title: Ca2+ and UVB radiation have no effect on E-cadherin-mediated melanocyte-keratinocyte adhesion.
abstract: Direct cell-cell contact between melanocytes and keratinocytes has been shown to play an important role in the regulation of human melanocyte function and skin pigmentation. An important role for the calcium-dependent epithelium-specific cell adhesion molecule, E-cadherin, in melanocyte-keratinocyte adhesion was suggested previously. To further clarify regulation of E-cadherin-mediated melanocyte-keratinocyte interactions, we investigated the effects of physiological (Ca2+) and environmental (ultraviolet B [UVB] radiation) stimuli on the expression and functional activity of E-cadherin in melanocyte-keratinocyte adhesion. Expression of E-cadherin mRNA was detected by Northern blot analysis in cultured normal human melanocytes at levels similar to those in keratinocytes. Flow cytometry analysis with anti-human and anti-mouse-E-cadherin antibodies (anti-uvomorulin and ECCD-2) showed that cultured normal human keratinocytes, melanocytes, and two metastatic melanoma cell lines express E-cadherin strongly on the cell surfaces. Melanocyte adhesion, particularly to differentiating keratinocytes (cultured in 1.2 mM calcium) but not to proliferating keratinocytes or to fibroblasts, was decreased by 41.7 +/- 4.5% in the absence of 1 mM Ca2+ during the binding assay. Addition of anti-mouse-E-cadherin antibody (ECCD-1) to the binding assay inhibited the adhesion of melanocytes to differentiating keratinocytes by 88.2 +/- 1.1%, while addition of anti-P-cadherin antibody (PCD-1) had no effect. The levels of E-cadherin expression in melanocytes were not changed by the presence of calcium (1 mM) in the medium or by UVB irradiation (20 mJ/cm2) for one day before flow cytometry analysis. Moreover, these treatments had no effect on melanocyte-keratinocyte adhesion. These results demonstrate that E-cadherin is strongly involved in melanocyte adhesion to keratinocytes and suggest the implication of E-cadherin in the overall regulation of the skin pigmentary system.
authors.affiliation: Skin Substitute Laboratory, CNRS-URA 1341, Lyon, France.
authors.forename: K
authors.initials: K
authors.lastname: Nakazawa
authors.forename: H
authors.initials: H
authors.lastname: Nakazawa
authors.forename: M
authors.initials: M
authors.lastname: Bonnard
authors.forename: O
authors.initials: O
authors.lastname: Damour
authors.forename: C
authors.initials: C
authors.lastname: Collombel
mesh_terms: D000328:Adult; D015152:Blotting, Northern; D015820:Cadherins / Q000502:physiology*; D002118:Calcium / Q000494:pharmacology*; D002448:Cell Adhesion / Q000187:drug effects / Q000528:radiation effects; D002478:Cells, Cultured; D005434:Flow Cytometry; D006801:Humans; D015603:Keratinocytes / Q000166:cytology*; D008297:Male; D008544:Melanocytes / Q000166:cytology*; D008545:Melanoma; D014407:Tumor Cells, Cultured; D014466:Ultraviolet Rays
chemical_list: D015820:Cadherins; D002118:Calcium