DIFFERENTIAL EXPRESSION OF AN E-SELECTIN LIGAND [SLE(X)] BY 2 CHINESE-HAMSTER OVARY CELL-LINES TRANSFECTED WITH THE SAME ALPHA(1,3)-FUCOSYL-TRANSFERASE GENE (ELFT)

The mammalian cDNA encoding alpha(1,3)-fucosyltransferase (alpha(1,3)F uc-T) termed ELAM-1 ligand fucosyltransferase (ELFT) or Fuc-TIV was pr eviously cloned by three groups who reported different results from tr ansfection studies Goelz et al. (Goelz, S. E., Hession, C., Goff, D., Griffiths, B., Tizard, R., Newman, B., Chi-Rosso, G., and Lobb, R. (19 90) Cell 63, 1349-1356) found that Chinese hamster ovary (CHO) cells e xpressing the ELFT cDNA had alpha(1,3)Fuc-T activity and were able to bind to E-selectin. In contrast, Lowe et al. (Lowe, J. B., Kukowska-La tallo, J. F., Nair, R. P., Larsen, R. D., Marks, R. M., Macher, B. A., Kelly, R. J., and Ernst, L. K. (1991) J. Biol. Chem. 266, 17467-17477 ) and Kumar et al. (Kumar, R., Potvin, B., Muller, W. A., and Stanley, P. (1991) J. Biol. Chem. 266, 21777-21783) found no binding to E-sele ctin of CHO transfectants expressing the same alpha(1,3)Fuc-T gene; no r did the latter transfectants synthesize a known E-selectin ligand, s ialylated Le(x) (SLe(x)), although they had substantial alpha(1,3)Fuc- T activity. We now show that these discrepant results were due to a di fference between the parental CHO cell lines. Following transfection o f ELFT cDNA into Pro-5 or dihydrofolate reductase (DHFR)- CHO cells, o nly the DHFR- transfectants expressed SLe(x) and bound to E-selectin. Indirect evidence from monoclonal antibody and lectin binding studies indicates that the range of carbohydrate structures synthesized by the Pro-5 and DHFR- CHO cell lines differs. Since DHFR-/ELFT transfectant s expressed cell surface SLe(x) but transferred fucose poorly to sialy lated substrates in vitro, ELFT may be able to fucosylate a complex ca rbohydrate missing from Pro-5 cells. Alternatively, either CHO line ma y have an activity (such as an alpha(2,3)-sialyltransferase), that mod ifies alpha(1,3)-fucosylated lactosamines.