Cyclin A2-cyclin-dependent kinase 2 cooperates with the PLK1-SCFbeta-TrCP1-EMI1-anaphase-promoting complex/cyclosome axis to promote genome reduplication in the absence of mitosis.
Limiting genome replication to once per cell cycle is vital for maintaining genome stability. Inhibition of cyclin-dependent kinase 1 (CDK1) with the specific inhibitor RO3306 is sufficient to trigger multiple rounds of genome reduplication. We demonstrated that although anaphase-promoting complex/cyclosome (APC/C) remained inactive during the initial G(2) arrest, it was activated upon prolonged inhibition of CDK1. Using cellular biosensors and live-cell imaging, we provide direct evidence that genome reduplication was associated with oscillation of APC/C activity and nuclear-cytoplasmic shuttling of CDC6 even in the absence of mitosis at the single-cell level. Genome reduplication was abolished by ectopic expression of EMI1 or depletion of CDC20 or CDH1, suggesting the critical role of the EMI1-APC/C axis. In support of this, degradation of EMI1 itself and genome reduplication were delayed after downregulation of PLK1 and beta-TrCP1. In the absence of CDK1 activity, activation of APC/C and genome reduplication was dependent on cyclin A2 and CDK2. Genome reduplication was then promoted by a combination of APC/C-dependent destruction of geminin (thus releasing CDT1), accumulation of cyclin E2-CDK2, and CDC6. Collectively, these results underscore the crucial role of cyclin A2-CDK2 in regulating the PLK1-SCF(beta-TrCP1)-EMI1-APC/C axis and CDC6 to trigger genome reduplication after the activity of CDK1 is suppressed.
Ma
Hoi Tang
HT
Department of Biochemistry, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong. rycpoon@ust.hk.
Tsang
Yiu Huen
YH
Marxer
Miriam
M
Poon
Randy Y C
RY
D064173:Anaphase-Promoting Complex-Cyclosome; D000818:Animals; D016203:CDC2 Protein Kinase / Q000037:antagonists & inhibitors; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D056751:Cyclin A2 / Q000235:genetics / Q000378:metabolism*; D051357:Cyclin-Dependent Kinase 2 / Q000235:genetics / Q000378:metabolism*; D004261:DNA Replication; D044783:F-Box Proteins / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008938:Mitosis / Q000502:physiology; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D011804:Quinolines / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D044843:SKP Cullin F-Box Protein Ligases / Q000235:genetics / Q000378:metabolism*; D013844:Thiazoles / Q000378:metabolism; D043743:Ubiquitin-Protein Ligase Complexes / Q000235:genetics / Q000378:metabolism*; D000097869:Polo-Like Kinase 1
D064173:Anaphase-Promoting Complex-Cyclosome; D016203:CDC2 Protein Kinase; D018797:Cell Cycle Proteins; D056751:Cyclin A2; D051357:Cyclin-Dependent Kinase 2; D044783:F-Box Proteins; D009687:Nuclear Proteins; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D011804:Quinolines; D011993:Recombinant Fusion Proteins; D044843:SKP Cullin F-Box Protein Ligases; D013844:Thiazoles; D043743:Ubiquitin-Protein Ligase Complexes; D000097869:Polo-Like Kinase 1; C103706:CDC6 protein, human; C498960:FBXO5 protein, human; C512984:RO 3306