title: Evidence for a role of platelet endothelial cell adhesion molecule-1 in endothelial cell mechanosignal transduction: is it a mechanoresponsive molecule?
abstract: Fluid shear stress (FSS) induces many forms of responses, including phosphorylation of extracellular signal-regulated kinase (ERK) in endothelial cells (ECs). We have earlier reported rapid tyrosine phosphorylation of platelet endothelial cell adhesion molecule-1 (PECAM-1) in ECs exposed to FSS. Osmotic changes also induced similar PECAM-1 and ERK phosphorylation with nearly identical kinetics. Because both FSS and osmotic changes should mechanically perturb the cell membrane, they might activate the same mechanosignaling cascade. When PECAM-1 is tyrosine phosphorylated by FSS or osmotic changes, SHP-2 binds to it. Here we show that ERK phosphorylation by FSS or osmotic changes depends on PECAM-1 tyrosine phosphorylation, SHP-2 binding to phospho-PECAM-1, and SHP-2 phosphatase activity. In ECs under flow, detectable amounts of SHP-2 and Gab1 translocated from the cytoplasm to the EC junction. When magnetic beads coated with antibodies against the extracellular domain of PECAM-1 were attached to ECs and tugged by magnetic force for 10 min, PECAM-1 associated with the beads was tyrosine phosphorylated. ERK was also phosphorylated in these cells. Binding of the beads by itself or pulling on the cell surface using poly-l-coated beads did not induce phosphorylation of PECAM-1 and ERK. These results suggest that PECAM-1 is a mechanotransduction molecule.
authors.affiliation: Department of Structural Analysis, National Cardiovascular Center Research Institute, Osaka 565-8565, Japan.
authors.forename: Masaki
authors.initials: M
authors.lastname: Osawa
authors.forename: Michitaka
authors.initials: M
authors.lastname: Masuda
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Kusano
authors.forename: Keigi
authors.initials: K
authors.lastname: Fujiwara
mesh_terms: D000818:Animals; D002417:Cattle; D002448:Cell Adhesion / Q000502:physiology; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology*; D004789:Enzyme Activation; D007365:Intercellular Junctions / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009994:Osmolar Concentration; D010750:Phosphoproteins / Q000378:metabolism; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000502:physiology*; D021381:Protein Transport / Q000502:physiology; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D013314:Stress, Mechanical
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D010750:Phosphoproteins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D020928:Mitogen-Activated Protein Kinases; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D017027:Protein Tyrosine Phosphatases