title: Mitotic trigger waves and the spatial coordination of the Xenopus cell cycle.
abstract: Despite the large size of the Xenopus laevis egg (approximately 1.2 mm diameter), a fertilized egg rapidly proceeds through mitosis in a spatially coordinated fashion. Mitosis is initiated by a bistable system of regulatory proteins centred on Cdk1 (refs 1, 2), raising the possibility that this spatial coordination could be achieved through trigger waves of Cdk1 activity. Using an extract system that performs cell cycles in vitro, here we show that mitosis does spread through Xenopus cytoplasm via trigger waves, propagating at a linear speed of approximately 60 µm min(-1). Perturbing the feedback loops that give rise to the bistability of Cdk1 changes the speed and dynamics of the waves. Time-lapse imaging of intact eggs argues that trigger waves of Cdk1 activation are responsible for surface contraction waves, ripples in the cell cortex that precede cytokinesis. These findings indicate that Cdk1 trigger waves help ensure the spatiotemporal coordination of mitosis in large eggs. Trigger waves may be an important general mechanism for coordinating biochemical events over large distances.
authors.affiliation: Department of Chemical and Systems Biology, Stanford University School of Medicine, Stanford, California 94305-5174, USA. jbchang@stanford.edu
authors.forename: Jeremy B
authors.initials: JB
authors.lastname: Chang
authors.forename: James E
authors.initials: JE
authors.lastname: Ferrell
mesh_terms: D000200:Action Potentials; D000818:Animals; D016203:CDC2 Protein Kinase / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000037:antagonists & inhibitors; D002457:Cell Extracts; D003593:Cytoplasm / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D004058:Diffusion; D004789:Enzyme Activation; D008938:Mitosis / Q000187:drug effects; D009068:Movement / Q000187:drug effects; D010063:Ovum / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D011743:Pyrimidines / Q000494:pharmacology; D029867:Xenopus Proteins / Q000037:antagonists & inhibitors; D014982:Xenopus laevis; D015053:Zygote / Q000166:cytology / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D002457:Cell Extracts; C440869:PD 0166285; D011743:Pyrimidines; D029867:Xenopus Proteins; C095970:MYT1 kinase, Xenopus; C530005:WEE1 protein, Xenopus; D011505:Protein-Tyrosine Kinases; D017346:Protein Serine-Threonine Kinases; D016203:CDC2 Protein Kinase