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Light-mediated Reversible Modulation of the Mitogen-activated Protein Kinase Pathway during Cell Differentiation and Xenopus Embryonic Development
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Anaphase-Promoting Complex Adaptor FZR1/CDH1 Blocks BRAF Signaling Both by Targeting BRAF for Proteolytic Degradation

Chao Zhang1, Gideon Bollag2

  • 1Plexxikon Inc., Berkeley, California.

Cancer Discovery
|April 5, 2017
PubMed

Insights

Researchers found that FZR1 targets BRAF for degradation, a novel mechanism that also disrupts BRAF dimerization. This discovery has significant implications for understanding cell fate and FZR1's tumor suppressor functions.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Oncology

Background:

  • BRAF kinase activity is regulated by protein dimerization and degradation.
  • The anaphase-promoting complex/cyclosome (APC/C) is a key regulator of cell cycle progression.
  • FZR1 (also known as CDH1) is a cofactor for the APC/C.

Purpose of the Study:

  • To investigate the role of the APC/CFZR1 system in regulating BRAF activity.
  • To identify novel mechanisms controlling BRAF protein levels and function.

Main Methods:

  • Ubiquitination assays
  • Co-immunoprecipitation
  • Western blotting
  • Cell-based assays to assess BRAF activity and dimerization

Main Results:

  • BRAF is identified as a substrate of the APC/CFZR1-ubiquitin-proteasome system.
  • FZR1 binds to BRAF, inducing a conformational change that inhibits BRAF dimerization.
  • APC/CFZR1-mediated BRAF degradation is demonstrated.

Conclusions:

  • The APC/CFZR1 complex directly regulates BRAF activity through protein degradation and disruption of dimerization.
  • This interaction highlights a novel regulatory pathway for BRAF with implications for cancer development.
  • FZR1's role as a tumor suppressor is further elucidated through its control of BRAF signaling.

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