Sulfation of glucuronic acid in the linkage tetrasaccharide by HNK-1 sulfotransferase is an inhibitory signal for the expression of a chondroitin sulfate chain on thrombomodulin.
HNK-1 (human natural killer-1) carbohydrate epitope (HSO(3)-3GlcAβ1-3Galβ1-4GlcNAc-) recognized by a HNK-1 monoclonal antibody is highly expressed in the nervous system and biosynthesized by a glucuronyltransferase (GlcAT-P or GlcAT-S), and sulfotransferase (HNK-1ST). A similar oligosaccharide (HSO(3)-3GlcAβ1-3Galβ1-3Galβ1-4Xyl) also recognized by the HNK-1 antibody had been found in a glycosaminoglycan (GAG)-protein linkage region of α-thrombomodulin (TM) from human urine. However, which sulfotransferase is involved in sulfation of the terminal GlcA in the GAG-protein linkage region remains unclear. In this study, using CHO-K1 cells in which neither GlcAT-P nor GlcAT-S is endogenously expressed, we found that HNK-1ST has the ability to produce HNK-1 immunoreactivity on α-TM. We also demonstrated that HNK-1ST caused the suppression of chondroitin sulfate (CS) synthesis on TM and a reduction of its anti-coagulant activity. Moreover, using an in vitro enzyme assay system, the HNK-1-positive TM was found not to be utilized as a substrate for CS-polymerizing enzymes (chondroitin synthase (ChSy) and chondroitin polymerizing factor (ChPF)). These results suggest that HNK-1ST is involved in 3-O-sulfation of the terminal GlcA of the linkage tetrasaccharide which acts as an inhibitory signal for the initiation of CS biosynthesis on TM.
Department of Biological Chemistry, Human Health Sciences, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan.
Naoki
N
Nakagawa
Tomomi
T
Izumikawa
Hiroshi
H
Kitagawa
Shogo
S
Oka
D000818:Animals; D002240:Carbohydrate Sequence; D002460:Cell Line; D002809:Chondroitin Sulfates / Q000096:biosynthesis* / Q000737:chemistry; D006224:Cricetinae; D003412:Cricetulus; D020723:Glucuronic Acid / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism*; D013431:Sulfates; D015238:Sulfotransferases / Q000378:metabolism*; D018180:Thrombomodulin / Q000737:chemistry / Q000378:metabolism*
C569218:HSO(3)-3GlcAbeta1-3Galbeta1-3Galbeta1-4Xyl; D009844:Oligosaccharides; D013431:Sulfates; D018180:Thrombomodulin; D020723:Glucuronic Acid; D002809:Chondroitin Sulfates; C109318:HNK-1 sulfotransferase; D015238:Sulfotransferases