title: Self- and actin-templated assembly of Mammalian septins.
abstract: Septins are polymerizing GTPases required for cytokinesis and cortical organization. The principles by which they are targeted to, and assemble at, specific cell regions are unknown. We show that septins in mammalian cells switch between a linear organization along actin bundles and cytoplasmic rings, approximately 0.6 microm in diameter. A recombinant septin complex self-assembles into rings resembling those in cells. Linear organization along actin bundles was reconstituted by adding an adaptor protein, anillin. Perturbation of septin organization in cells by expression of a septin-interacting fragment of anillin or by septin depletion via siRNA causes loss of actin bundles. We conclude that septins alone self-assemble into rings, that adaptor proteins recruit septins to actin bundles, and that septins help organize these bundles.
authors.affiliation: Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA. makoto_kinoshita@hms.harvard.edu
authors.forename: Makoto
authors.initials: M
authors.lastname: Kinoshita
authors.forename: Christine M
authors.initials: CM
authors.lastname: Field
authors.forename: Margaret L
authors.initials: ML
authors.lastname: Coughlin
authors.forename: Aaron F
authors.initials: AF
authors.lastname: Straight
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Mitchison
mesh_terms: D016475:3T3 Cells; D008841:Actin Cytoskeleton / Q000378:metabolism*; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001665:Binding Sites / Q000502:physiology; D001798:Blood Proteins / Q000235:genetics / Q000378:metabolism; D002352:Carrier Proteins; D002451:Cell Compartmentation / Q000502:physiology*; D003285:Contractile Proteins / Q000378:metabolism; D003598:Cytoskeletal Proteins; D005057:Eukaryotic Cells / Q000166:cytology / Q000378:metabolism*; D020549:GTP Phosphohydrolase Activators; D020558:GTP Phosphohydrolases; D020555:GTP-Binding Protein Regulators; D019204:GTP-Binding Proteins / Q000172:deficiency* / Q000235:genetics*; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D008164:Luminescent Proteins; D051379:Mice; D017434:Protein Structure, Tertiary / Q000502:physiology; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; D058112:Septins; D020764:cdc42 GTP-Binding Protein; D020741:rho GTP-Binding Proteins
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D001798:Blood Proteins; C422984:CDC42EP2 protein, human; C484093:CDC42EP3 protein, human; C422985:CDC42EP4 protein, human; C484094:CDC42EP5 protein, human; D002352:Carrier Proteins; C484092:Cdc42ep5 protein, mouse; D003285:Contractile Proteins; D003598:Cytoskeletal Proteins; D020549:GTP Phosphohydrolase Activators; D020555:GTP-Binding Protein Regulators; D008164:Luminescent Proteins; D016601:RNA-Binding Proteins; D011993:Recombinant Fusion Proteins; C095886:anillin; D049452:Green Fluorescent Proteins; C075598:CDC42EP1 protein, human; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; C436485:SEPTIN6 protein, human; C486672:Sept6 protein, mouse; D058112:Septins; D020764:cdc42 GTP-Binding Protein; D020741:rho GTP-Binding Proteins