Angiotensin II subtype 2 receptor activation inhibits insulin-induced phosphoinositide 3-kinase and Akt and induces apoptosis in PC12W cells

Mol Endocrinol. 2002 Sep;16(9):2113-23. doi: 10.1210/me.2001-0284.

Abstract

In the present study, we identified novel negative cross-talk between the angiotensin II subtype 2 (AT2) receptor and insulin receptor signaling in the regulation of phosphoinositide 3-kinase (PI3K), Akt, and apoptosis in rat pheochromocytoma cell line, PC12W cells, which exclusively express AT2 receptor. We demonstrated that insulin-mediated insulin receptor substrate (IRS)-2-associated PI3K activity was inhibited by AT2 receptor stimulation, whereas IRS-1-associated PI3K activity was not significantly influenced. AT2 receptor stimulation did not change insulin-induced tyrosine phosphorylation of IRS-2 or its association with the p85alpha subunit of PI3K, but led to a significant reduction of insulin-induced p85alpha phosphorylation. AT2 receptor stimulation increased the association of a protein tyrosine phosphatase, SHP-1, with IRS-2. Moreover, we demonstrated that AT2 receptor stimulation inhibited insulin-induced Akt phosphorylation and that insulin-mediated antiapoptotic effect was also blocked by AT2 receptor activation. Overexpression of a catalytically inactive dominant negative SHP-1 markedly attenuated the AT2 receptor- mediated inhibition of IRS-2-associated PI3K activity, Akt phosphorylation, and antiapoptotic effect induced by insulin. Taken together, these results indicate that AT2 receptor-mediated activation of SHP-1 and the consequent inhibition IRS-2-associated PI3K activity contributed at least partly to the inhibition of Akt phosphorylation, thereby inducing apoptosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis*
  • Enzyme Activation / drug effects
  • Insulin / pharmacology*
  • Insulin Receptor Substrate Proteins
  • Intracellular Signaling Peptides and Proteins
  • PC12 Cells
  • Phosphatidylinositol 3-Kinases / metabolism*
  • Phosphoinositide-3 Kinase Inhibitors
  • Phosphoproteins / metabolism
  • Phosphorylation
  • Protein Serine-Threonine Kinases*
  • Protein Tyrosine Phosphatase, Non-Receptor Type 6
  • Protein Tyrosine Phosphatases / metabolism
  • Proto-Oncogene Proteins / antagonists & inhibitors
  • Proto-Oncogene Proteins / metabolism*
  • Proto-Oncogene Proteins c-akt
  • Rats
  • Receptor, Angiotensin, Type 2 / metabolism*

Substances

  • Insulin
  • Insulin Receptor Substrate Proteins
  • Intracellular Signaling Peptides and Proteins
  • Irs2 protein, rat
  • Phosphoinositide-3 Kinase Inhibitors
  • Phosphoproteins
  • Proto-Oncogene Proteins
  • Receptor, Angiotensin, Type 2
  • Akt1 protein, rat
  • Protein Serine-Threonine Kinases
  • Proto-Oncogene Proteins c-akt
  • Protein Tyrosine Phosphatase, Non-Receptor Type 6
  • Protein Tyrosine Phosphatases
  • Ptpn6 protein, rat