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The role of protein-tyrosine phosphatase 1B in integrin signaling

Fubo Liang1, Seung-Yub Lee, Jiao Liang

  • 1Departments of Molecular Pharmacology and Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461.

The Journal of Biological Chemistry
|May 4, 2005
PubMed

Insights

Protein-tyrosine phosphatase 1B (PTP1B) inhibitors block cell migration by preventing Src kinase activation. PTP1B promotes integrin signaling by dephosphorylating Src, a key step in cell movement.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Molecular Biology

Background:

  • Protein-tyrosine phosphatase 1B (PTP1B) is a crucial regulator of insulin and leptin signaling pathways.
  • PTP1B is a therapeutic target for metabolic disorders like type 2 diabetes and obesity.
  • Understanding PTP1B's role in diverse signaling pathways, including integrin signaling, is vital.

Purpose of the Study:

  • To investigate the physiological role of PTP1B in integrin signaling using selective inhibitors.
  • To elucidate the molecular mechanisms by which PTP1B influences cell migration and adhesion.

Main Methods:

  • Utilized potent and selective PTP1B small molecule inhibitors.
  • Employed PTP1B "substrate-trapping" mutants.
  • Analyzed protein phosphorylation states (Src, FAK, p130(Cas), ERK1/2) via Western blotting.
  • Investigated protein-protein interactions using co-immunoprecipitation.

Main Results:

  • PTP1B inhibition suppressed fibroblast cell spreading and migration on fibronectin.
  • Inhibition led to increased Tyr(527) phosphorylation of Src and decreased phosphorylation of FAK, p130(Cas), and ERK1/2.
  • PTP1B directly dephosphorylates inhibitory pTyr(527) on Src, activating the kinase.
  • PTP1B forms a complex with Src and p130(Cas), with a specific proline-rich motif in PTP1B essential for binding.

Conclusions:

  • PTP1B promotes integrin-mediated cell responses by activating Src kinase through dephosphorylation of Tyr(527).
  • The interaction between PTP1B, Src, and p130(Cas) is critical for PTP1B's substrate specificity.
  • PTP1B plays a significant role in regulating cell migration and adhesion processes.

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