Activating and silencing the mitotic checkpoint through CENP-E-dependent activation/inactivation of BubR1.
The mitotic checkpoint prevents advance to anaphase prior to successful attachment of every centromere/kinetochore to mitotic spindle microtubules. Using purified components and Xenopus egg extracts, the kinetochore-associated microtubule motor CENP-E is now shown to be the activator of the essential checkpoint kinase BubR1. Since kinase activity and the checkpoint are silenced following CENP-E-dependent microtubule attachment in extracts or binding of CENP-E antibodies that do not disrupt CENP-E association with BubR1, CENP-E mediates silencing of BubR1 signaling. Checkpoint signaling requires the normal level of BubR1 containing a functional Mad3 domain implicated in Cdc20 binding, but only a small fraction need be kinase competent. This supports bifunctional roles for BubR1 in the checkpoint: an enzymatic one requiring CENP-E-dependent activation of its kinase activity at kinetochores and a stoichiometric one as a direct inhibitor of Cdc20.
Mao
Yinghui
Y
Ludwig Institute for Cancer Research, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA.
Abrieu
Ariane
A
Cleveland
Don W
DW
D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D002457:Cell Extracts; D002478:Cells, Cultured; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism*; D005057:Eukaryotic Cells / Q000166:cytology / Q000378:metabolism*; D005260:Female; D020868:Gene Silencing / Q000502:physiology; D018816:Genes, cdc / Q000502:physiology*; D018386:Kinetochores / Q000378:metabolism; D008870:Microtubules / Q000235:genetics / Q000378:metabolism; D008938:Mitosis / Q000235:genetics*; D009865:Oocytes; D011485:Protein Binding / Q000235:genetics; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases; D017434:Protein Structure, Tertiary / Q000235:genetics; D008941:Spindle Apparatus / Q000235:genetics / Q000378:metabolism; D014982:Xenopus laevis
D018797:Cell Cycle Proteins; D002457:Cell Extracts; D002868:Chromosomal Proteins, Non-Histone; C068688:centromere protein E; D011494:Protein Kinases; C090464:Bub1 spindle checkpoint protein; D017346:Protein Serine-Threonine Kinases