Abstract
Error-free chromosome segregation depends on the precise regulation of phosphorylation to stabilize kinetochore-microtubule attachments (K-fibres) on sister chromatids that have attached to opposite spindle poles (bi-oriented). In many instances, phosphorylation correlates with K-fibre destabilization. Consistent with this, multiple kinases, including Aurora B and Plk1, are enriched at kinetochores of mal-oriented chromosomes when compared with bi-oriented chromosomes, which have stable attachments. Paradoxically, however, these kinases also target to prometaphase chromosomes that have not yet established spindle attachments and it is therefore unclear how kinetochore-microtubule interactions can be stabilized when kinase levels are high. Here we show that the generation of stable K-fibres depends on the B56-PP2A phosphatase, which is enriched at centromeres/kinetochores of unattached chromosomes. When B56-PP2A is depleted, K-fibres are destabilized and chromosomes fail to align at the spindle equator. Strikingly, B56-PP2A depletion increases the level of phosphorylation of Aurora B and Plk1 kinetochore substrates as well as Plk1 recruitment to kinetochores. Consistent with increased substrate phosphorylation, we find that chemical inhibition of Aurora or Plk1 restores K-fibres in B56-PP2A-depleted cells. Our findings reveal that PP2A, an essential tumour suppressor, tunes the balance of phosphorylation to promote chromosome-spindle interactions during cell division.
Publication types
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Research Support, N.I.H., Extramural
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Research Support, Non-U.S. Gov't
MeSH terms
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Aurora Kinase B
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Aurora Kinases
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Benzamides / pharmacology
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Cell Cycle Proteins / antagonists & inhibitors
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Cell Cycle Proteins / metabolism
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Chromosome Segregation* / drug effects
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HeLa Cells
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Humans
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Indoles / pharmacology
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Kinetochores / drug effects
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Kinetochores / enzymology*
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Leupeptins / pharmacology
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Microscopy, Fluorescence
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Microtubules / drug effects
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Microtubules / enzymology*
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Nocodazole / pharmacology
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Phosphorylation
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Polo-Like Kinase 1
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Protein Kinase Inhibitors / pharmacology
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Protein Phosphatase 2 / genetics
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Protein Phosphatase 2 / metabolism*
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Protein Serine-Threonine Kinases / antagonists & inhibitors
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Protein Serine-Threonine Kinases / metabolism
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Proto-Oncogene Proteins / antagonists & inhibitors
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Proto-Oncogene Proteins / metabolism
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Pteridines / pharmacology
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Quinazolines / pharmacology
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RNA Interference
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Recombinant Fusion Proteins / metabolism
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Sulfonamides / pharmacology
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Time Factors
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Transfection
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Tumor Suppressor Proteins / genetics
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Tumor Suppressor Proteins / metabolism*
Substances
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4-(4-(N-benzoylamino)anilino)-6-methoxy-7-(3-(1-morpholino)propoxy)quinazoline
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BI 2536
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Benzamides
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Cell Cycle Proteins
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Indoles
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Leupeptins
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PPP2R5A protein, human
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Protein Kinase Inhibitors
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Proto-Oncogene Proteins
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Pteridines
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Quinazolines
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Recombinant Fusion Proteins
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Sulfonamides
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Tumor Suppressor Proteins
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AURKB protein, human
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Aurora Kinase B
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Aurora Kinases
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Protein Serine-Threonine Kinases
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Protein Phosphatase 2
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hesperadin
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benzyloxycarbonylleucyl-leucyl-leucine aldehyde
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Nocodazole