Expression of cell surface Lewis X and Y antigens and FUT4 mRNA is increased in Jurkat cells undergoing apoptosis.

Cell surface molecules undergo specific changes during apoptosis, including the expression of phosphatidylserine (PS) and some proteins and alterations in sugar chains. Among the various sugar chains on the cell surface, Lewis X (Le(X)) and Lewis Y (Le(Y)) antigens are key determinants for a variety of biological processes. We studied the changes in Le(X) and Le(Y) expression in Jurkat cells, a human T cell line, during apoptosis. Flow cytometry showed that Le(X) and Le(Y) antigen expression was enhanced on the cell surface during apoptosis induced by anti-Fas antibody. To clarify the mechanism of enhanced Le(X) and Le(Y) expression, we assessed the expression levels of fucosyltransferase (FUT1, 2, 3-5-6, 4, and 9) mRNAs that are predominantly expressed in Jurkat cells and which are considered to form Le(X) and Le(Y). The expression of FUT4 mRNA was up-regulated after exposing cells to anti-Fas antibody. Moreover, the increase in Le(X) and Le(Y) antigen levels was significantly suppressed by caspase 3 or 8 inhibitors. These results indicated that the induction of FUT (mainly FUT4), the gene expression of which is mediated by signals downstream of caspase 3, increases Le(X) and Le(Y) expression in apoptotic cells.