JCB logo
HYBRIGENICS
  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents
Published 28 May 2002. doi:10.1083/jcb.200201101
This Article
Right arrow Full Text
Right arrow PDF (Full Text)
Right arrow Supplemental Material Index
Right arrow Alert me when this article is cited
Right arrow Citation Map
Services
Right arrow Email this article
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new content in the JCB
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via CrossRef
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Maiato, H.
Right arrow Articles by Sunkel, C. E.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Maiato, H.
Right arrow Articles by Sunkel, C. E.
Social Bookmarking
Add to CiteULike   Add to Complore   Add to Connotea   Add to Del.icio.us   Add to Digg   Add to Reddit   Add to Technorati  
What's this?
© The Rockefeller University Press, 0021-9525/2002/5/749 $5.00
The Journal of Cell Biology, Volume 157, Number 5, May 28, 2002 749-760

Article

 MAST/Orbit has a role in microtubule–kinetochore attachment and is essential for chromosome alignment and maintenance of spindle bipolarity

Helder Maiato2,3, Paula Sampaio2, Catarina L. Lemos2, John Findlay4, Mar Carmena3, William C. Earnshaw3 and Claudio E. Sunkel1,2

1 Instituto de Ciências Biomédicas de Abel Salazar, Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180 Porto, Portugal
2 Laboratório de Genética Molecular, Instituto de Biologia Molecular e Celular, Universidade do Porto, 4150-180 Porto, Portugal
3 Chromosome Structure Group, Wellcome Trust Centre for Cell Biology
4 Biological Sciences Electron Microscope Facility, Institute of Cell and Molecular Biology, University of Edinburgh, Scotland, UK

Address correspondence to Claudio E. Sunkel, Instituto de Biologia Molecular e Celular, Universidade do Porto, Rua do Campo Alegre 823, 4150-180 Porto, Portugal. Tel.: 351-22-607-4900. Fax: 351-22-609-9157. E-mail: cesunkel{at}ibmc.up.pt

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.

Key Words: MAST; microtubules; kinetochores; spindle; Drosophila


Add to CiteULike CiteULike   Add to Complore Complore   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us   Add to Digg Digg   Add to Reddit Reddit   Add to Technorati Technorati    What's this?


This article has been cited by other articles:



  Home | Help | Feedback | Subscriptions | Archive | Search | Table of Contents