Effects of phosphatase and proteasome inhibitors on Borealin phosphorylation and degradation

The chromosomal passenger complex (CPC) senses tension defects at the kinetochore to activate the spindle assembly checkpoint, and helps to position the cleavage furrow. The CPC, consisting of INCENP, Survivin, Borealin and Aurora B localizes to the inner centromere at metaphase and re-localizes to...

Full description

Saved in:
Bibliographic Details
Published in:Journal of biochemistry (Tokyo) 2012-04, Vol.151 (4), p.361-369
Main Authors: Date, Dipali, Dreier, Megan R, Borton, Michael T, Bekier, 2nd, Michael E, Taylor, William R
Format: Article
Language:English
Subjects:
Acetylcysteine - analogs & derivatives
Acetylcysteine - pharmacology
Amino Acid Substitution
CDC2 Protein Kinase - chemistry
CDC2 Protein Kinase - genetics
CDC2 Protein Kinase - metabolism
Cell Cycle Proteins - chemistry
Cell Cycle Proteins - genetics
Cell Cycle Proteins - metabolism
Dual-Specificity Phosphatases - genetics
Dual-Specificity Phosphatases - metabolism
Gene Expression
HeLa Cells
Humans
Leupeptins - pharmacology
Okadaic Acid - pharmacology
Peptide Fragments - metabolism
Phosphoric Monoester Hydrolases - antagonists & inhibitors
Phosphorylation
Proteasome Inhibitors
Protein Processing, Post-Translational
Protein Transport
Proteolysis - drug effects
Regular Papers
Ubiquitin - metabolism
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The chromosomal passenger complex (CPC) senses tension defects at the kinetochore to activate the spindle assembly checkpoint, and helps to position the cleavage furrow. The CPC, consisting of INCENP, Survivin, Borealin and Aurora B localizes to the inner centromere at metaphase and re-localizes to the spindle midzone at anaphase; several CPC functions are regulated by post-translational modification. Borealin is phosphorylated at multiple sites and phosphorylation at S219 causes Borealin to migrate more slowly upon electrophoresis. Here we find that Cdk1 can induce a mobility shift of Borealin, suggesting that S219 phosphorylation is under Cdk1 control. However, Cdk1 is inefficient at phosphorylating purified Borealin in vitro. A yeast orthologue of Borealin, Npl1, is dephosphorylated by the phosphatase Cdc14. We find no difference in the mobility shift of Borealin in human cells lacking either Cdc14A or Cdc14B. In contrast, the phosphatase inhibitor okadaic acid does delay the dephosphorylation of Borealin as cells exit mitosis. The proteasome inhibitor MG132 reduces Borealin phosphorylation in mitosis and increases the steady-state level of Borealin, especially in mutants lacking the C-terminus. However, a second, structurally unrelated proteasome inhibitor, lactacystin did not up-regulate Borealin. These results suggest that the effect of MG132 on Borealin is due to the inhibition of an intracellular protease other than the proteasome.
ISSN:0021-924X
1756-2651
DOI:10.1093/jb/mvs015