Human keratinocyte membrane lectins: characterization and modulation of their expression by cytokines

Abstract

In an attempt to identify cell surface molecules involved in recognition phenomena between cells such as keratinocytes and melanocytes and putatively target biological responses modifiers to keratinocytes, we undertook the detection of cell surface sugar specific receptors: membrane lectins. Keratinocyte membrane lectins were found to bind synthetic glycoproteins (neoglycoproteins) carrying either alpha-L-fucosyl or alpha-L-rhamnosyl residues. Fluorescence microscopy observations indicate that cultured keratinocytes are able to bind these two neoglycoproteins while frozen sections of human skin labelled with neoglycoprotein-coated covaspheres show that the selectivity of the binding to keratinocytes is restricted to alpha-L-rhamnosyl-BSA. Keratinocytes were adapted to grow on collagen; harvesting conditions allowing the analysis of keratinocytes by flow cytometry are described. This technique allows the quantification of the binding at 4 degrees C, and the estimation of the endocytosis of F-, neoglycoproteins: F-, alpha-L-Rha-BSA and F-, alpha-L-Fuc-BSA were efficiently internalized. Thereafter, alpha-L-rhamnose-substituted liposomes containing 5-(6)carboxyfluorescein were prepared in order to follow the delivery of the fluorescent dye into cells. This was measured both by flow cytometry and by spectrofluorimetry. The expression of surface lectins was checked upon action of cytokines (IL1 alpha, IL1 beta, IL2 and TNF) which are known as biological response modifiers of keratinocytes.

Nuclear presence of adhesion-/growth-regulatory galectins in normal/malignant cells of squamous epithelial origin

“…If separate from the carbohydrate-binding site, the question on interplay between the two sites will have to be resolved. Looking beyond galectins, experiments with neoglycoproteins document the presence of sugar receptors on keratinocytes, cells of the SCL-1 squamous carcinoma cell line and sections of squamous cell carcinomas with specificities to galactose-6-phosphate, a-L-rhamnose or a-L-fucose, broadening the scope of analysis of lectins in this cell system (Gabius et al 1990;Cerdan et al 1991;Condaminet et al 1997;Minwalla et al 2001;Szolnoky et al 2001). Their biochemical characterization will add to the panel of markers, because activities were found to be UV-B inducible, regulatable by cytokines or partaking in melanosome transfer.…”

Physicochemical characterization of a ouabain isomer isolated from bovine hypothalamus.

“…Rhamnose, commonly found as a glycoconjugate in plants and enteric bacteria, is readily available to mammals from dietary and environmental sources. The ubiquitous presence of this sugar may also explain detection of rhamnose-selective lectins in mammalian cells (21). While identification of L-rhamnose does not rule out the possibility that HIF is an endogenous substance, it also does not distinguish HIF from ouabain.…”

Upregulation of TNF-α Production by IFN-γ and LPS in Cultured Canine Keratinocytes: Application to Monosaccharides Effects

“…These cells constitute a major barrier between the internal organism and the external environment and represent 95% of the total epidermal cells. Studies on human keratinocytes and on laboratory rodents have shown that many exogenous and endogenous factors can lead to cutaneous epidermal cell activation (Caughman et al, 1990;Cerdan et al, 1991). Skin exposure to ultraviolet radiation, viral infections, irritants and allergens can induce keratinocyte activation (Chen et al, 1985;Cerdan et al, 1991;Palacio et al, 1997a).…”

“…TNF-α can maintain keratinocytes in an activated state (Freedberg et al, 2001). After activation, keratinocytes also express surface molecules such as the intercellular adhesion molecule ICAM-1/CD54, a ligand of the leukocyte function-associated antigen LFA-1 (Caughman et al, 1990;Cerdan et al, 1991). In addition to their frequent autocrine effects, many substances released by the activated keratinocytes act in a paracrine manner on different cell types (T lymphocytes, granulocytes, dendritic cells, Langerhans cells, endothelial cells, fibroblasts and melanocytes) contributing to cellular activation, differentiation and chemotaxis and to induction of adhesion molecule expression (Chen et al, 1985;Caughman et al, 1990;Kock et al, 1990;Kimber and Cumberbatch, 1992;Gueniche et al, 1995).…”

“…Studies on human keratinocytes and on laboratory rodents have shown that many exogenous and endogenous factors can lead to cutaneous epidermal cell activation (Caughman et al, 1990;Cerdan et al, 1991). Skin exposure to ultraviolet radiation, viral infections, irritants and allergens can induce keratinocyte activation (Chen et al, 1985;Cerdan et al, 1991;Palacio et al, 1997a). In inflammatory cutaneous reactions, endogenous factors such as interferon gamma (IFN-γ) produced by activated T lymphocytes play a major role in the induction of cutaneous epithelial cell activation, via their corresponding specific receptors expressed on keratinocytes (Griffiths and Nickoloff, 1989;Luger and Schwarz, 1990;Stingl, 1993).…”