Extracellular proteolytic cleavage by urokinase is required for activation of hepatocyte growth factor/scatter factor.
The extracellular protease urokinase is known to be crucially involved in morphogenesis, tissue repair and tumor invasion by mediating matrix degradation and cell migration. Hepatocyte growth factor/scatter factor (HGF/SF) is a secretory product of stromal fibroblasts, sharing structural motifs with enzymes of the blood clotting cascade, including a zymogen cleavage site. HGF/SF promotes motility, invasion and growth of epithelial and endothelial cells. Here we show that HGF/SF is secreted as a single-chain biologically inactive precursor (pro-HGF/SF), mostly found in a matrix-associated form. Maturation of the precursor into the active alpha beta heterodimer takes place in the extracellular environment and results from a serum-dependent proteolytic cleavage. In vitro, pro-HGF/SF was cleaved at a single site by nanomolar concentrations of pure urokinase, generating the active mature HGF/SF heterodimer. This cleavage was prevented by specific urokinase inhibitors, such as plasminogen activator inhibitor type-1 and protease nexin-1, and by antibodies directed against the urokinase catalytic domain. Addition of these inhibitors to HGF/SF responsive cells prevented activation of the HGF/SF precursor. These data show that urokinase acts as a pro-HGF/SF convertase, and suggest that some of the growth and invasive cellular responses mediated by this enzyme may involve activation of HGF/SF.
Naldini
L
L
Department of Biomedical Sciences and Oncology, University of Torino, Italy.
Tamagnone
L
L
Vigna
E
E
Sachs
M
M
Hartmann
G
G
Birchmeier
W
W
Daikuhara
Y
Y
Tsubouchi
H
H
Blasi
F
F
Comoglio
P M
PM
D000818:Animals; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D017228:Hepatocyte Growth Factor / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D011499:Protein Processing, Post-Translational; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019859:Proto-Oncogene Proteins c-met; D011956:Receptors, Cell Surface / Q000378:metabolism; D015842:Serine Proteinase Inhibitors / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014568:Urokinase-Type Plasminogen Activator / Q000037:antagonists & inhibitors / Q000378:metabolism*
D011518:Proto-Oncogene Proteins; D011956:Receptors, Cell Surface; D015842:Serine Proteinase Inhibitors; D017228:Hepatocyte Growth Factor; D011505:Protein-Tyrosine Kinases; D019859:Proto-Oncogene Proteins c-met; D014568:Urokinase-Type Plasminogen Activator