Allosteric peptide activators of pro-hepatocyte growth factor stimulate Met signaling

J Biol Chem. 2010 Dec 17;285(51):40362-72. doi: 10.1074/jbc.M110.179721. Epub 2010 Oct 11.

Abstract

Hepatocyte growth factor (HGF) binds to its target receptor tyrosine kinase, Met, as a single-chain form (pro-HGF) or as a cleaved two-chain disulfide-linked α/β-heterodimer. However, only two-chain HGF stimulates Met signaling. Proteolytic cleavage of the Arg(494)-Val(495) peptide bond in the zymogen-like pro-HGF results in allosteric activation of the serine protease-like β-chain (HGF β), which binds Met to initiate signaling. We use insights from the canonical trypsin-like serine protease activation mechanism to show that isolated peptides corresponding to the first 7-10 residues of the cleaved N terminus of the β-chain stimulate Met phosphorylation by pro-HGF to levels that are ∼25% of those stimulated by two-chain HGF. Biolayer interferometry data demonstrate that peptide VVNGIPTR (peptide V8) allosterically enhances pro-HGF β binding to Met, resulting in a K(D)(app) of 1.6 μm, only 8-fold weaker than the Met/HGF β-chain affinity. Most notably, in vitro cell stimulation with peptide V8 in the presence of pro-HGF leads to Akt phosphorylation, enhances cell survival, and facilitates cell migration between 75 and 100% of that found with two-chain HGF, thus revealing a novel approach for activation of Met signaling that bypasses proteolytic processing of pro-HGF. Peptide V8 is unable to enhance Met binding or signaling with HGF proteins having a mutated activation pocket (D672N). Furthermore, Gly substitution of the N-terminal Val residue in peptide V8 results in loss of all activity. Overall, these findings identify the activation pocket of the serine protease-like β-chain as a "hot spot" for allosteric regulation of pro-HGF and have broad implications for developing selective allosteric activators of serine proteases and pseudoproteases.

MeSH terms

  • Allosteric Regulation / drug effects
  • Allosteric Regulation / physiology
  • Amino Acid Substitution
  • Animals
  • CHO Cells
  • Cell Survival / drug effects
  • Cell Survival / physiology
  • Cricetinae
  • Cricetulus
  • Hepatocyte Growth Factor / genetics
  • Hepatocyte Growth Factor / metabolism*
  • Humans
  • Mutation, Missense
  • Oligopeptides / metabolism*
  • Oligopeptides / pharmacology
  • Phosphorylation / drug effects
  • Phosphorylation / physiology
  • Protein Binding / drug effects
  • Protein Binding / physiology
  • Protein Precursors / genetics
  • Protein Precursors / metabolism*
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism
  • Proto-Oncogene Proteins c-met / genetics
  • Proto-Oncogene Proteins c-met / metabolism*
  • Receptors, Growth Factor / genetics
  • Receptors, Growth Factor / metabolism*
  • Serine Proteases / genetics
  • Serine Proteases / metabolism
  • Signal Transduction / drug effects
  • Signal Transduction / physiology*

Substances

  • HGF protein, human
  • Oligopeptides
  • Protein Precursors
  • Receptors, Growth Factor
  • pro-hepatocyte growth factor
  • Hepatocyte Growth Factor
  • MET protein, human
  • Proto-Oncogene Proteins c-met
  • Proto-Oncogene Proteins c-akt
  • Serine Proteases