title: The contractile ring coordinates curvature-dependent septum assembly during fission yeast cytokinesis.
abstract: The functions of the actin-myosin-based contractile ring in cytokinesis remain to be elucidated. Recent findings show that in the fission yeast Schizosaccharomyces pombe, cleavage furrow ingression is driven by polymerization of cell wall fibers outside the plasma membrane, not by the contractile ring. Here we show that one function of the ring is to spatially coordinate septum cell wall assembly. We develop an improved method for live-cell imaging of the division apparatus by orienting the rod-shaped cells vertically using microfabricated wells. We observe that the septum hole and ring are circular and centered in wild-type cells and that in the absence of a functional ring, the septum continues to ingress but in a disorganized and asymmetric manner. By manipulating the cleavage furrow into different shapes, we show that the ring promotes local septum growth in a curvature-dependent manner, allowing even a misshapen septum to grow into a more regular shape. This curvature-dependent growth suggests a model in which contractile forces of the ring shape the septum cell wall by stimulating the cell wall machinery in a mechanosensitive manner. Mechanical regulation of the cell wall assembly may have general relevance to the morphogenesis of walled cells.
authors.affiliation: Department of Microbiology and Immunology, Columbia University College of Physicians and Surgeons, New York, NY 10032.
authors.forename: Zhou
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: Department of Microbiology and Immunology, Columbia University College of Physicians and Surgeons, New York, NY 10032.
authors.forename: Emilia Laura
authors.initials: EL
authors.lastname: Munteanu
authors.affiliation: Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Jun
authors.initials: J
authors.lastname: He
authors.affiliation: Department of Bioengineering, Stanford University, Stanford, CA 94305.
authors.forename: Tristan
authors.initials: T
authors.lastname: Ursell
authors.affiliation: Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.
authors.forename: Mark
authors.initials: M
authors.lastname: Bathe
authors.affiliation: Department of Bioengineering, Stanford University, Stanford, CA 94305 Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA 94305.
authors.forename: Kerwyn Casey
authors.initials: KC
authors.lastname: Huang
authors.affiliation: Department of Microbiology and Immunology, Columbia University College of Physicians and Surgeons, New York, NY 10032 fc99@columbia.edu.
authors.forename: Fred
authors.initials: F
authors.lastname: Chang
mesh_terms: D000199:Actins / Q000737:chemistry; D002462:Cell Membrane / Q000502:physiology; D002473:Cell Wall / Q000502:physiology*; D048749:Cytokinesis / Q000502:physiology*; D009024:Morphogenesis; D058105:Polymerization; D012568:Schizosaccharomyces / Q000166:cytology*
chemical_list: D000199:Actins