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Comparative Strategies for Ubiquitination Detection in Mammalian Cell Lysates Using SMAD2/SMURF2 as a Model
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Comparative Strategies for Ubiquitination Detection in Mammalian Cell Lysates Using SMAD2/SMURF2 as a Model

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ErbB2 trafficking and degradation associated with K48 and K63 polyubiquitination

Corina Marx1, Jason M Held, Bradford W Gibson

  • 1Buck Institute for Age Research, Novato, California 94945, USA.

Cancer Research
|April 22, 2010
PubMed

Insights

The HSP90 inhibitor geldanamycin (GA) and proteasome inhibitor bortezomib (PS341) differentially regulate ErbB2/HER2 ubiquitination and degradation. PS341 treatment leads to sequential K48 and K63 polyubiquitination and lysosomal degradation of ErbB2.

Area of Science:

  • Oncology
  • Molecular Biology
  • Cell Biology

Background:

  • ErbB2/HER2 is a key cancer target with poorly understood surface localization and internalization.
  • HSP90 and proteasome inhibitors like GA and PS341 affect ErbB2 levels through distinct mechanisms.

Purpose of the Study:

  • To investigate the differential effects of geldanamycin (GA) and bortezomib (PS341) on ErbB2/HER2 polyubiquitination and degradation pathways.
  • To elucidate the roles of K48-linked and K63-linked polyubiquitin chains in regulating ErbB2 trafficking and lysosomal degradation.

Main Methods:

  • Utilized multiple reaction monitoring (MRM)/mass spectrometry (MS) to quantify ErbB2 polyubiquitination.
  • Employed polyubiquitin linkage-specific antibodies to track K48 and K63 linkages.
  • Performed fluorescence microscopic imaging to assess protein colocalization.

Main Results:

  • GA induced rapid, modest, and synchronous K48/K63 polyubiquitination of ErbB2.
  • PS341 induced a dramatic, sequential increase in K48-linked followed by K63-linked polyubiquitination.
  • PS341, but not GA, promoted colocalization of polyubiquitinated ErbB2 with lysosomes.

Conclusions:

  • ErbB2 surface expression and recycling are dependent on its polyubiquitination and deubiquitination status.
  • Distinct polyubiquitin editing mechanisms regulate ErbB2 cytoplasmic trafficking and degradation pathways.
  • Targeting these ubiquitination pathways offers potential therapeutic strategies for ErbB2-overexpressing cancers.

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