title: Cell-sized spherical confinement induces the spontaneous formation of contractile actomyosin rings in vitro.
abstract: During cell division, many animal cells transform into a spherical shape and assemble a contractile ring composed of actin filaments and myosin motors at the equator to separate the cell body into two. Although actomyosin regulatory proteins are spatio-temporally controlled during cytokinesis, the direct contribution of cell shape and actomyosin activity to the contractile ring assembly remains unclear. Here, we demonstrated in vitro that actin polymerization inside cell-sized spherical droplets induced the spontaneous formation of single ring-shaped actin bundles in the presence of bundling factors. Despite a lack of spatial regulatory signals, the rings always assembled at the equator to minimize the elastic energy of the bundles. Myosin promoted ring formation by the dynamic remodelling of actin networks, and an increase in the effective concentration of myosin triggered ring contraction. These results will help us understand how animal cells coordinate cell shape and actomyosin activities to direct cytokinesis.
authors: Department of Physics, Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku Tokyo 169-8555, Japan.
authors: Makito
authors: M
authors: Miyazaki
authors: Department of Physics, Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku Tokyo 169-8555, Japan.
authors: Masataka
authors: M
authors: Chiba
authors: Department of Physics, Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku Tokyo 169-8555, Japan.
authors: Hiroki
authors: H
authors: Eguchi
authors: Department of Physics, Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku Tokyo 169-8555, Japan.
authors: Takashi
authors: T
authors: Ohki
authors: 1] Department of Physics, Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku Tokyo 169-8555, Japan [2] Waseda Bioscience Research Institute in Singapore (WABIOS), 11 Biopolis Way, #05-01/02 Helios Singapore 138667, Singapore.
authors: Shin'ichi
authors: S
authors: Ishiwata
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism; D000199:Actins / Q000378:metabolism*; D000205:Actomyosin / Q000378:metabolism*; D000818:Animals; D002455:Cell Division / Q000502:physiology*; D048430:Cell Shape / Q000502:physiology*; D048749:Cytokinesis / Q000502:physiology*; D024462:Myosin Type II / Q000378:metabolism; D024701:Myosin Type V / Q000378:metabolism
chemical_list: D000199:Actins; D000205:Actomyosin; D024462:Myosin Type II; D024701:Myosin Type V