Reduction of Protein-Tyrosine phosphatase-1B Increases Insulin Signaling in FAO Hepatoma Cells

Biochem Biophys Res Commun. 2003 Jan 10;300(2):261-7. doi: 10.1016/s0006-291x(02)02839-5.

Abstract

Protein-tyrosine phosphatase-1B (PTP1B) has been implicated as a negative regulator of insulin signaling. PTP1B dephosphorylates the insulin receptor and insulin receptor substrates (IRS-1/2), inhibiting the insulin-signaling pathway. PTP1B has been reported to be elevated in diabetes and insulin-resistant states. Conversely, PTP1B null mice have increased insulin sensitivity. To further investigate the effect of PTP1B reduction on insulin signaling, FAO rat hepatoma cells were transfected, by electroporation, with a specific PTP1B antisense oligonucleotide (ASO), or a control oligonucleotide. The PTP1B ASO caused a 50-70% reduction in PTP1B protein expression as measured by Western blot analysis. Upon insulin stimulation, an increase in the phosphorylation of the insulin receptor and insulin receptor substrates was observed, without any change in protein expression levels. Reduction of PTP1B expression in FAO cells also caused an increase in insulin-stimulated phosphorylation of PKB and GSK3, without any change in protein expression. These results demonstrate that reduction of PTP1B can modulate key insulin signaling events downstream of the insulin receptor.

MeSH terms

  • Animals
  • Carcinoma, Hepatocellular
  • Dose-Response Relationship, Drug
  • Glycogen Synthase Kinase 3 / metabolism
  • Insulin / pharmacology*
  • Insulin Receptor Substrate Proteins
  • Intracellular Signaling Peptides and Proteins
  • Mitogen-Activated Protein Kinases / metabolism
  • Oligonucleotides, Antisense / genetics
  • Phosphoproteins / metabolism
  • Phosphorylation
  • Protein Tyrosine Phosphatase, Non-Receptor Type 1
  • Protein Tyrosine Phosphatases / genetics
  • Protein Tyrosine Phosphatases / physiology*
  • Protein-Serine-Threonine Kinases*
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-akt
  • Rats
  • Receptor, Insulin / metabolism
  • Signal Transduction*
  • Tumor Cells, Cultured

Substances

  • Insulin
  • Insulin Receptor Substrate Proteins
  • Intracellular Signaling Peptides and Proteins
  • Irs1 protein, mouse
  • Irs1 protein, rat
  • Irs2 protein, mouse
  • Irs2 protein, rat
  • Oligonucleotides, Antisense
  • Phosphoproteins
  • Proto-Oncogene Proteins
  • Receptor, Insulin
  • Protein-Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Mitogen-Activated Protein Kinases
  • Glycogen Synthase Kinase 3
  • Protein Tyrosine Phosphatase, Non-Receptor Type 1
  • Protein Tyrosine Phosphatases
  • Ptpn1 protein, rat