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Signal transduction through the IL-4 and insulin receptor families

L M Wang1, A Keegan, M Frankel

  • 1Laboratory of Cellular and Molecular Biology, National Cancer Institute, Bethesda, MD 20892, USA.

Stem Cells (Dayton, Ohio)
|July 1, 1995
PubMed

Insights

Ligand stimulation activates tyrosine kinases, crucial for cell growth signaling. Insulin/IGF-1 receptors and hematopoietin receptors trigger intracellular kinases, leading to substrate tyrosine phosphorylation.

Area of Science:

  • Cellular signaling pathways
  • Molecular biology
  • Signal transduction

Background:

  • Receptor and intracellular tyrosine kinases are vital for mitogenic signal transduction.
  • Insulin and IGF-1 receptors possess intrinsic tyrosine kinase domains, autophosphorylating upon ligand binding.
  • IRS-1 and 4PS are key substrates phosphorylated by insulin and IGF-1, acting as docking sites for SH2-containing signaling molecules.

Purpose of the Study:

  • To explore the role of tyrosine kinases in signal transduction pathways.
  • To elucidate the mechanisms of substrate phosphorylation in response to various receptor activations.
  • To investigate the involvement of intracellular kinases in hematopoietin receptor signaling.

Main Methods:

  • Analysis of receptor tyrosine kinase activation and autophosphorylation.
  • Investigation of insulin receptor substrate 1 (IRS-1) and 4PS phosphorylation.
  • Examination of SH2-containing molecule binding to phosphorylated substrates.
  • Study of intracellular kinase activation downstream of hematopoietin receptors.

Main Results:

  • Insulin and IGF-1 receptors activate cytoplasmic tyrosine kinases, leading to IRS-1 and 4PS phosphorylation.
  • IRS-1 and 4PS contain SH2-binding motifs, facilitating interactions with signaling molecules like PI-3 kinase, SHPTP-2, and Grb-2.
  • Hematopoietin receptors, lacking intrinsic kinase activity, activate intracellular tyrosine kinases.
  • Cytokine receptor stimulation leads to tyrosine phosphorylation of multiple substrates, involving Janus kinases (JAKs) and potentially Fes.

Conclusions:

  • Tyrosine phosphorylation is a central mechanism in both receptor tyrosine kinase and hematopoietin receptor signaling.
  • IRS-1 and 4PS serve as critical adaptors, integrating signals from various pathways.
  • Intracellular tyrosine kinases, particularly JAKs, play a significant role in mediating cytokine-induced signaling through hematopoietin receptors.

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