title: Hydrogen peroxide activates the Gas6-Axl pathway in vascular smooth muscle cells.
abstract: Axl, a receptor tyrosine kinase, is involved in cell survival, proliferation, and migration. We have shown that Axl expression increases in the neointima of balloon-injured rat carotids. Because oxidative stress is known to play a major role in remodeling of injured vessels, we hypothesized that H(2)O(2) might activate Axl by promoting autophosphorylation. H(2)O(2) rapidly stimulated Axl tyrosine phosphorylation in rat vascular smooth muscle cells within 1 min that was maximal at 5 min (6-fold). The response to H(2)O(2) was concentration-dependent with EC(50) of approximately 500 microm. Axl phosphorylation was partly dependent on production of its endogenous ligand, growth arrest gene 6 (Gas6), because Axl-Fc, a fragment of Axl extracellular domain that neutralizes Gas6, inhibited H(2)O(2)-induced Axl phosphorylation by 50%. Axl phosphorylation by H(2)O(2) was also attenuated by warfarin, which inhibits Gas6 activity by preventing post-translational modification. In intact vessels Axl was phosphorylated by H(2)O(2), and Axl phosphorylation was inhibited by warfarin treatment in balloon-injured carotids. Akt, a downstream target of Axl, was phosphorylated by H(2)O(2)in Axl(+/+) mouse aorta but significantly inhibited in Axl(-/-) aorta. Intimal proliferation was decreased significantly in a cuff injury model in Axl(-/-) mice compared with Axl(+/+) mice. In summary, Axl is an important signaling mediator for oxidative stress in cultured vascular smooth muscle cells and intact vessels and may represent an important therapeutic target for vascular remodeling and response to injury.
authors.affiliation: Center for Cardiovascular Research, University of Rochester, 601 Elmwood Avenue, Rochester, NY 14642, USA.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Konishi
authors.forename: Toru
authors.initials: T
authors.lastname: Aizawa
authors.forename: Amy
authors.initials: A
authors.lastname: Mohan
authors.forename: Vyacheslav A
authors.initials: VA
authors.lastname: Korshunov
authors.forename: Bradford C
authors.initials: BC
authors.lastname: Berk
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002455:Cell Division; D002465:Cell Movement; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005263:Femoral Artery / Q000473:pathology; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology*; D015151:Immunoblotting; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D008024:Ligands; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D015513:Oncogene Proteins / Q000378:metabolism*; D018384:Oxidative Stress; D010766:Phosphorylation; D011233:Precipitin Tests; D011518:Proto-Oncogene Proteins; D051381:Rats; D017207:Rats, Sprague-Dawley; D020794:Receptor Protein-Tyrosine Kinases / Q000378:metabolism*; D013997:Time Factors; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism; D014859:Warfarin / Q000494:pharmacology; D000094963:Axl Receptor Tyrosine Kinase; D000099255:Growth Arrest-Specific Protein 6
chemical_list: D006861:Hydrogen Peroxide; D036341:Intercellular Signaling Peptides and Proteins; D008024:Ligands; D015513:Oncogene Proteins; D011518:Proto-Oncogene Proteins; D020794:Receptor Protein-Tyrosine Kinases; D014443:Tyrosine; D042461:Vascular Endothelial Growth Factor A; D014859:Warfarin; D000094963:Axl Receptor Tyrosine Kinase; D000099255:Growth Arrest-Specific Protein 6