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The GADD45 inhibition of Cdc2 kinase correlates with GADD45-mediated growth suppression

S Jin1, M J Antinore, F D Lung

  • 1Department of Radiation Oncology, Pittsburgh Cancer Institute, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.

The Journal of Biological Chemistry
|April 5, 2000
PubMed

Insights

Growth arrest protein Gadd45 (GADD45) interacts with Cdc2 via a novel central domain, inhibiting its activity and suppressing cell growth. This interaction is crucial for GADD45-mediated cell cycle G(2)-M arrest.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Genetics

Background:

  • Cell cycle progression is tightly regulated, with checkpoints like the G(2)-M phase crucial for preventing genomic instability.
  • Genotoxic stress triggers cellular responses, including growth arrest, mediated by proteins like Gadd45 (Growth Arrest and DNA Damage-inducible protein 45).
  • Gadd45 is known to interact with Cdc2 (also known as CDK1), a key regulator of the G(2)-M transition, and inhibit its kinase activity.

Purpose of the Study:

  • To identify the specific domains of Gadd45 responsible for its interaction with Cdc2.
  • To elucidate the mechanism by which Gadd45 inhibits Cdc2 kinase activity.
  • To determine the role of the Gadd45-Cdc2 interaction in Gadd45-mediated cell cycle arrest and growth suppression.

Main Methods:

  • Utilized Myc-tagged Gadd45 deletion mutants and an overlapping peptide library for in vitro and in vivo interaction studies.
  • Performed sequence analysis to identify conserved motifs within the Gadd45-Cdc2 binding region.
  • Investigated the effect of disrupting the Gadd45-Cdc2 interaction on Cdc2-cyclin B1 complex formation and cell cycle progression using peptide interference and survival assays.

Main Results:

  • A central region of Gadd45 (amino acids 65-84) was identified as the critical domain for Cdc2 binding.
  • This Gadd45 domain is essential for inhibiting Cdc2 kinase activity and does not share homology with known cyclin-dependent kinase inhibitor motifs.
  • Disruption of this Cdc2-binding motif abolished Gadd45-induced G(2)-M arrest and correlated with reduced Gadd45-mediated growth suppression.

Conclusions:

  • The central region of Gadd45 represents a novel motif mediating direct interaction with and inhibition of Cdc2.
  • Gadd45-induced cell cycle G(2)-M arrest is a primary mechanism underlying its growth-suppressive function.
  • Understanding this novel interaction provides insight into cellular responses to DNA damage and potential therapeutic targets.

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