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Method for Measuring the Activity of Deubiquitinating Enzymes in Cell Lines and Tissue Samples
09:45

Method for Measuring the Activity of Deubiquitinating Enzymes in Cell Lines and Tissue Samples

Published on: May 10, 2015

USP1 deubiquitinates ID proteins to preserve a mesenchymal stem cell program in osteosarcoma

Samuel A Williams1, Heather L Maecker, Dorothy M French

  • 1Department of Physiological Chemistry, Genentech, Inc., 1 DNA Way, South San Francisco, CA 94080, USA.

Cell
|September 20, 2011
PubMed

Insights

The deubiquitinating enzyme USP1 stabilizes Inhibitors of DNA binding (ID) proteins, maintaining stem cell characteristics in osteosarcoma. Targeting USP1 could offer a new therapeutic strategy for osteosarcoma differentiation therapy.

Area of Science:

  • Molecular Biology
  • Cancer Biology
  • Stem Cell Biology

Background:

  • Inhibitors of DNA binding (ID) proteins are crucial for maintaining stem cell fate by inhibiting differentiation.
  • While ID proteins are typically degraded in differentiated tissues, they often persist in neoplasms.
  • The mechanisms regulating ID protein stability in cancer remain incompletely understood.

Purpose of the Study:

  • To investigate the role of the deubiquitinating enzyme USP1 in regulating ID protein stability.
  • To determine USP1's contribution to stem cell-like characteristics in osteosarcoma.
  • To explore USP1 as a potential therapeutic target for osteosarcoma.

Main Methods:

  • Immunoprecipitation and Western blotting to assess USP1-ID protein interactions and ubiquitination status.
  • USP1 knockdown and overexpression experiments in osteosarcoma and mesenchymal stem cells.
  • Assessment of cell proliferation, cell-cycle arrest, and osteogenic differentiation markers.
  • Analysis of USP1 and ID protein expression in primary human osteosarcoma samples.
  • Phenotypic analysis of USP1-deficient mice.

Main Results:

  • USP1 directly binds to and deubiquitinates ID1, ID2, and ID3, thereby stabilizing these proteins.
  • Co-overexpression of USP1 and ID proteins was observed in a subset of human osteosarcomas.
  • USP1 knockdown in osteosarcoma cells led to ID protein destabilization, cell-cycle arrest, and induced osteogenic differentiation.
  • Ectopic USP1 expression in mesenchymal stem cells promoted proliferation and inhibited osteoblastic differentiation.
  • USP1 deficiency in mice resulted in osteopenia, indicating its role in bone homeostasis.

Conclusions:

  • USP1 plays a critical role in stabilizing ID proteins, promoting stem cell-like properties in osteosarcoma.
  • USP1 is implicated in preserving the stem cell state characteristic of osteosarcoma.
  • USP1 represents a promising therapeutic target for inducing differentiation in osteosarcoma.

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