title: Cdk1-dependent mitotic enrichment of cortical myosin II promotes cell rounding against confinement.
abstract: Actomyosin-dependent mitotic rounding occurs in both cell culture and tissue, where it is involved in cell positioning and epithelial organization. How actomyosin is regulated to mediate mitotic rounding is not well understood. Here we characterize the mechanics of single mitotic cells while imaging actomyosin recruitment to the cell cortex. At mitotic onset, the assembly of a uniform DIAPH1-dependent F-actin cortex coincides with initial rounding. Thereafter, cortical enrichment of F-actin remains stable while myosin II progressively accumulates at the cortex, and the amount of myosin at the cortex correlates with intracellular pressure. Whereas F-actin provides only short-term (<10 s) resistance to mechanical deformation, myosin sustains intracellular pressure for a longer duration (>60 s). Our data suggest that progressive accumulation of myosin II to the mitotic cell cortex probably requires the Cdk1 activation of both p21-activated kinases, which inhibit myosin recruitment, and of Rho kinase, which stimulates myosin recruitment to the cortex.
authors.affiliation: Eidgenössische Technische Hochschule (ETH) Zurich, Department of Biosystems Science and Engineering, 4058 Basel, Switzerland.
authors.forename: Subramanian P
authors.initials: SP
authors.lastname: Ramanathan
authors.affiliation: Eidgenössische Technische Hochschule (ETH) Zurich, Department of Biosystems Science and Engineering, 4058 Basel, Switzerland.
authors.forename: Jonne
authors.initials: J
authors.lastname: Helenius
authors.affiliation: 1] Eidgenössische Technische Hochschule (ETH) Zurich, Department of Biosystems Science and Engineering, 4058 Basel, Switzerland [2] Massachusetts Institute of Technology (MIT), Department of Chemical Engineering, Cambridge, Massachusetts 02139, USA [3] The David H. Koch Institute for Integrative Cancer Research at MIT, Cambridge, Massachusetts 02139, USA.
authors.forename: Martin P
authors.initials: MP
authors.lastname: Stewart
authors.affiliation: Eidgenössische Technische Hochschule (ETH) Zurich, Department of Biosystems Science and Engineering, 4058 Basel, Switzerland.
authors.forename: Cedric J
authors.initials: CJ
authors.lastname: Cattin
authors.affiliation: Max Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany.
authors.forename: Anthony A
authors.initials: AA
authors.lastname: Hyman
authors.affiliation: Eidgenössische Technische Hochschule (ETH) Zurich, Department of Biosystems Science and Engineering, 4058 Basel, Switzerland.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Muller
mesh_terms: D000199:Actins / Q000378:metabolism; D000205:Actomyosin / Q000378:metabolism; D016203:CDC2 Protein Kinase / Q000378:metabolism*; D003545:Cysteine / Q000031:analogs & derivatives / Q000494:pharmacology; D005326:Fetal Proteins / Q000378:metabolism; D000080865:Formins; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D042541:Intracellular Space / Q000187:drug effects / Q000378:metabolism; D008840:Microfilament Proteins / Q000378:metabolism; D018625:Microscopy, Atomic Force; D008938:Mitosis / Q000187:drug effects; D008954:Models, Biological; D024462:Myosin Type II / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D011312:Pressure; D013997:Time Factors; D020741:rho GTP-Binding Proteins / Q000378:metabolism; D054460:rho-Associated Kinases / Q000378:metabolism
chemical_list: D000199:Actins; D005326:Fetal Proteins; D000080865:Formins; D008840:Microfilament Proteins; D009687:Nuclear Proteins; D049452:Green Fluorescent Proteins; C003724:3-tritylthio-L-alanine; D000205:Actomyosin; D054460:rho-Associated Kinases; D016203:CDC2 Protein Kinase; D024462:Myosin Type II; D020741:rho GTP-Binding Proteins; D003545:Cysteine