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Regulation of homeodomain-interacting protein kinase 2 (HIPK2) effector function through dynamic small

Thomas G Hofmann1, Ellis Jaffray, Nicole Stollberg

  • 1Heinrich-Pette-Institut für Experimentelle Virologie und Immunologie an der Universität Hamburg, Martinistrasse 52, 20251 Hamburg, Germany. t.hofmann@dkfz.de

The Journal of Biological Chemistry
|June 17, 2005
PubMed

Insights

Homeodomain-interacting protein kinase 2 (HIPK2) is modified by SUMO-1, impacting its function. This SUMOylation regulates HIPK2

Area of Science:

  • Molecular Biology
  • Cell Signaling
  • Post-translational Modifications

Background:

  • Homeodomain-interacting protein kinase 2 (HIPK2) regulates crucial cellular processes including apoptosis and growth suppression.
  • HIPK2 mediates cell death through p53-dependent and p53-independent pathways, including JNK activation and CtBP degradation.

Purpose of the Study:

  • To investigate the role of small ubiquitin-related modifier-1 (SUMO-1) modification in regulating HIPK2 function.
  • To identify the specific site of SUMOylation on HIPK2 and its functional consequences.

Main Methods:

  • In vitro and in vivo SUMOylation assays using human HIPK2.
  • Site-directed mutagenesis to alter the SUMOylation consensus motif.
  • Co-immunoprecipitation and colocalization studies with SUMO protease SuPr-1.
  • Analysis of JNK activation and antiproliferative effects.

Main Results:

  • Human HIPK2 undergoes SUMO-1 modification at lysine residue 25, a conserved motif.
  • SUMO-1 modification inhibits HIPK2-induced JNK activation and p53-independent antiproliferative activity.
  • SUMO protease SuPr-1 interacts with HIPK2, deconjugates SUMO-1, and modestly enhances JNK activity.

Conclusions:

  • HIPK2 effector function, particularly on JNK signaling, is dynamically regulated by SUMO-1 modification.
  • SUMOylation acts as a key modulator of HIPK2's role in cell signaling and antiproliferative functions.

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