Significant decrease in alpha1,3-linked fucose in association with increase in 6-sulfated N-acetylglucosamine in peripheral lymph node addressin of FucT-VII-deficient mice exhibiting diminished lymphocyte homing.
Lymphocyte homing is mediated by binding of L-selectin on lymphocytes with L-selectin ligands present on high-endothelial venules (HEV) of peripheral and mesenteric lymph nodes. L-selectin ligands are specific O-linked carbohydrates, 6-sulfo sialyl Lewis X, composed of sialylated, fucosylated, and sulfated glycans. Abrogation of fucosyltransferase-VII (FucT-VII) results in almost complete loss of lymphocyte homing, but structural analysis of carbohydrates has not been carried out on FucT-VII null mice. To determine whether functional losses seen in FucT-VII null mice are caused by structural changes in carbohydrates, we elucidated the carbohydrate structure of GlyCAM-1, a major L-selectin counter-receptor. Our results show that most alpha1,3-fucosylated structures in 6-sulfo sialyl Lewis X are absent and 6-sulfo N-acetyllactosamine is increased in the mutant mice. Surprisingly, the amount of 6'-sulfated galactose (Gal) that bound to Sumbucus nigra agglutinin column was also increased. We found that structures of those oligosaccharides containing 6'-sulfated Gal are almost identical to those synthesized by keratan sulfate sulfotransferase (KSST). We then showed that overexpression of KSST suppresses the expression of sialyl Lewis X on Chinese hamster ovary (CHO) cells engineered to express sialyl Lewis X. Moreover, KSST expression in those cells suppressed lymphocyte rolling compared with mock-transfected CHO cells expressing 6-sulfo sialyl Lewis X. 6'-Sulfo sialyl Lewis X can neither be found in GlyCAM-1 from CHO cells expressing both KSST and FucT-VII nor be found in GlyCAM-1 from HEV of mice. These results combined together suggest that KSST competes with FucT-VII for the same acceptor substrate and downregulates the synthesis of L-selectin ligand by inhibiting alpha1,3-fucosylation.
Hiraoka
Nobuyoshi
N
Glycobiology Program, Cancer Research Center, Burnham Institute for Medical Research, La Jolla, CA 92037, USA.
Petryniak
Bronislawa
B
Kawashima
Hiroto
H
Mitoma
Junya
J
Akama
Tomoya O
TO
Fukuda
Michiko N
MN
Lowe
John B
JB
Fukuda
Minoru
M
D000117:Acetylglucosamine / Q000031:analogs & derivatives* / Q000032:analysis / Q000378:metabolism; D000818:Animals; D000954:Antigens, Surface / Q000737:chemistry* / Q000378:metabolism; D016466:CHO Cells; D002240:Carbohydrate Sequence; D002465:Cell Movement; D006224:Cricetinae; D003412:Cricetulus; D005643:Fucose / Q000032:analysis* / Q000378:metabolism; D005647:Fucosyltransferases / Q000172:deficiency* / Q000235:genetics; D016256:Lewis X Antigen / Q000031:analogs & derivatives; D008214:Lymphocytes / Q000201:enzymology / Q000276:immunology*; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D009077:Mucins / Q000737:chemistry* / Q000378:metabolism; D009844:Oligosaccharides / Q000032:analysis / Q000378:metabolism; D011134:Polysaccharides / Q000032:analysis; D000080506:Sialyl Lewis X Antigen / Q000031:analogs & derivatives; D015238:Sulfotransferases / Q000235:genetics / Q000378:metabolism; D000097811:Carbohydrate Sulfotransferases
D000117:Acetylglucosamine; D000954:Antigens, Surface; D005643:Fucose; D005647:Fucosyltransferases; D016256:Lewis X Antigen; D008565:Membrane Proteins; D009077:Mucins; D009844:Oligosaccharides; D011134:Polysaccharides; D000080506:Sialyl Lewis X Antigen; D015238:Sulfotransferases; D000097811:Carbohydrate Sulfotransferases; C086949:6'-sulfated sialyl Lewis x; C069886:L-selectin counter-receptors; C033137:N-acetylglucosamine-6-sulfate; C075185:sulfated glycoprotein p50; C514210:fucosyltransferase VII, mouse