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Spatial regulation of the spindle assembly checkpoint and anaphase‐promoting complex in A spergillus nidulans
Author(s) -
Edgerton Heather,
Paolillo Vitoria,
Oakley Berl R.
Publication year - 2015
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12871
Subject(s) - biology , telophase , microbiology and biotechnology , mitosis , spindle checkpoint , anaphase , spindle pole body , kinetochore , mitotic exit , spindle apparatus , cell cycle , nucleoplasm , cell division , genetics , cell , cytoplasm , nucleolus , chromosome , gene
Summary The spindle assembly checkpoint ( SAC ) plays a critical role in preventing mitotic errors by inhibiting anaphase until all kinetochores are correctly attached to spindle microtubules. In spite of the economic and medical importance of filamentous fungi, relatively little is known about the behavior of SAC proteins in these organisms. In our efforts to understand the role of γ‐tubulin in cell cycle regulation, we have created functional fluorescent protein fusions of four SAC proteins in A spergillus nidulans , the homologs of M ad2, M ps1, B ub1/ B ub R 1 and B ub3. Time‐lapse imaging reveals that SAC proteins are in distinct compartments of the cell until early mitosis when they co‐localize at the spindle pole body. SAC activity is, thus, spatially regulated in A . nidulans . Likewise, C dc20, an activator of the anaphase‐promoting complex/cyclosome, is excluded from interphase nuclei, but enters nuclei at mitotic onset and accumulates to a higher level in mitotic nuclei than in the surrounding nucleoplasm before leaving in anaphase/telophase. The activity of this critical cell cycle regulatory complex is likely regulated by the location of C dc20. Finally, the γ‐tubulin mutation mip A D 159 causes a nuclear‐specific failure of nuclear localization of M ps1 and B ub1/ R 1 but not of C dc20, B ub3 or M ad2.