A NICOTINIC ACETYLCHOLINE-RECEPTOR REGULATING CELL-ADHESION AND MOTILITY IS EXPRESSED IN HUMAN KERATINOCYTES

Acetylcholine is synthesized and released by human epidermal keratinoc ytes and modulates the adhesion and motility of these cells. To unders tand the molecular basis of the effects of acetylcholine on keratinocy tes, we investigated the presence, pharmacology, structure, and functi on of nicotinic acetylcholine receptors in human epidermal keratinocyt es. Patch-clamp studies indicated that keratinocytes express acetylcho line receptors with ion gating and pharmacologic properties similar to those observed so far only in neurons, and containing the alpha(3) su bunit. Specific binding of the receptor-specific ligand I-125-kappa-bu ngarotoxin revealed approximately 5500 binding sites per cell on undif ferentiated keratinocytes in cell cultures and approximately 35,400 bi nding sites per cell on mature keratinocytes freshly isolated from hum an neonatal foreskins. Antibody binding and polymerase chain reaction experiments demonstrated the presence of alpha(3), beta(2), and beta(4 ) nicotinic receptor subunits. Binding of subunit-specific antibodies indicated that nicotinic receptors were associated with the suprabasal keratinocytes in epidermis and localized to the cell membranes of dif ferentiated keratinocytes in cell cultures. Acetylcholine and the nico tinic agonist nicotine increased cell-substrate and cell-cell adherenc e of cultured keratinocytes and stimulated their lateral migration. Th e specific antagonists K-bungarotoxin and mecamylamine caused cell det achment and abolished migration. Thus, a nicotinic receptor expressed in keratinocytes may mediate acetylcholine control of keratinocyte adh esion and motility.