|Budget Amount *help
¥2,400,000 (Direct Cost : ¥2,400,000)
Fiscal Year 1997 : ¥800,000 (Direct Cost : ¥800,000)
Fiscal Year 1996 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1995 : ¥700,000 (Direct Cost : ¥700,000)
We have tried to isolate a cDNA clone encoding human sulfotransferase, which could synthesize sulfated LacCer. In this research, we used a mammalian expression system with monoclonal antibodies which were established against sulfated glycolipids in our laboratory, and found that de novo expression of transgected cells. However, we are still in the way to get a cDNA that represent a tructural gene encoding a human sulfotransferase.
At the same time, we have investigated expression pattern of the GalCer sulfotransferase which was recently cloned, among human liver and hepatoma cell lines. In Northern blots, the gene was expressed in human hepatoma cell lines in relation to product of sulfoglycolipids in these cells. This result might suggest that the enzyme encoded by the gene could synthesize sulfated LacCer, and this issue should be resolved upon analysis of enxymatic function derived from this gene.
Among acidic glycolipids and glycoproteins, sialylated glyco-structures have function of cell adhesion like sulfated glycolipids, and we have investigated that expression of glycosyltransferases related to these products were actually regulatted in cancer-related and cell-specific condition. Especially some transferase is under the influence of the transcription activator of the oncovirus in synthesis of sialyl Le^x which mediates adhesion of leukocytes and leukemic cells to endothelium.
2.末端ガラクトースに硫酸基の結合した構造の中で、最も単純な構造(SM3)の合成に関与する、糖脂質特異的硫酸基糖転移酵素が先日報告されたが、そのcDNAのcoding regionの断片を用いて、硫酸化糖脂質の存在が証明された(Hiraiwa,N.,et al.Cancer Res.50:2917-2928,1990)ヒト肝癌細胞株、胆肝癌および硫酸化糖脂質の合成を認められなかったヒト正常肝由来細胞の同酵素の転写発現をNorthern blotで調べたところ、同糖脂質合成量と遺伝子転写発現量とは正の相関を見た。現在、同酵素遺伝子を正常肝由来細胞に安定発現させ、硫酸化糖脂質の合成、細胞接着などの機能変化を研究している。