HaCaT keratinocyte migration is dependent on epidermal growth factor receptor signaling and glycogen synthase kinase-3α

After epithelial disruption by tissue injury, keratinocytes migrate from the wound edge into a provisional matrix. This process is stimulated by growth factors that signal through epidermal growth factor (EGF) receptor, including EGF, heparin-binding EGF-like growth factor (HB-EGF) and transforming growth factor-α (TGF-α), and by for example keratinocyte growth factor (KGF) and TGF-β1 that function through different receptors. We have previously shown that keratinocyte migration induced by EGF or staurosporine is dependent on the activity of glycogen synthase kinase-3 (GSK-3). In the present study, we show that keratinocyte migration induced by TGF-β1, KGF, EGF, TGF-α and staurosporine depends on EGFR signaling, involves autocrine HB-EGF expression and is potently blocked by GSK-3 inhibitors SB-415286 and LiCl. Inhibition of GSK-3 also retards wound reepithelialization in vivo in mice. Moreover, inhibition of GSK-3 activity prevented cell rounding that is an early event in EGFR-mediated keratinocyte migration. Isoform-specific GSK-3α and GSK-3β knockdown and overexpression experiments with siRNAs and adenoviral constructs, respectively, revealed that GSK-3α is required for keratinocyte migration, whereas excessive activity of GSK-3β is inhibitory. Thus, induction of keratinocyte migration is conveyed through EGFR, promoted by endogenous HB-EGF and requires GSK-3α activity.