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Functional redundancy between Cdc20 ubiquitination and p31 comet
Author(s) -
Jia Luying,
Li Bing,
Warrington Ross,
Hao Xing,
Wang Shixuan,
Yu Hongtao
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.934.6
Subject(s) - microbiology and biotechnology , spindle checkpoint , cdc20 , mad2 , anaphase promoting complex , biology , cell cycle checkpoint , kinetochore , chemistry , comet , spindle apparatus , cell cycle , anaphase , genetics , cell division , cell , chromosome , gene , astrobiology
The spindle checkpoint senses unattached kinetochores in a mitotic cell, and inhibits the function of Cdc20, the mitotic activator of the anaphase‐promoting complex or cyclosome (APC/C), thus delaying anaphase onset. Upon checkpoint activation, unattached kinetochores recruit checkpoint proteins and produce diffusible APC/C‐inhibitory signals. The mitotic checkpoint complex (MCC) consisting of BubR1 (Mad3 in yeast), Bub3, Mad2, and Cdc20 is a critical checkpoint inhibitor of APC/C. When all kinetochores achieve proper microtubule attachment and are under tension, the spindle checkpoint turns off and MCC disassembles to allow APC/C activation. Several mechanisms have been implicated in MCC disassembly, including p31 comet ‐and UbcH10‐dependent Cdc20 autoubiquitination and proteasomal degradation. However, the role of Cdc20 autoubiquitination in checkpoint inactivation has remained controversial, because preventing Cdc20 ubiquitination by mutating all lysines in Cdc20 to arginines does not prevent MCC disassembly. In this study, we have further investigated the roles and coordination of p31 comet , proteasomal degradation, and Cdc20 ubiquitination in MCC disassembly. We show that both the proteasome and p31 comet are required for timely MCC disassembly in HeLa cells by treatment of proteasome inhibitor MG132 or RNA interference (RNAi). Depletion of p31 comet further delays MCC disassembly in cells treated with MG132, suggesting that p31 comet has a proteasome‐independent role. Consistently, p31 comet depletion delays Mad2–Cdc20 dissociation and mitotic exit in cells expressing Cdc20 mutants deficient for autoubiquitination. Taken together, our results reconcile earlier conflicting data, and suggest p31 comet and Cdc20 ubiquitination act in somewhat redundant pathways to promote MCC disassembly.