Role of tyrosine phosphatase SHP-1 in the mechanism of endorepellin angiostatic activity.

Abstract

Endorepellin, the C-terminal domain of perlecan, is a powerful angiogenesis inhibitor. To dissect the mechanism of endorepellin-mediated endothelial silencing, we used an antibody array against multiple tyrosine kinase receptors. Endorepellin caused a widespread reduction in phosphorylation of key receptors involved in angiogenesis and a concurrent increase in phosphatase activity in endothelial cells and tumor xenografts. These effects were efficiently hampered by function-blocking antibodies against integrin alpha2beta1, the functional endorepellin receptor. The Src homology-2 protein phosphatase-1 (SHP-1) coprecipitated with integrin alpha2 and was phosphorylated in a dynamic fashion after endorepellin stimulation. Genetic evidence was provided by lack of an endorepellin-evoked phosphatase response in microvascular endothelial cells derived from integrin alpha2beta1(-/-) mice and by response to endorepellin in cells genetically engineered to express the alpha2beta1 integrin, but not in cells either lacking this receptor or expressing a chimera harboring the integrin alpha2 ectodomain fused to the alpha1 intracellular domain. siRNA-mediated knockdown of integrin alpha2 caused a dose-dependent reduction of SHP-1. Finally, the levels of SHP-1 and its enzymatic activity were substantially reduced in multiple organs from alpha2beta1(-/-) mice. Our results show that SHP-1 is an essential mediator of endorepellin activity and discover a novel functional interaction between the integrin alpha2 subunit and SHP-1.

• Authors: Alexander Nyström, Zabeena P Shaik, Donald Gullberg, Thomas Krieg, Beate Eckes, Roy Zent, Ambra Pozzi, Renato V Iozzo
• Journal: Blood (Blood) Vol. 114 Issue 23 Pg. 4897-906 (Nov 26 2009) ISSN: 1528-0020 [Electronic] United States
• PMID: 19789387 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Heparan Sulfate Proteoglycans
• Integrin alpha1
• Integrin alpha2beta1
• Peptide Fragments
• Recombinant Fusion Proteins
• perlecan
• Phosphotyrosine
• Receptor Protein-Tyrosine Kinases
• PTPN6 protein, human
• Protein Tyrosine Phosphatase, Non-Receptor Type 6
• Ptpn6 protein, mouse

Topics

• Animals
• Carcinoma, Lewis Lung (blood supply)
• Cell Adhesion (drug effects)
• Endothelium, Vascular (physiology)
• Heparan Sulfate Proteoglycans (pharmacology, physiology)
• Humans
• Integrin alpha1 (genetics)
• Integrin alpha2beta1 (chemistry, deficiency, genetics, metabolism)
• Mice
• Mice, Inbred C57BL
• Mice, Knockout
• Neovascularization, Pathologic (drug therapy)
• Neovascularization, Physiologic (physiology)
• Peptide Fragments (pharmacology, physiology)
• Phosphorylation (drug effects)
• Phosphotyrosine (analysis)
• Protein Interaction Mapping
• Protein Processing, Post-Translational (drug effects)
• Protein Structure, Tertiary
• Protein Tyrosine Phosphatase, Non-Receptor Type 6 (chemistry, deficiency, metabolism, physiology)
• Receptor Protein-Tyrosine Kinases (antagonists & inhibitors, physiology)
• Recombinant Fusion Proteins (physiology)
• Xenograft Model Antitumor Assays