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Jab1/CSN5 induces the cytoplasmic localization and degradation of RUNX3

Jang-Hyun Kim1, Joong-Kook Choi, Senthilkumar Cinghu

  • 1Department of Biochemistry, School of Medicine, Institute for Tumor Research, Chungbuk National University, Cheongju 361-763, South Korea.

Journal of Cellular Biochemistry
|April 8, 2009
PubMed

Insights

Jun-activation domain-binding protein 1 (Jab1/CSN5) targets the tumor suppressor RUNX3 for degradation. This involves Jab1 facilitating RUNX3 nuclear export, leading to its proteasomal breakdown and impacting cancer development.

Area of Science:

  • Molecular Biology
  • Cancer Research
  • Cell Biology

Background:

  • Runt-related transcription factors (RUNX) are crucial in development and cancer.
  • RUNX3 acts as a tumor suppressor, often inactivated in gastric and breast cancers.
  • Jun-activation domain-binding protein 1 (Jab1/CSN5), a COP9 signalosome component, degrades tumor suppressors.

Purpose of the Study:

  • To investigate the mechanism regulating RUNX3 stability.
  • To determine the role of Jab1/CSN5 in RUNX3 regulation.

Main Methods:

  • Studied the interaction between Jab1/CSN5 and RUNX3.
  • Investigated the role of the COP9 signalosome (CSN) complex in RUNX3 nuclear export and degradation.
  • Utilized proteasome inhibition assays.

Main Results:

  • Jab1 facilitates the nuclear export of RUNX3, a process influenced by CSN-associated kinases.
  • Cytoplasmic RUNX3 is rapidly degraded via a proteasome-dependent pathway.
  • Identified a novel regulatory mechanism for RUNX3 stability and localization.

Conclusions:

  • The CSN complex, via Jab1, controls RUNX3 nuclear export and protein stability.
  • This mechanism offers new insights into RUNX3 regulation in cancer.
  • Targeting this pathway could be relevant for cancer therapy.

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