Mechanism of Aurora-B degradation and its dependency on intact KEN and A-boxes: identification of an aneuploidy-promoting property.
The kinase Aurora-B, a regulator of chromosome segregation and cytokinesis, is highly expressed in a variety of tumors. During the cell cycle, the level of this protein is tightly controlled, and its deregulated abundance is suspected to contribute to aneuploidy. Here, we provide evidence that Aurora-B is a short-lived protein degraded by the proteasome via the anaphase-promoting cyclosome complex (APC/c) pathway. Aurora-B interacts with the APC/c through the Cdc27 subunit, Aurora-B is ubiquitinated, and its level is increased upon treatment with inhibitors of the proteasome. Aurora-B binds in vivo to the degradation-targeting proteins Cdh1 and Cdc20, the overexpression of which accelerates Aurora-B degradation. Using deletions or point mutations of the five putative degradation signals in Aurora-B, we show that degradation of this protein does not depend on its D-boxes (RXXL), but it does require intact KEN boxes and A-boxes (QRVL) located within the first 65 amino acids. Cells transfected with wild-type or A-box-mutated or KEN box-mutated Aurora-B fused to green fluorescent protein display the protein localized to the chromosomes and then to the midzone during mitosis, but the mutated forms are detected at greater intensities. Hence, we identified the degradation pathway for Aurora-B as well as critical regions for its clearance. Intriguingly, overexpression of a stable form of Aurora-B alone induces aneuploidy and anchorage-independent growth.
Nguyen
Hao G
HG
Department of Biochemistry, Whitaker Cardiovascular Institute, Boston University School of Medicine, 715 Albany Street, K225, Boston, MA 02118, USA.
Chinnappan
Dharmaraj
D
Urano
Takeshi
T
Ravid
Katya
K
D020816:Amino Acid Motifs; D064173:Anaphase-Promoting Complex-Cyclosome; D000782:Aneuploidy; D000818:Animals; D000970:Antineoplastic Agents / Q000378:metabolism; D064191:Apc3 Subunit, Anaphase-Promoting Complex-Cyclosome; D064107:Aurora Kinase B; D064127:Aurora Kinases; D064199:Cdc20 Proteins; D002453:Cell Cycle / Q000502:physiology; D018797:Cell Cycle Proteins / Q000378:metabolism; D002875:Chromosomes / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D007976:Leupeptins / Q000378:metabolism; D008969:Molecular Sequence Data; D015739:Nocodazole / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D061988:Proteasome Inhibitors; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism; D043743:Ubiquitin-Protein Ligase Complexes / Q000378:metabolism*
D000970:Antineoplastic Agents; D064191:Apc3 Subunit, Anaphase-Promoting Complex-Cyclosome; C577366:CDC27 protein, human; D064199:Cdc20 Proteins; D018797:Cell Cycle Proteins; D015853:Cysteine Proteinase Inhibitors; D007976:Leupeptins; D061988:Proteasome Inhibitors; D011993:Recombinant Fusion Proteins; D025801:Ubiquitin; C577488:CDC20 protein, human; D043743:Ubiquitin-Protein Ligase Complexes; D064173:Anaphase-Promoting Complex-Cyclosome; C576921:AURKB protein, human; D064107:Aurora Kinase B; D064127:Aurora Kinases; D017346:Protein Serine-Threonine Kinases; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde; D015739:Nocodazole