MAST/Orbit has a role in microtubule-kinetochore attachment and is essential for chromosome alignment and maintenance of spindle bipolarity
| Autor: | Helder Maiato, Catarina L. Lemos, Mar Carmena, Paula Sampaio, Claudio E. Sunkel, William C. Earnshaw, John Findlay |
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| Přispěvatelé: | Instituto de Biologia Molecular e Celular |
| Jazyk: | angličtina |
| Rok vydání: | 2002 |
| Předmět: |
Spindle
Dynein Mitosis Cell Cycle Proteins Spindle Apparatus Aster (cell biology) Biology Microtubules Article Chromosomes 03 medical and health sciences 0302 clinical medicine Microtubule Animals Drosophila Proteins Kinetochores Metaphase Alleles Cells Cultured 030304 developmental biology RNA Double-Stranded 0303 health sciences Kinetochore MAST microtubules kinetochores spindle Drosophila Dyneins Mast Cell Biology Cell biology Spindle apparatus Microscopy Electron ZW10 Phenotype Mutation Insect Proteins Microtubule-Associated Proteins 030217 neurology & neurosurgery |
| Zdroj: | Repositório Científico de Acesso Aberto de Portugal Repositório Científico de Acesso Aberto de Portugal (RCAAP) instacron:RCAAP The Journal of Cell Biology |
| DOI: | 10.1083/jcb.200201101 |
| Popis: | Multiple asters (MAST)/Orbit is a member of a new family of nonmotor microtubule-associated proteins that has been previously shown to be required for the organization of the mitotic spindle. Here we provide evidence that MAST/Orbit is required for functional kinetochore attachment, chromosome congression, and the maintenance of spindle bipolarity. In vivo analysis of Drosophila mast mutant embryos undergoing early mitotic divisions revealed that chromosomes are unable to reach a stable metaphase alignment and that bipolar spindles collapse as centrosomes move progressively closer toward the cell center and eventually organize into a monopolar configuration. Similarly, soon after depletion of MAST/Orbit in Drosophila S2 cells by double-stranded RNA interference, cells are unable to form a metaphase plate and instead assemble monopolar spindles with chromosomes localized close to the center of the aster. In these cells, kinetochores either fail to achieve end-on attachment or are associated with short microtubules. Remarkably, when microtubule dynamics is suppressed in MAST-depleted cells, chromosomes localize at the periphery of the monopolar aster associated with the plus ends of well-defined microtubule bundles. Furthermore, in these cells, dynein and ZW10 accumulate at kinetochores and fail to transfer to microtubules. However, loss of MAST/Orbit does not affect the kinetochore localization of D-CLIP-190. Together, these results strongly support the conclusion that MAST/Orbit is required for microtubules to form functional attachments to kinetochores and to maintain spindle bipolarity. |
| Databáze: | OpenAIRE |
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