Biosynthesis of sulfated L-selectin ligands in human high endothelial venules (HEV).
High endothelial venules (HEVs) are specialized post-capillary venules found in lymphoid tissues, that support high levels of lymphocyte extravasation from the blood. Lymphocyte L-selectin plays a key role in the initial interaction of lymphocytes with HEVs by recognizing sulfated carbohydrate ligands on HEV mucin-like glycoproteins, GlyCAM-1, CD34 and MAdCAM-1. Sulfation is key to the uniqueness of the HEV ligands since 6 or 6'-sulfated-sLe(x) isoforms have recently been identified as major capping groups of GlyCAM-1 and sulfation of both GlyCAM1 and CD34 has been shown to be required for high-affinity L-selectin binding and recognition by the HEV-specific monoclonal antibody MECA-79. To characterize the molecular mechanisms involved in the biosynthesis of sulfated L-selectin ligands in HEVs, we have started to isolate genes that play a role in sulfate metabolism in HEVs. Studies with chlorate, a selective inhibitor of the synthesis of the high energy donor of sulfate, PAPS (3'-phosphoadénosine 5'-phosphosulfate), had previously revealed that PAPS synthesis is required for sulfation of HEV ligands and recognition by L-selectin. Therefore, we screened an HEV cDNA library in order to isolate cDNAs encoding enzymes involved in PAPS synthesis. This strategy allowed us to isolate a novel cDNA encoding the PAPS synthetase from human HEVs. The molecular characteristics of PAPS synthetase and its role in biosynthesis of sulfated L-selectin ligands in HEVs are discussed.
Girard
J P
JP
Laboratoire de Biologie Moléculaire Eucaryote du CNRS, Toulouse, France.
Amalric
F
F
D000818:Animals; D002240:Carbohydrate Sequence; D004729:Endothelium, Lymphatic / Q000378:metabolism*; D006801:Humans; D019041:L-Selectin / Q000378:metabolism*; D008024:Ligands; D008214:Lymphocytes / Q000502:physiology; D008969:Molecular Sequence Data; D009077:Mucins / Q000096:biosynthesis* / Q000378:metabolism; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D013430:Sulfate Adenylyltransferase / Q000235:genetics / Q000378:metabolism; D013431:Sulfates / Q000378:metabolism
D008024:Ligands; D009077:Mucins; D009097:Multienzyme Complexes; D013431:Sulfates; D019041:L-Selectin; C022322:PAPS synthetase; D013430:Sulfate Adenylyltransferase