1999 Fiscal Year Final Research Report Summary
Molecular biological studies of HNK-1 carbohydrate epitope
| Project/Area Number |
09307053
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Biological pharmacy
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| Research Institution | KYOTO UNIVERSITY |
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Principal Investigator |
KAWASAKI Toshisuke Grad. Sch. Pharm. Sci., Kyoto U., Professor, 薬学研究科, 教授 (50025706)
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| Co-Investigator(Kenkyū-buntansha) |
OKA Shogo Grad. Sch. Pharm. Sci., Kyoto U., Associate Professor, 薬学研究科, 助教授 (60233300)
KOZUTSUMI Yasunori Grad. Sch. of Biostudies, Kyoto U., Professor, 生命科学研究科, 教授 (70205425)
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| Project Period (FY) |
1997 – 1999
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| Keywords | HNK-1 epitope / 3-sulfoglucuronic acid / glucuronyltransferase / cell adhesion molecule / COS-1 cells / sulfotransferase / Extra Cellular Matrix / C6 glioma |
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| Research Abstract |
The HNK-1 carbohydrate epitope is characteristically expressed on a series of cell adhesion molecules and also on some glycolipids in the nervous system over a wide range of species from insect to mammal. The HNK-1 epitope is involved in cell-cell and/or cell-substrate interaction and recognition during the development of the nervous system. The HNK-1 epitope has been demonstrated to be composed of the sulfated trisaccharides, sulfate-3GlcAβ1-3Galβ1-4GlcNAc, which is shared with glycolipids and glycoproteins We isolated a novel glucuronyltransferase (GlcAT-P) from rat brain which is a key enzyme of the biosynthesis of the HNK-1 epitope on glycoproteins. The primary structure deduced from the cDNA sequence predicted a type II transmembrane protein with 347 amino acids and had no detectable similarity with any other proteins of known functions, including glucuronyltransferases of the liver and olfactory epithelium. Expression of a soluble recombinant form of the enzyme in COS-1 cells produced an active glucuronyltransferase. Transfection of GlcAT-P cDNA into COS-1 cells induced not only expression of the HNK-1 epitope on the cell surface but also marked morphological changes of the cells, suggesting that the HNK-1 epitope associates with the cell-substratum interaction. In addition, cell aggregation analysis revealed that the parental C6 cells showed a strong tendenecy to aggregation in time-dependent manner,whereas C6/GlcAT-P cells showed a markedly reduced rate of cell aggregation. We also provided the evidence that NCAM-NCAM homophilic binding is negatively regulated by the presence of HNK-1 carbohydrate epitope. These lines of evidence suggested that the HNK-1 epitope expressed on cell adhesion molecules such as NCAM and L1 negatively regulated their homophilic interactions and resulted in reducing the cell-cell adhesion.
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