Amphiastral Mitotic Spindle Assembly in Vertebrate Cells Lacking Centrosomes
| Autor: | Jessica E. Hornick, Christopher C. Mader, Edward H. Hinchcliffe, Kevin T. Vaughan, Sidney L. Shaw, Cydney C. Bagne, Emily K. Tribble |
|---|---|
| Rok vydání: | 2011 |
| Předmět: |
Microsurgery
Centriole Nuclear Envelope Dynein Kinesins Mitosis Spindle Apparatus Biology Microtubules Article General Biochemistry Genetics and Molecular Biology Cell Line 03 medical and health sciences Chlorocebus aethiops Animals Antigens Centrioles 030304 developmental biology Centrosome 0303 health sciences Agricultural and Biological Sciences(all) Biochemistry Genetics and Molecular Biology(all) Cell Cycle 030302 biochemistry & molecular biology Dyneins Microtubule organizing center Dynactin Complex Chromosomes Mammalian Cell biology Spindle apparatus ran GTP-Binding Protein Vertebrates Dynactin General Agricultural and Biological Sciences Microtubule-Associated Proteins Multipolar spindles Microtubule-Organizing Center |
| Zdroj: | Current Biology. 21(7):598-605 |
| ISSN: | 0960-9822 |
| DOI: | 10.1016/j.cub.2011.02.049 |
| Popis: | SummaryThe role of centrosomes and centrioles during mitotic spindle assembly in vertebrates remains controversial. In cell-free extracts and experimentally derived acentrosomal cells, randomly oriented microtubules (MTs) self-organize around mitotic chromosomes and assemble anastral spindles [1–3]. However, vertebrate somatic cells normally assemble a connected pair of polarized, astral MT arrays—termed an amphiaster (“a star on both sides” [4])—that is formed by the splitting and separation of the microtubule-organizing center (MTOC) well before nuclear envelope breakdown (NEB) [5]. Whether amphiaster formation requires splitting of duplicated centrosomes is not known. We found that when centrosomes were removed from living vertebrate cells early in their cell cycle, an acentriolar MTOC reassembled, and, prior to NEB, a functional amphiastral spindle formed. Cytoplasmic dynein, dynactin, and pericentrin are all recruited to the interphase aMTOC, and the activity of kinesin-5 is needed for amphiaster formation. Mitosis proceeded on time and these karyoplasts divided in two. However, ∼35% of aMTOCs failed to split and separate before NEB, and these entered mitosis with persistent monastral spindles. Chromatin-associated RAN-GTP—the small GTPase Ran in its GTP bound state—could not restore bipolarity to monastral spindles, and these cells exited mitosis as single daughters. Our data reveal the novel finding that MTOC separation and amphiaster formation does not absolutely require the centrosome, but, in its absence, the fidelity of bipolar spindle assembly is highly compromised. |
| Databáze: | OpenAIRE |
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