destruction and allowing progression beyond prometaphase, but the kinases directing this phosphorylation remain undefined. We show here that the polo-like kinase Plk1 is strictly required for Emi1 destruction and that overexpression of Plk1 is sufficient to trigger Emi1 destruction. Plk1 stimulates Emi1 phosphorylation, betaTrCP binding, and ubiquitination in vitro and cyclin B/Cdk1 enhances these effects. Plk1 binds to Emi1 in mitosis and the two proteins colocalize on the mitotic spindle poles, suggesting that Plk1 may spatially control Emi1 destruction. These data support the hypothesis that Plk1 activates the APC by directing the SCF-dependent destruction of Emi1 in prophase.
Department of Pathology, Stanford University School of Medicine, Palo Alto, CA 94305, USA.
David V
DV
Hansen
Alexander V
AV
Loktev
Kenneth H
KH
Ban
Peter K
PK
Jackson
D000705:Anaphase; D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D016764:Cell Polarity; D004789:Enzyme Activation; D044783:F-Box Proteins; D006801:Humans; D008938:Mitosis; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D044843:SKP Cullin F-Box Protein Ligases / Q000378:metabolism*; D008941:Spindle Apparatus / Q000378:metabolism; D013997:Time Factors; D025801:Ubiquitin / Q000378:metabolism; D043743:Ubiquitin-Protein Ligase Complexes / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D029867:Xenopus Proteins; D014982:Xenopus laevis; D000097869:Polo-Like Kinase 1
D064173:Anaphase-Promoting Complex-Cyclosome; D018797:Cell Cycle Proteins; D044783:F-Box Proteins; D010768:Phosphoserine; D011494:Protein Kinases; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D044843:SKP Cullin F-Box Protein Ligases; D025801:Ubiquitin; D043743:Ubiquitin-Protein Ligase Complexes; D029867:Xenopus Proteins; D000097869:Polo-Like Kinase 1; C429107:FBXO5 protein, Xenopus; C498960:FBXO5 protein, human