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 (LeX) and Lewis Y (LeY) antigens are key determinants for a variety of biological processes. We studied the changes in LeX and LeY expression in Jurkat cells, a human T cell line, during apoptosis. Flow cytometry showed that LeX and LeY antigen expression was enhanced on the cell surface during apoptosis induced by anti-Fas antibody. To clarify the mechanism of enhanced LeX 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 LeX and LeY. The expression of FUT4 mRNA was up-regulated after exposing cells to anti-Fas antibody. Moreover, the increase in LeX and LeY 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 LeX and LeY expression in apoptotic cells.
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