uPAR-deficient mouse keratinocytes fail to produce EGFR-dependent laminin-5, affecting migration in vivo and in vitro.
The urokinase receptor (uPAR) is involved in a series of pathological processes, from inflammation to cancer. We have analyzed in detail the role of uPAR and the mechanisms involved in keratinocyte behavior during wound healing by exploiting uPAR-knockout (KO) mice. In vivo, uPAR-KO mice showed delayed wound healing, with abnormal keratinocyte migration and proliferation. In vitro, unlike wild-type cells, primary uPAR-KO keratinocytes did not proliferate in response to epidermal growth factor (EGF), their growth and migration were not inhibited by EGF-receptor (EGFR) inhibitors, and they did not adhere to uncoated surfaces. Whereas EGFR levels in uPAR-KO keratinocytes were normal, there was no tyrosine phosphorylation upon addition of EGF, and its downstream targets, extracellular-signal-regulated kinases 1 and 2 (ERK1/2), were not activated. Re-introduction of mouse uPAR rescued all phenotypes. In vitro adhesion and migration defects were associated with the failure of uPAR-KO keratinocytes to normally produce and secrete laminin-5 (LN5), an event that requires EGFR signaling. These results were confirmed in vivo, with LN5 being upregulated during wound healing in wild-type but not in uPAR-KO epidermis.
D'Alessio
Silvia
S
Università Vita Salute San Raffaele and Istituto Scientifico H San Raffaele, via Olgettina 60, 20132 Milano, Italy.
Gerasi
Laura
L
Blasi
Francesco
F
D000818:Animals; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D002465:Cell Movement; D049109:Cell Proliferation; D004815:Epidermal Growth Factor / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D055293:Receptors, Urokinase Plasminogen Activator / Q000235:genetics* / Q000378:metabolism; D014945:Wound Healing / Q000235:genetics; D000097794:Kalinin
D015815:Cell Adhesion Molecules; D004815:Epidermal Growth Factor; D055293:Receptors, Urokinase Plasminogen Activator; D000097794:Kalinin