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PTEN is a protein tyrosine phosphatase for IRS1

Yuji Shi1, Junru Wang1, Sarat Chandarlapaty2

  • 1Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.

Nature Structural & Molecular Biology
|May 13, 2014
PubMed

Insights

The PTEN tumor suppressor acts as a protein phosphatase for insulin receptor substrate-1 (IRS1), regulating insulin and IGF signaling. Its antagonism by NEDD4 promotes tumor cell proliferation and glucose metabolism.

Area of Science:

  • Molecular Biology
  • Cell Signaling
  • Cancer Research

Background:

  • PTEN (Phosphatase and tensin homolog) is primarily known for its lipid phosphatase activity, crucial in tumor suppression.
  • Insulin receptor substrate-1 (IRS1) is a key mediator in insulin and insulin-like growth factor (IGF) signaling pathways.

Purpose of the Study:

  • To investigate the protein phosphatase activity of PTEN.
  • To elucidate the role of PTEN in IRS1 dephosphorylation and its impact on insulin and IGF signaling.
  • To determine the interplay between PTEN, NEDD4, and IGF signaling in cellular processes.

Main Methods:

  • Biochemical analysis to assess PTEN's phosphatase activity towards IRS1.
  • Cellular reconstitution experiments to validate PTEN's function.
  • Investigation of signaling pathways (IGF, insulin, EGF) in cells with varying PTEN and NEDD4 levels.

Main Results:

  • Mammalian PTEN functions as a protein tyrosine phosphatase, specifically dephosphorylating IRS1.
  • NEDD4, a PTEN ubiquitin ligase, is essential for proper IGF signaling; its absence leads to defective IRS1 and AKT phosphorylation.
  • PTEN ablation rescues the defective IGF signaling caused by NEDD4 deletion.
  • NEDD4 promotes insulin-mediated glucose metabolism and proliferation of IGF1 receptor-dependent tumor cells.

Conclusions:

  • PTEN acts as a critical protein phosphatase for IRS1, antagonizing IGF and insulin signaling.
  • The PTEN-NEDD4 interaction regulates key cellular processes, including glucose metabolism and tumor cell proliferation.
  • Understanding this PTEN function offers insights into cancer development and metabolic regulation.

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