Heparin-Binding EGF-Like Growth Factor Is Induced by Disruption of Lipid Rafts and Oxidative Stress in Keratinocytes and Participates in the Epidermal Response to Cutaneous Wounds

Abstract

Epidermal homeostasis and repair of the skin barrier require that epidermal keratinocytes respond to alterations of their environment. We report that cellular stress with methyl-beta-cyclodextrin (MBCD), a molecule that extracts membrane cholesterol and thereby disrupts the structure of lipid rafts, strongly induces the synthesis of heparin-binding EGF-like growth factor (HB-EGF) in keratinocytes through the activation of p38 mitogen-activated protein kinase. Interesting parallels between lipid raft disruption and oxidative stress can be drawn as hydrogen peroxide induces p38 activation and HB-EGF synthesis in keratinocytes. Consistent with other studies, we show increased HB-EGF expression in keratinocytes located at the margin of wounded skin areas. Analyzing cultured keratinocytes exposed to rhHB-EGF, we report increased HB-EGF mRNA levels and alterations in the expression of differentiation markers. Interestingly, identical alterations in differentiation markers are shown to occur in vivo at the wound margin and in HB-EGF-treated cultures. In addition, in vitro sectioning of skin samples also induces the expression of HB-EGF at the border of the incisions. Altogether, our data suggest that expression of HB-EGF is a marker of the keratinocyte's response to a challenging environment and demonstrate that this growth factor alters the phenotype of keratinocytes in a manner similar to that observed during epidermal repair.

Epidermal Hyperplasia and Elevated HB-EGF are More Prominent in Retinoid Dermatitis Compared with Irritant Contact Dermatitis Induced by Benzalkonium Chloride

“…ester and various other stress stimuli on cultured cells are able to induce HB-EGF mRNA levels and the shedding of proHB-EGF into soluble HB-EGF 26 . In addition to EGF, IL-8 is also active as a mitogen for epithelial and endothelial cell proliferation 26 .…”

“…In addition to EGF, IL-8 is also active as a mitogen for epithelial and endothelial cell proliferation 26 .…”

Studies of cell signaling in a reconstructed human epidermis exposed to sensitizers: IL-8 synthesis and release depend on EGFR activation

“…Since MAPK p38 plays major roles in cellular responses to environmental and physiological stresses [14,15,20,32] and MAPK ERK 1/2 promotes cellular proliferation needed for tissue reconstruction [24], phosphorylation of both MAPK's was investigated in our model. RHE was exposed for 1, 2, 4, 8 or 22 h to DNFB (0.250 mg/ml) as a prototype sensitizing chemical, then tissue extracts were analyzed by Western blot in order to detect phosphorylated forms of p38 and ERK 1/2 MAPK's (Fig.…”

Infrared microscopic imaging of cutaneous wound healing: lipid conformation in the migrating epithelial tongue

“…25,26 Of interest in the current work is the possible role of the physical state of lipid in the receptor environment on the control of EGFR function. Several studies addressing this issue have suggested receptor localization in lipid rafts, [17][18][19][20]27 cholesterol enriched domains involved in signal transduction. Pike et al 17 reported that the EGFR-enriched lipid rafts are augmented in lipid classes that differ from those identified by the classical Triton X-100 extraction procedure that first defined lipid rafts.…”

“…The initially impaired barrier was restored to near normal at six months postgrafting. In additional studies by several groups over the past decade, [17][18][19][20] the putative role of lipid rafts in controlling the function of cell signaling molecules, involving the epidermal growth factor receptor (EGFR), has been investigated through biochemical and molecular approaches. EGFR controls keratinocyte proliferation and motility.…”