Expression of pemphigus vulgaris antigen in cultured human keratinocytes: Effect of inhibitors, tunicamycin, and lectins

We have investigated expression of pemphigus vulgaris antigen(s) in cultured human keratinocytes induced by the addition of extracellular calcium. Cycloheximide (10^-4 M) inhibited pemphigus antigen expression and stratification but actinomycin D (2μg/ml) had no effect. Tunicamycin, which inhibits dolichol pyrophosphate-mediated glycosylation of asparaginyl residues specifically, was used to study the role of glycosylation. When calcium switching was carried out in the presence of tunicamycin, human keratinocytes did not stratify, and the expression of pemphigus antigen was partially inhibited and limited to cell-cell contact areas. Analysis of biosynthetically labeled proteins showed that the synthesis of high-molecular-weight proteins was markedly reduced in the tunicamycin-treated cells. A reciprocal blocking test demonstrated that concanavalin A and wheat germ agglutinin receptor share an epitope with pemphigus vulgaris antigen(s). These results suggest that Ca⁺⁺, newly synthesized protein, and N-asparaginyl glycosylation are required for normal pemphigus antigen expression and epidermal stratification in vitro. Pemphigus vulgaris antigen may have a highly glycosylated, high-molecular-weight protein chain with carbohydrates playing an important role in epidermal cell morphology, adhesion, and stability of cell surface antigens.