Role of PECAM-1 in the shear-stress-induced activation of Akt and the endothelial nitric oxide synthase (eNOS) in endothelial cells.
The application of fluid shear stress to endothelial cells elicits the formation of nitric oxide (NO) and phosphorylation of the endothelial NO synthase (eNOS). Shear stress also elicits the enhanced tyrosine phosphorylation of endothelial proteins, especially of those situated in the vicinity of cell-cell contacts. Since a major constituent of these endothelial cell-cell contacts is the platelet endothelial cell adhesion molecule-1 (PECAM-1) we assessed the role of PECAM-1 in the activation of eNOS. In human endothelial cells, shear stress induced the tyrosine phosphorylation of PECAM-1 and enhanced the association of PECAM-1 with eNOS. Endothelial cell stimulation with shear stress elicited the phosphorylation of Akt and eNOS as well as of the AMP-activated protein kinase (AMPK). While the shear-stress-induced tyrosine phosphorylation of PECAM-1 as well as the serine phosphorylation of Akt and eNOS were abolished by the pre-treatment of cells with the tyrosine kinase inhibitor PP1 the phosphorylation of AMPK was unaffected. Down-regulation of PECAM-1 using a siRNA approach attenuated the shear-stress-induced phosphorylation of Akt and eNOS, as well as the shear-stress-induced accumulation of cyclic GMP levels while the shear-stress-induced phosphorylation of AMPK remained intact. A comparable attenuation of Akt and eNOS (but not AMPK) phosphorylation and NO production was also observed in endothelial cells generated from PECAM-1-deficient mice. These data indicate that the shear-stress-induced activation of Akt and eNOS in endothelial cells is modulated by the tyrosine phosphorylation of PECAM-1 whereas the shear-stress-induced phosphorylation of AMPK is controlled by an alternative signaling pathway.
Fleming
Ingrid
I
Institut für Kardiovaskuläre Physiologie, Johann Wolfgang Goethe-Universität, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany. fleming@em.uni-frankfurt.de
Fisslthaler
Beate
B
Dixit
Madhulika
M
Busse
Rudi
R
D055372:AMP-Activated Protein Kinases; D000818:Animals; D000081247:CSK Tyrosine-Protein Kinase; D002478:Cells, Cultured; D042783:Endothelial Cells / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D004789:Enzyme Activation; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D009097:Multienzyme Complexes / Q000378:metabolism; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism*; D010766:Phosphorylation; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000378:metabolism; D033081:Shear Strength; D013314:Stress, Mechanical; D019061:src-Family Kinases
D009097:Multienzyme Complexes; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D034741:RNA, Small Interfering; D052250:Nitric Oxide Synthase Type III; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; C000631346:CSK protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D055372:AMP-Activated Protein Kinases