The fibrinolytic receptor for urokinase activates the G protein-coupled chemotactic receptor FPRL1/LXA4R.
The function of urokinase and its receptor is essential for cell migration in pathological conditions, as shown by the analysis of knockout mice phenotypes. How a protease of a fibrinolytic pathway can induce migration is not understood and no link between this protease and migration-promoting G protein-coupled receptors has been described. We now show that FPRL1/LXA4R, a G protein-coupled receptor for a number of polypeptides and for the endogenous lipoxin A4 (LXA4), is the link between urokinase-type plasminogen activator (uPA) and migration as it directly interacts with an activated, soluble, cleaved form of uPA receptor (uPAR) (D2D3(88-274)) to induce chemotaxis. In this article we show that (i) both uPAR and FPRL1/LXA4R are necessary for the chemotactic activity of uPA whereas FPRL1/LXA4R is sufficient to mediate D2D3(88-274)-induced cell migration. (ii) Inhibition or desensitization of FPRL1/LXA4R by antibodies or specific ligands specifically prevents chemotaxis induced by D2D3(88-274) in THP-1 cells and human peripheral blood monocytes. (iii) Desensitization of FPRL1/LXA4R prevents the activation of tyrosine kinase Hck induced by D2D3(88-274). (iv) D2D3(88-274) directly binds to FPRL1/LXA4R and is competed by two specific FPRL1/LXA4R agonists, the synthetic MMK-1 peptide and a stable analog of LXA4. Thus, a naturally produced cleaved form of uPAR is a unique endogenous chemotactic agonist for FPRL1/LXA4R receptor and its activity can be antagonized by specific ligands. These results provide the first direct link, to our knowledge, between the fibrinolytic machinery and the inflammatory response, demonstrating that uPA-derived peptide fragments can activate a specific chemotactic receptor.
Resnati
M
M
Molecular Genetics Unit, Department of Cell Biology and Functional Genomics, DIBIT-Istituto Scientifico San Raffaele and Università Vita-Salute San Raffaele, Via Olgettina 58, 20132 Milano, Italy.
Pallavicini
I
I
Wang
J M
JM
Oppenheim
J
J
Serhan
C N
CN
Romano
M
M
Blasi
F
F
D000818:Animals; D002460:Cell Line; D002634:Chemotaxis, Leukocyte / Q000187:drug effects / Q000502:physiology; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D006893:Hydroxyeicosatetraenoic Acids / Q000378:metabolism; D015471:Leukemia, Basophilic, Acute; D044045:Lipoxins; D009000:Monocytes / Q000502:physiology; D009240:N-Formylmethionine Leucyl-Phenylalanine / Q000494:pharmacology; D010455:Peptides / Q000494:pharmacology; D010960:Plasminogen Activators / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D011956:Receptors, Cell Surface / Q000378:metabolism*; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic / Q000502:physiology*; D044067:Receptors, Lipoxin; D018000:Receptors, Peptide / Q000502:physiology*; D055293:Receptors, Urokinase Plasminogen Activator; D014407:Tumor Cells, Cultured; D014568:Urokinase-Type Plasminogen Activator / Q000378:metabolism
C105101:FPR2 protein, human; D006893:Hydroxyeicosatetraenoic Acids; D044045:Lipoxins; C408903:MMK-1 peptide; C524898:PLAUR protein, human; D010455:Peptides; C524899:Plaur protein, mouse; C524900:Plaur protein, rat; D011956:Receptors, Cell Surface; D044042:Receptors, Formyl Peptide; D011971:Receptors, Immunologic; D044067:Receptors, Lipoxin; D018000:Receptors, Peptide; D055293:Receptors, Urokinase Plasminogen Activator; C040527:lipoxin A4; D009240:N-Formylmethionine Leucyl-Phenylalanine; D011505:Protein-Tyrosine Kinases; D010960:Plasminogen Activators; D014568:Urokinase-Type Plasminogen Activator; D019204:GTP-Binding Proteins