Alternative proteolytic processing of hepatocyte growth factor during wound repair.
Wound healing is a crucial regenerative process in all organisms. We examined expression, integrity, and function of the proteins in the hepatocyte growth factor (HGF)/c-Met signaling pathway in normally healing and non-healing human skin wounds. Whereas in normally healing wounds phosphorylation of c-Met was most prominent in keratinocytes and dermal cells, in non-healing wounds phosphorylation of c-Met was barely detectable, suggesting reduced c-Met activation. In wound exudates obtained from non-healing, but not from healing wounds, HGF protein was a target of substantial proteolytic processing that was different from the classical activation by known serine proteases. Western blot analysis and protease inhibitor studies revealed that HGF is a target of neutrophil elastase and plasma kallikrein during skin repair. Proteolytic processing of HGF by each of these proteases significantly attenuated keratinocyte proliferation, wound closure capacity in vitro, and c-Met signal transduction. Our findings reveal a novel pathway of HGF processing during skin repair. Conditions in which proteases are imbalanced and tend toward increased proteolytic activity, as in chronic non-healing wounds, might therefore compromise HGF activity due to the inactivation of the HGF protein and/or the generation of HGF fragments that ultimately mediate a dominant negative effect and limit c-Met activation.
Buchstein
Nils
N
Professor of Dermatology, Department of Dermatology, University of Cologne, Joseph-Stelzmann Str. 9, 50931 Köln, Germany.
Hoffmann
Daniel
D
Smola
Hans
H
Lang
Sabina
S
Paulsson
Mats
M
Niemann
Catherin
C
Krieg
Thomas
T
Eming
Sabine A
SA
D000368:Aged; D015153:Blotting, Western; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005122:Exudates and Transudates / Q000737:chemistry; D017228:Hepatocyte Growth Factor / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D015603:Keratinocytes / Q000378:metabolism; D010766:Phosphorylation; D019859:Proto-Oncogene Proteins c-met / Q000378:metabolism; D012697:Serine Endopeptidases / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D012867:Skin / Q000378:metabolism; D014945:Wound Healing / Q000502:physiology*
D017228:Hepatocyte Growth Factor; D019859:Proto-Oncogene Proteins c-met; D012697:Serine Endopeptidases