Sulfation and sialylation requirements for a glycoform of CD34, a major endothelial ligand for L-selectin in porcine peripheral lymph nodes.
Leukocyte recruitment from blood into peripheral lymph nodes is controlled in part by a specific interaction of lymphocyte-associated L-selectin with endothelial cell receptors known as peripheral addressins. In murine lymph nodes, two peripheral addressins have been identified, Gly-CAM-1, a 50 kDa molecule that also appears as a secreted form in plasma, and CD34, a 90 kDa membrane-associated sialomucin. A predominant 105 kDa CD34 mucin-like protein has also been identified in human tonsil as peripheral addressin. We have identified a 120 kDa sialomucin as the predominant peripheral addressin in porcine lymph nodes. Validation of the 120 kDa porcine molecule as a peripheral addressins was based on its ability to bind MECA-79, a monoclonal antibody previously used to isolate peripheral addressins from mouse and human tissues, and to bind an L-selectin-Fc chimera (LS-Fc). The binding with LS-Fc was abolished in the presence of fucoidin, a sulfated polysaccharide known to inhibit L-selectin-receptor interactions. To address the possibility that the 120 kDa ligand may contain common recognition determinants for MECA-79 and L-selectin, the requirements for sialylation and sulfation were compared. Whereas desialylation of 120 kDa ligand drastically reduced its binding to LS-Fc, this treatment appeared to enhance the binding of 120 kDa ligand to MECA-79. In contrast, the binding of both MECA-79 and LS-Fc to 120 kDa ligand was drastically reduced when de novo sulfation of this ligand was reduced by including chlorate, a metabolic inhibitor of sulfation, in the culture media. N-Terminal amino acid sequences of the porcine 120 kDa protein revealed homology with human CD34. Taken together, these findings suggest that the porcine 120 kDa peripheral addressin is an L-selectin-binding glycoform of CD34.
Shailubhai
K
K
Department of Immunology, G. D. Searle Co., a subsidiary of Monsanto Co., St. Louis, MO 63167, USA.
Streeter
P R
PR
Smith
C E
CE
Jacob
G S
GS
D000595:Amino Acid Sequence; D000818:Animals; D018952:Antigens, CD34 / Q000378:metabolism*; D000954:Antigens, Surface / Q000378:metabolism*; D004727:Endothelium / Q000378:metabolism*; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000235:genetics / Q000378:metabolism; D019041:L-Selectin / Q000235:genetics / Q000378:metabolism*; D008024:Ligands; D008198:Lymph Nodes / Q000378:metabolism*; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D019158:N-Acetylneuraminic Acid / Q000378:metabolism; D011485:Protein Binding; D016201:Receptors, Lymphocyte Homing / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017421:Sequence Analysis; D017386:Sequence Homology, Amino Acid; D013431:Sulfates / Q000378:metabolism; D013552:Swine
D018952:Antigens, CD34; D000954:Antigens, Surface; D007141:Immunoglobulin Fc Fragments; C069886:L-selectin counter-receptors; D008024:Ligands; D008565:Membrane Proteins; D016201:Receptors, Lymphocyte Homing; D011993:Recombinant Fusion Proteins; D013431:Sulfates; D019041:L-Selectin; D019158:N-Acetylneuraminic Acid