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Tumor suppressor Fbxw7 regulates TGFβ signaling by targeting TGIF1 for degradation

M T Bengoechea-Alonso1, J Ericsson

  • 1School of Medicine and Medical Science, UCD Conway Institute, University College Dublin, Dublin, Ireland.

Oncogene
|July 13, 2010
PubMed

Insights

Fbxw7 ubiquitin ligase targets TGIF1 for degradation, regulating transforming growth factor-β (TGFβ) signaling. Fbxw7 inactivation stabilizes TGIF1, impairing TGFβ-dependent transcription, cell growth, and migration, suggesting Fbxw7 as a novel TGFβ pathway regulator.

Area of Science:

  • Molecular Biology
  • Cellular Signaling
  • Cancer Biology

Background:

  • Transforming growth factor-β (TGFβ) signaling controls vital cellular functions and is implicated in diseases like cancer.
  • TGIF1 is a transcriptional repressor that negatively regulates TGFβ signaling.
  • Fbxw7 is a tumor suppressor and substrate-recognition factor for a ubiquitin ligase complex.

Purpose of the Study:

  • To investigate the role of Fbxw7 in regulating TGIF1 and TGFβ signaling.
  • To determine if Fbxw7 targets TGIF1 for degradation.
  • To elucidate the impact of Fbxw7 inactivation on TGFβ-dependent cellular processes.

Main Methods:

  • Investigated TGIF1 degradation by Fbxw7 using biochemical assays.
  • Analyzed the effect of Fbxw7 inactivation on TGIF1 levels and TGFβ transcriptional activity.
  • Examined TGFβ-dependent cell growth and migration in cancer cell lines with Fbxw7 mutations.

Main Results:

  • TGIF1 is degraded by Fbxw7 in a phosphorylation-dependent manner.
  • Fbxw7 inactivation leads to accumulation of phosphorylated TGIF1 and repression of TGFβ signaling.
  • Cancer cells with inactivating Fbxw7 mutations exhibit elevated TGIF1 and reduced TGFβ signaling, impacting cell growth and migration.

Conclusions:

  • Fbxw7 targets TGIF1 for degradation, acting as a novel regulator of TGFβ signaling.
  • Fbxw7-mediated regulation of TGIF1 is crucial for controlling TGFβ-dependent cellular processes.
  • Dysregulation of the Fbxw7-TGIF1 axis contributes to aberrant TGFβ signaling in cancer.

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