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An F-box protein, FBXW5, negatively regulates TAK1 MAP3K in the IL-1beta signaling pathway

Yasumasa Minoda1, Hiroaki Sakurai, Takashi Kobayashi

  • 1Division of Molecular and Cellular Immunology, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan.

Biochemical and Biophysical Research Communications
|February 24, 2009
PubMed

Insights

FBXW5 is a newly discovered protein that regulates TAK1 activity in the IL-1beta signaling pathway. This finding clarifies how TAK1 activation is terminated, offering new insights into inflammatory responses.

Area of Science:

  • Cellular signaling pathways
  • Molecular biology
  • Immunology

Background:

  • Transforming growth factor-beta-activated kinase 1 (TAK1) is crucial for activating JNK/p38 MAPKs and IKK in IL-1beta and TNFalpha signaling.
  • TAK1 activation is rapid and transient, but the mechanisms for its termination remain largely unknown.

Purpose of the Study:

  • To identify molecules involved in the negative regulation of TAK1 activity.
  • To elucidate the role of novel regulatory factors in the IL-1beta signaling pathway.

Main Methods:

  • Tandem affinity purification (TAP) in HeLa cells stably expressing TAP-tagged TAK1.
  • Co-immunoprecipitation assays to assess protein interactions.
  • Western blotting to evaluate protein phosphorylation and signaling pathway activation.

Main Results:

  • FBXW5, an F-box protein, was identified as a novel component of the IL-1beta-induced TAK1 complex.
  • FBXW5 binds to TAK1 in an IL-1beta-dependent manner.
  • Overexpression of FBXW5 inhibited IL-1beta-induced JNK/p38 MAPKs and NF-kappaB activation, and TAK1 phosphorylation.
  • FBXW5 knockdown led to prolonged TAK1 activation following IL-1beta stimulation.

Conclusions:

  • FBXW5 negatively regulates TAK1 activity within the IL-1beta signaling pathway.
  • FBXW5 plays a critical role in terminating TAK1 activation, thereby controlling inflammatory responses.

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