O-glycans on human high endothelial CD34 putatively participating in L-selectin recognition.
Leukocyte traffic into lymph nodes and sites of inflammation is guided by L-selectin. Experiments performed in vitro and with gene-deleted mice suggest that CD34 recognizes L-selectin if decorated by 6-sulfo sialyl Lewis x (sLex) saccharides and the MECA-79 epitope. However, very little is known about glycosylation of human L-selectin ligands. We report here on matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiles of N- and O-linked oligosaccharide fractions from human tonsillar endothelial CD34. All detected O-glycans were sialylated; some were also monosulfated or monosulfated and monofucosylated. If a given CD34-glycan may carry all requirements for L-selectin recognition, that is, both 6-sulfo-sLex and MECA-79 epitopes, only one O-glycan fraction, O-9, SA(2)Hex(3)HexNAc(3)- Fuc(1)(SO(3))(1), meets the criteria. A candidate structure is SAalpha2-3Galbeta1-4(Fucalpha1-3)(6-sulfo)GlcNAcbeta1-3Galbeta1-3(SAalpha2-3Galbeta1-4GlcNAcbeta1-6)GalNAc. However, if sulfo sLex glycans are supplemented with separate sulfated, nonfucosylated O-glycans, saccharides in O-6, O-8, or O-9, putatively carrying MECA-79 epitopes, could form multiglycan binding epitopes for L-selectin.
Satomaa
Tero
T
Institute of Biotechnology and Department of Biosciences, Biomedicum and Haartman Institute, Haartmaninkatu 8, SF-00014 University of Helsinki, Helsinki, Finland.
Renkonen
Ossi
O
Helin
Jari
J
Kirveskari
Juha
J
Mäkitie
Antti
A
Renkonen
Risto
R
D000818:Animals; D015703:Antigens, CD / Q000502:physiology; D018952:Antigens, CD34 / Q000737:chemistry / Q000502:physiology*; D002240:Carbohydrate Sequence; D004727:Endothelium / Q000737:chemistry; D006031:Glycosylation; D006801:Humans; D006965:Hyperplasia; D019041:L-Selectin / Q000502:physiology*; D051379:Mice; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry*; D014066:Palatine Tonsil / Q000473:pathology; D011134:Polysaccharides / Q000032:analysis* / Q000737:chemistry; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014068:Tonsillectomy
D015703:Antigens, CD; D018952:Antigens, CD34; D009844:Oligosaccharides; D011134:Polysaccharides; D019041:L-Selectin