Tyrosine phosphatase beta regulates angiopoietin-Tie2 signaling in human endothelial cells

OK Yacyshyn, PFH Lai, K Forse… - Angiogenesis, 2009 - Springer
OK Yacyshyn, PFH Lai, K Forse, K Teichert-Kuliszewska, P Jurasz, DJ Stewart
Angiogenesis, 2009•Springer
Objectives The endothelial cell (EC)-selective receptor tyrosine kinase, Tie2, and its ligands
angiopoietin Ang-1 and Ang-2, are essential for blood vessel maintenance and repair. Ang-
1 is an agonist of Tie2 receptor activation, whereas Ang-2 is a context-dependent
antagonist/agonist. Therefore, we investigated the role of the EC-selective phosphatase,
human protein tyrosine phosphatase beta (HPTPβ), in regulating Tie2 activity. Methods and
results siRNA silencing of HPTPβ enhanced Ang-1 and Ang-2-induced Tie2 …
Objectives
The endothelial cell (EC)-selective receptor tyrosine kinase, Tie2, and its ligands angiopoietin Ang-1 and Ang-2, are essential for blood vessel maintenance and repair. Ang-1 is an agonist of Tie2 receptor activation, whereas Ang-2 is a context-dependent antagonist/agonist. Therefore, we investigated the role of the EC-selective phosphatase, human protein tyrosine phosphatase beta (HPTPβ), in regulating Tie2 activity.
Methods and results
siRNA silencing of HPTPβ enhanced Ang-1 and Ang-2-induced Tie2 phosphorylation at 10 min (2.5-fold, P < 0.001; and 1.8-fold, P < 0.05, respectively). The cell survival response to Ang-1, but not Ang-2, was enhanced by HPTPβ silencing as measured by flow cytometry (0.85-fold to 0.66-fold, P < 0.05) and ELISA (0.88-fold to 0.53-fold, P < 0.01). Hypoxia, which upregulated HPTPβ expression in endothelial cells, impaired Ang-1-induced Tie2 phosphorylation.
Conclusions
These results reveal a novel role for HPTPβ in modulating Ang-1-Tie2 signaling and endothelial cell survival.
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