Ligand oligomerization state controls Tie2 receptor trafficking and angiopoietin-2-specific responses

J Cell Sci. 2012 May 1;125(Pt 9):2212-23. doi: 10.1242/jcs.098020. Epub 2012 Feb 22.

Abstract

Angiopoietin 1 (Ang1) is an activating ligand for the endothelial receptor tyrosine kinase Tie2, whereas Ang2 acts as a context-dependent agonist or antagonist that has a destabilizing effect on the vasculature. The molecular mechanisms responsible for the versatile functions of Ang2 are poorly understood. We show here that Ang2, but not Ang1, induces Tie2 translocation to the specific cell-matrix contact sites located at the distal end of focal adhesions. The Ang2-specific Tie2 translocation was associated with distinct Tie2 activation and downstream signals which differed from those of Ang1, and led to impaired cell motility and weak cell-matrix adhesion. We demonstrate that the different oligomeric or multimeric forms of the angiopoietins induce distinct patterns of Tie2 trafficking; the lower oligomerization state of native Ang2 was crucial for the Ang2-specific Tie2 redistribution, whereas multimeric structures of Ang1 and Ang2 induced similar responses. The Ang2-specific Tie2 trafficking to cell-matrix contacts was also dependent on the cell substratum, α2β1-integrin-containing cell-matrix adhesion sites and intact microtubules. Our data indicate that the different subcellular trafficking of Tie2-Ang2 and Tie2-Ang1 complexes generates ligand-specific responses in the angiopoietin-Tie signaling pathway, including modulation of cell-matrix interactions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Angiopoietin-1 / chemistry*
  • Angiopoietin-1 / genetics
  • Angiopoietin-1 / pharmacology
  • Angiopoietin-2 / chemistry*
  • Angiopoietin-2 / genetics
  • Angiopoietin-2 / pharmacology
  • Animals
  • Cell Adhesion / drug effects
  • Cell Adhesion / genetics
  • Cell Movement / drug effects
  • Cell Movement / genetics
  • Cell-Matrix Junctions / drug effects
  • Cell-Matrix Junctions / metabolism
  • Endothelium, Vascular / cytology
  • Endothelium, Vascular / drug effects
  • Endothelium, Vascular / metabolism*
  • Gene Expression / drug effects
  • Human Umbilical Vein Endothelial Cells
  • Humans
  • Integrin alpha2beta1 / genetics
  • Integrin alpha2beta1 / metabolism
  • Intravitreal Injections
  • Mice
  • Microtubules / drug effects
  • Microtubules / metabolism
  • NIH 3T3 Cells
  • Neovascularization, Physiologic
  • Protein Multimerization
  • Receptor Protein-Tyrosine Kinases / genetics
  • Receptor Protein-Tyrosine Kinases / metabolism*
  • Receptor, TIE-2
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / pharmacology
  • Signal Transduction / drug effects
  • Vitreous Body / blood supply*

Substances

  • Angiopoietin-1
  • Angiopoietin-2
  • Integrin alpha2beta1
  • Recombinant Fusion Proteins
  • Receptor Protein-Tyrosine Kinases
  • Receptor, TIE-2
  • Tek protein, mouse