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Identification of Tek/Tie2 binding partners. Binding to a multifunctional docking site mediates cell survival and

N Jones1, Z Master, J Jones

  • 1Division of Cancer Biology Research, Sunnybrook and Women's College Health Sciences Centre, University of Toronto, Toronto, Ontario M4N 3M5.

The Journal of Biological Chemistry
|October 16, 1999
PubMed

Insights

The Tek/Tie2 receptor tyrosine kinase is crucial for blood vessel and blood cell development. Angiopoietin-1 activates Tek, initiating cell migration and survival pathways via a key docking site.

Area of Science:

  • Molecular Biology
  • Cell Biology
  • Biochemistry

Background:

  • The Tek/Tie2 receptor tyrosine kinase is essential for vascular and hematopoietic development.
  • Understanding Tek-mediated signal transduction is critical for elucidating these developmental processes.

Purpose of the Study:

  • To identify signaling molecules that associate with the phosphorylated Tek receptor.
  • To investigate the functional significance of the Tek receptor's multisubstrate docking site.

Main Methods:

  • Yeast two-hybrid system to identify interacting proteins.
  • Site-directed mutagenesis to map binding sites on the Tek receptor.
  • Stimulation of Tek-expressing cells with Angiopoietin-1.

Main Results:

  • Five signaling molecules (Grb2, Grb7, Grb14, Shp2, p85 subunit of PI3K) bind to Tek via their SH2 domains.
  • A multisubstrate docking site (Tyr(1100)) in Tek's carboxyl tail mediates these interactions.
  • Mutation of Tyr(1100) impairs Grb2/Grb7 binding and subsequent phosphorylation events.
  • Angiopoietin-1 stimulation activates Tek, leading to p85 phosphorylation and downstream cell migration/survival signaling.

Conclusions:

  • Tek receptor signaling is mediated by a multifunctional docking site.
  • This docking site is crucial for activating both endothelial cell migration and survival pathways.
  • Phosphatidylinositol 3-kinase (PI3K) plays a partial role in Angiopoietin-1-induced signaling.

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