期刊
JOURNAL OF CELL SCIENCE
卷 124, 期 10, 页码 1664-1671出版社
COMPANY BIOLOGISTS LTD
DOI: 10.1242/jcs.081216
关键词
Mitosis; Spindle assembly checkpoint; Mad2; Dynein; RZZ
类别
资金
- Centre National de la Recherche Scientifique (CNRS)
- Agence Nationale de la Recherche [ANR-08-BLAN-0006-01]
- Association pour la Recherche sur le Cancer (ARC)
- Ministere de l'Enseignement superieur et de la Recherche
- Fondation pour la Recherche Medicale
- Agence Nationale de la Recherche (ANR) [ANR-08-BLAN-0006] Funding Source: Agence Nationale de la Recherche (ANR)
Unattached kinetochores generate an anaphase inhibitor, through the spindle assembly checkpoint (SAC), that allows cells more time to establish proper kinetochore-microtubule (K-MT) linkages and thus avoid aneuploidy. Mad1 is the receptor for Mad2 at kinetochores, where it catalyzes the formation of Mad2-Cdc20 complexes, an essential part of the anaphase inhibitor, but whether it has any other mitotic function is unknown. We have generated a mad1-null mutation in Drosophila. This mutant is SAC defective and Mad2 is no longer localized to either nuclear envelope or kinetochores, but it displays normal basal mitotic timing. Unlike mad2 mutants, which have relatively normal mitoses, mad1 anaphases show high frequencies of lagging chromatids, at least some of which are caused by persistent merotelic linkages. A transgene expressing GFP-Mad1 rescues both the SAC and the anaphase defects. In an attempt to separate the SAC function from the mitotic function, we made a mad1 transgene with a mutated Mad2-binding domain. Surprisingly, this transgene failed to complement the anaphase phenotype. Thus, Mad1 has activity promoting proper K-MT attachments in addition to its checkpoint function. This activity does not require the presence of Mad2, but it does depend in some unknown way on key residues in the Mad2-binding domain of Mad1.
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