Highly fucosylated N-glycan ligands for mannan-binding protein expressed specifically on CD26 (DPPVI) isolated from a human colorectal carcinoma cell line, SW1116.
The serum mannan-binding protein (MBP) is a host defense C-type lectin specific for mannose, N-acetylglucosamine, and fucose residues, and exhibits growth inhibitory activity toward human colorectal carcinoma cells. The MBP-ligand oligosaccharides (MLO) isolated from a human colorectal carcinoma cell line, SW1116, are large, multiantennary N-glycans with highly fucosylated polylactosamine-type structures having Le(b)-Le(a) or tandem repeats of the Le(a) structure at their nonreducing ends. In this study, we isolated the major MBP-ligand glycoproteins from SW1116 cell lysates with an MBP column and identified them as CD26/dipeptidyl peptidase IV (DPPIV) (110 kDa) and CD98 heavy chain (CD98hc)/4F2hc (82 kDa). Glycosidase digestion revealed that CD26 contained such complex-type N-glycans that appear to mediate the MBP binding. MALDI-MS of the N-glycans released from CD26 by PNGase F demonstrated conclusively that CD26 is the major MLO-carrying protein. More interestingly, a comparison of the N-glycans released from the MBP-binding and non-MBP-binding glycopeptides suggested that complex-type N-glycans carrying a minimum of 4 Le(a)/Le(b) epitopes arranged either as multimeric tandem repeats or terminal epitopes on multiantennary structures are critically important for the high affinity binding to MBP. Analysis of the N-glycan attachment sites demonstrated that the high affinity MLO was expressed preferentially at some N-glycosylation sites, but this site preference was not so stringent. Finally, hypothetical 3D models of tandem repeats of the Le(a) epitope and the MBP-Lewis oligosaccharide complex were presented.
Kawasaki
Nobuko
N
Research Center for Glycobiotechnology, Ritsumeikan University, Shiga 525-8577, Japan.
Lin
Chia-Wei
CW
Inoue
Risa
R
Khoo
Kay-Hooi
KH
Kawasaki
Nana
N
Ma
Bruce Yong
BY
Oka
Shogo
S
Ishiguro
Masaji
M
Sawada
Toshihiko
T
Ishida
Hideharu
H
Hashimoto
Tomohiro
T
Kawasaki
Toshisuke
T
D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000737:chemistry* / Q000378:metabolism; D018819:Dipeptidyl Peptidase 4; D000939:Epitopes / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D005643:Fucose; D027282:Fusion Regulatory Protein 1, Heavy Chain; D006031:Glycosylation; D006801:Humans; D008024:Ligands; D037601:Mannose-Binding Lectin / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D009363:Neoplasm Proteins; D009844:Oligosaccharides / Q000096:biosynthesis / Q000737:chemistry* / Q000302:isolation & purification; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase / Q000737:chemistry; D013329:Structure-Activity Relationship
D000939:Epitopes; D027282:Fusion Regulatory Protein 1, Heavy Chain; D008024:Ligands; C445619:MBL2 protein, human; D037601:Mannose-Binding Lectin; D009363:Neoplasm Proteins; D009844:Oligosaccharides; D005643:Fucose; C042807:DPP4 protein, human; D018819:Dipeptidyl Peptidase 4; D043524:Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase