Activation of Aurora-A kinase by protein phosphatase inhibitor-2, a bifunctional signaling protein

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Updated: Aug 24, 2026

Real-Time Monitoring of Aurora kinase A Activation using Conformational FRET Biosensors in Live Cells
06:29

Real-Time Monitoring of Aurora kinase A Activation using Conformational FRET Biosensors in Live Cells

Published on: July 30, 2020

David L Satinover1, Craig A Leach, P Todd Stukenberg

  • 1Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, VA 22908, USA.

Proceedings of the National Academy of Sciences of the United States of America
|June 3, 2004
PubMed

Insights

Human phosphatase inhibitor-2 (I-2) directly activates Aurora-A kinase, a key player in cell division and cancer. This activation is independent of PP1 inhibition, suggesting I-2 acts as an allosteric activator.

Area of Science:

  • Cell Biology
  • Molecular Oncology
  • Biochemistry

Background:

  • Aurora-A kinase is crucial for cell division, spindle assembly, and chromosome segregation.
  • Overexpression of Aurora-A is linked to multiple human cancers, highlighting its oncogenic potential.
  • Aurora-A activity is regulated by phosphorylation at Thr-288 and allosteric activation by proteins like TPX2.

Purpose of the Study:

  • To investigate the direct interaction and regulatory role of human phosphatase inhibitor-2 (I-2) on Aurora-A kinase activity.
  • To elucidate the mechanism by which I-2 modulates Aurora-A function, particularly in relation to PP1 and TPX2.

Main Methods:

  • In vitro kinase assays using recombinant human Aurora-A and I-2.
  • Site-directed mutagenesis to assess the role of I-2 domains in Aurora-A activation.
  • Co-immunoprecipitation to detect Aurora-A and I-2 complex formation in mitotic cells.

Main Results:

  • Human I-2 directly and specifically stimulated Aurora-A kinase activity in vitro.
  • I-2 activation of Aurora-A was not mediated by PP1 inhibition and was dependent on the C-terminal domain of I-2.
  • Aurora-A and I-2 formed a complex in mitotic HeLa cells, and I-2 activation was not additive with TPX2-mediated activation.

Conclusions:

  • I-2 acts as a direct, allosteric activator of Aurora-A kinase, independent of its PP1 inhibitory function.
  • I-2 is a bifunctional protein, possessing domains for both PP1 inhibition and direct Aurora-A stimulation.
  • These findings reveal a novel regulatory mechanism for Aurora-A, with implications for understanding its role in cancer progression.

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