title: Shear stress activates Tie2 receptor tyrosine kinase in human endothelial cells.
abstract: The receptor tyrosine kinase (RTK) Tie2 is expressed predominantly on endothelial cells. Tie2 is critical for vasculogenesis during development and could be important for maintaining endothelial cell survival and integrity in adult blood vessels. Although most RTKs are activated by shear stress in the absence of ligand activation, the effect of shear stress on Tie2 is unknown. Therefore, we examined the effect of shear stress on Tie2 phosphorylation in primary cultured endothelial cells. Interestingly, shear stress (20 dyne/cm(2)) produced a rapid, marked, and sustained Tie2 phosphorylation, while it produced a rapid but slight and transient phosphorylation of insulin receptor and VEGF receptor 2 (Flk1). In addition, Tie2 phosphorylation in response to shear stress was velocity-dependent, while phosphorylation of insulin receptor and Flk1 was not. Shear stress also produced Akt phosphorylation in a time-, velocity-, and PI 3-kinase-dependent manner. Accordingly, shear stress suppressed serum deprivation-induced endothelial cell apoptosis. Taken together, our results indicated that activation of Tie2/PI 3-kinase/Akt in response to shear stress could be an important signaling cascade for maintaining endothelial survival and integrity in blood vessels.
authors.affiliation: National Creative Research Initiatives Center for Endothelial Cells and Division of Molecular and Life Sciences, Pohang University of Science and Technology, Pohang, 790-784, Republic of Korea. gykoh@postech.ac.kr
authors.forename: Hyuek Jong
authors.initials: HJ
authors.lastname: Lee
authors.forename: Gou Young
authors.initials: GY
authors.lastname: Koh
mesh_terms: D017209:Apoptosis; D002478:Cells, Cultured; D004730:Endothelium, Vascular / Q000166:cytology / Q000201:enzymology*; D004789:Enzyme Activation; D006801:Humans; D007700:Kinetics; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D011972:Receptor, Insulin / Q000378:metabolism; D042787:Receptor, TIE-2; D013314:Stress, Mechanical; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism
chemical_list: D011518:Proto-Oncogene Proteins; D020794:Receptor Protein-Tyrosine Kinases; D011972:Receptor, Insulin; D042787:Receptor, TIE-2; D040301:Vascular Endothelial Growth Factor Receptor-2; C494918:AKT1 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt