title: PECAM1 regulates flow-mediated Gab1 tyrosine phosphorylation and signaling.
abstract: Endothelial dysfunction, characterized by impaired activation of endothelial nitric oxide (NO) synthase (eNOS) and ensued decrease of NO production, is a common mechanism of various cardiovascular pathologies, including hypertension and atherosclerosis. Laminar blood flow-mediated specific signaling cascades modulate vascular endothelial cells (ECs) structure and functions. We have previously shown that flow-stimulated Gab1 (Grb2-associated binder-1) tyrosine phosphorylation mediates eNOS activation in ECs, which in part confers laminar flow atheroprotective action. However, the molecular mechanisms whereby flow regulates Gab1 tyrosine phosphorylation and its downstream signaling events remain unclear. Here we show that platelet endothelial cell adhesion molecule-1 (PECAM1), a key molecule in an endothelial mechanosensing complex, specifically mediates Gab1 tyrosine phosphorylation and its downstream Akt and eNOS activation in ECs upon flow rather than hepatocyte growth factor (HGF) stimulation. Small interfering RNA (siRNA) targeting PECAM1 abolished flow- but not HGF-induced Gab1 tyrosine phosphorylation and Akt, eNOS activation as well as Gab1 membrane translocation. Protein-tyrosine phosphatase SHP2, which has been shown to interact with Gab1, was involved in flow signaling and HGF signaling, as SHP2 siRNA diminished the flow- and HGF-induced Gab1 tyrosine phosphorylation, membrane localization and downstream signaling. Pharmacological inhibition of PI3K decreased flow-, but not HGF-mediated Gab1 phosphorylation and membrane localization as well as eNOS activation. Finally, we observed that flow-mediated Gab1 and eNOS phosphorylation in vivo induced by voluntary wheel running was reduced in PECAM1 knockout mice. These results demonstrate a specific role of PECAM1 in flow-mediated Gab1 tyrosine phosphorylation and eNOS signaling in ECs.
authors.affiliation: Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
authors.forename: Suowen
authors.initials: S
authors.lastname: Xu
authors.affiliation: Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
authors.forename: Chang Hoon
authors.initials: CH
authors.lastname: Ha
authors.affiliation: Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
authors.forename: Weiye
authors.initials: W
authors.lastname: Wang
authors.affiliation: Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
authors.forename: Xiangbin
authors.initials: X
authors.lastname: Xu
authors.affiliation: Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
authors.forename: Meimei
authors.initials: M
authors.lastname: Yin
authors.affiliation: Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
authors.forename: Felix Q
authors.initials: FQ
authors.lastname: Jin
authors.affiliation: Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Mastrangelo
authors.affiliation: Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
authors.forename: Marina
authors.initials: M
authors.lastname: Koroleva
authors.affiliation: Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA.
authors.forename: Keigi
authors.initials: K
authors.lastname: Fujiwara
authors.affiliation: Aab Cardiovascular Research Institute, Department of Medicine, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA. Electronic address: zheng-gen_jin@urmc.rochester.edu.
authors.forename: Zheng Gen
authors.initials: ZG
authors.lastname: Jin
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D002867:Chromones / Q000494:pharmacology; D017228:Hepatocyte Growth Factor / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D061307:Human Umbilical Vein Endothelial Cells; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009025:Morpholines / Q000494:pharmacology; D052250:Nitric Oxide Synthase Type III / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D014443:Tyrosine / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002867:Chromones; C490897:Gab1 protein, mouse; D009025:Morpholines; D010750:Phosphoproteins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D034741:RNA, Small Interfering; D011994:Recombinant Proteins; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D014443:Tyrosine; D017228:Hepatocyte Growth Factor; D052250:Nitric Oxide Synthase Type III; D051057:Proto-Oncogene Proteins c-akt; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; C516725:Ptpn11 protein, mouse
keywords: Gab1; Laminar flow; PECAM1