Characterization of human vascular endothelial cadherin glycans

The glycosylation pattern of human vascular endothelial cadherin (VE-cadher in), purified from cultured human umbilical cord vein endothelial cells, wa s analyzed. VE-cadherin was metabolically radiolabeled with D-[6-H-3]glucos amine, isolated by immunoprecipitation, purified by SDS-PAGE and in-gel dig ested with endoproteinase Asp N, Oligosaccharides were sequentially release d from resulting glycopeptides and analyzed by chromatographic profiling. T he results revealed that VE-cadherin carries predominantly sialylated diant ennary and hybrid-type glycans in addition to some triantennary and high ma nnose-type species. Highly branched, tetra-antennary oligosaccharides were found in trace amounts only. Immunohistochemical labeling of VE-cadherin an d sialic acids displayed a codistribution along the intercellular junctions in endothelial cells of human umbilical arteries, veins, and cultured endo thelial monolayers, Ca2+-depletion, performed on cultured endothelial cells , resulted in a reversible complete disappearance of VE-cadherin and of alm ost all sialic acid staining from the junctions. Sialidase treatment of who le cells caused a change of VE-cadherin immunofluorescence from a continuou s and netlike superstructural organization to a scattered inconsistent one. Hence, cell surface sialic acids might play a role in VE-cadherin organiza tion.