P-SELECTIN GLYCOPROTEIN LIGAND-1 IS ESSENTIAL FOR ADHESION TO P-SELECTIN BUT NOT E-SELECTIN IN STABLY TRANSFECTED HEMATOPOIETIC-CELL LINES

P-selectin (CD62P) is a member of the selectin family of adhesion mole cules involved in the regulation of leukocyte traffic. P-selectin glyc oprotein ligand-1 (PSGL-1) is a mucin-like molecule that is thought to be a primary ligand for P-selectin. The interaction of P-selectin wit h PSGL-1 results in leukocyte rolling and recruitment of leukocytes to sites of inflammation and tissue injury. However, expression of PSGL- 1 protein alone is insufficient for binding to P-selectin. Several pos ttranslational modifications of PSGL-1, including sialylation, sulfati on, and fucosylation by alpha 1,3-fucosyltransferase(s) (FucT), are re quired for functional interaction with P-selectin. Recently, several g roups have reported that PSGL-1 might also serve as a ligand for E-sel ectin. Differential posttranslational modifications of PSGL-1 may dete rmine whether it can interact with either P- or E-selectin or both. To determine whether PSGL-1 is essential for adhesion to P- or E-selecti n, we have constructed and analyzed a panel of stably transfected K562 cells. K562 cells express FucT-IV but not FucT-VII or PSGL-1, and do not bind to either E- or P-selectin. K562 cells transfected with PSGL- 1 cDNA also did not bind to either P- or E-selectin. Binding to P-sele ctin occurred only when K562 cells were cotransfected with both FucT-V II and PSGL-1. In contrast, expression of FucT-VlI alone was sufficien t for E-selectin binding. These data demonstrate that expression of PS GL-1 is not required for adhesion of a stably transfected hematopoieti c cell line to E-selectin, and suggest that FucT-IV alone cannot prope rty modify PSGL-1, expressed in transfected K562 cells, to bind P-sele ctin. (C) 1997 by The American Society of Hematology.