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E3 ubiquitin ligase Mule targets β-catenin under conditions of hyperactive Wnt signaling

Carmen Dominguez-Brauer1, Rahima Khatun2, Andrew J Elia1

  • 1The Campbell Family Institute for Breast Cancer Research, Ontario Cancer Institute, University Health Network, Toronto, Ontario M5G 2C1, Canada.

Proceedings of the National Academy of Sciences of the United States of America
|February 1, 2017
PubMed

Insights

The protein Mule directly targets beta-catenin for degradation, fine-tuning Wnt signaling. This mechanism acts as a safeguard against tumorigenesis by controlling cell proliferation and stem cell self-renewal.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Oncology

Background:

  • Wnt signaling is crucial for embryonic development and tissue homeostasis, regulating cell proliferation and stem cell self-renewal.
  • Aberrant Wnt pathway activation, often due to mutations like in APC, drives cancer development, particularly in colon cancer.
  • Mule (also known as Huwe1/Arf-BP1) was previously shown to control intestinal stem cell proliferation via c-Myc modulation of the Wnt pathway.

Purpose of the Study:

  • To investigate the role of Mule in oncogenesis by examining its interaction with beta-catenin.
  • To determine if Mule targets beta-catenin for degradation, especially under conditions of hyperactive Wnt signaling.

Main Methods:

  • Investigated the direct interaction between Mule and beta-catenin.
  • Assessed the degradation of beta-catenin mediated by Mule in the context of Wnt pathway activation.

Main Results:

  • Mule directly interacts with beta-catenin.
  • Mule targets beta-catenin for degradation when the Wnt signaling pathway is hyperactive.
  • These findings indicate Mule's role in regulating beta-catenin stability.

Conclusions:

  • Mule plays a significant role in fine-tuning the Wnt pathway through multiple mechanisms.
  • Mule acts as a critical safeguard against tumorigenesis by controlling key Wnt pathway components.
  • Understanding Mule's function provides insights into potential therapeutic strategies for Wnt-driven cancers.
Keywords:
MuleWnt signalingcolorectal cancerstem cellsβ-catenin

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