title: Binding of urokinase to low density lipoprotein-related receptor (LRP) regulates vascular smooth muscle cell contraction.
abstract: Urokinase plasminogen activator (uPA) is a multifunctional protein that has been implicated in several physiological and pathological processes involving cell adhesion and migration in addition to fibrinolysis. In a previous study we found that two-chain urokinase plasminogen activator (tcuPA) stimulates phenylephrine-induced vasoconstriction of isolated rat aortic rings. In the present paper we report that uPA(-/-) mice have a significantly lower mean arterial blood pressure than do wild type mice and that aortic rings from uPA(-/-) mice show an attenuated contractile response to phenylephrine. In contrast, the blood pressure of urokinase receptor knockout (uPAR(-/-)) mice and the response of their isolated aortic rings to phenylephrine were normal, indicating that the effect of uPA on vascular contraction is independent of uPAR. Addition of mouse and human uPA almost completely reversed both the impaired vascular contractility and the lower arterial blood pressure in vivo. The in vitro and in vivo effects of infused uPA on aortic contractility and the restoration of normal blood pressure in uPA(-/-) mice were prevented by antibody to low-density lipoprotein receptor-related protein/alpha(2)-macroglobulin receptor (LRP). A modified form of uPA that lacks the kringle failed to restore the blood pressure in uPA(-/-) mice, notwithstanding having a longer half-life in the circulation. Ligands that regulate the interaction of uPA with LRP, such as PAI-1 or the PAI-1-derived peptide (EEIIMD), abolished the vasoactivity of tcuPA in vitro and in vivo. These studies identify a novel signal transducing cellular receptor pathway involved in the regulation of vascular contractility.
authors.affiliation: Department of Clinical Biochemistry, Hadassah University Hospital and Hebrew University-Hadassah Medical School, Jerusalem 91120, Israel.
authors.forename: Taher
authors.initials: T
authors.lastname: Nassar
authors.forename: Abdullah
authors.initials: A
authors.lastname: Haj-Yehia
authors.forename: Sa'ed
authors.initials: S
authors.lastname: Akkawi
authors.forename: Alice
authors.initials: A
authors.lastname: Kuo
authors.forename: Khalil
authors.initials: K
authors.lastname: Bdeir
authors.forename: Andrew
authors.initials: A
authors.lastname: Mazar
authors.forename: Douglas B
authors.initials: DB
authors.lastname: Cines
authors.forename: Abd Al-Roof
authors.initials: AA
authors.lastname: Higazi
mesh_terms: D000818:Animals; D001794:Blood Pressure; D066298:In Vitro Techniques; D026503:Low Density Lipoprotein Receptor-Related Protein-1 / Q000378:metabolism / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000378:metabolism; D011485:Protein Binding; D011956:Receptors, Cell Surface / Q000235:genetics / Q000502:physiology; D055293:Receptors, Urokinase Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism*; D014661:Vasoconstriction / Q000502:physiology
chemical_list: D026503:Low Density Lipoprotein Receptor-Related Protein-1; C524898:PLAUR protein, human; C524899:Plaur protein, mouse; C524900:Plaur protein, rat; D011956:Receptors, Cell Surface; D055293:Receptors, Urokinase Plasminogen Activator; D014568:Urokinase-Type Plasminogen Activator