Extracellular proteolytic cleavage by urokinase is required for activation of hepatocyte growth factor/scatter factor

EMBO J. 1992 Dec;11(13):4825-33.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cells, Cultured
  • Electrophoresis, Polyacrylamide Gel
  • Extracellular Matrix / drug effects
  • Extracellular Matrix / metabolism
  • Hepatocyte Growth Factor / metabolism*
  • Humans
  • Hydrolysis
  • Protein Processing, Post-Translational
  • Protein-Tyrosine Kinases / metabolism
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-met
  • Receptors, Cell Surface / metabolism
  • Serine Proteinase Inhibitors / pharmacology
  • Tumor Cells, Cultured
  • Urokinase-Type Plasminogen Activator / antagonists & inhibitors
  • Urokinase-Type Plasminogen Activator / metabolism*

Substances

  • Proto-Oncogene Proteins
  • Receptors, Cell Surface
  • Serine Proteinase Inhibitors
  • Hepatocyte Growth Factor
  • Protein-Tyrosine Kinases
  • Proto-Oncogene Proteins c-met
  • Urokinase-Type Plasminogen Activator