Mechanism and therapeutic application of the gangliosides specifically expressed in ATL and HTLV-I infected cells.

为了探讨GD2神经节苷脂在ATL和HTLV-I感染细胞中特异性表达的调控机制，采用真核细胞表达克隆的方法克隆了β-1，4-氨基半乳糖转移酶(GM2/GD2合酶)基因的全长。该酶是由533个氨基酸组成的II型膜蛋白，结合在高尔基体膜上，跨膜区位于N端附近。以该基因为探针，经Northern印迹和RT-PCR2检测，在ATL和HTLV-I阳性细胞中均有较高水平的β-1，4-GalNAc转移酶基因表达。2.用RT-PCR检测ATL患者白血病细胞中β-1，4-GalNAc转移基因和HTLV-I基因的表达。3.正常外周T淋巴细胞在逆转录病毒载体中表达高水平的GD2，也表达高水平的β-1，4-GalNAc转移酶基因，这些结果提示p40-1，4-GalNAc转移酶基因的激活导致HTLV-I阳性细胞中GD3向GD2的转化。为了研究这些调控的分子机制，我们分离了β-1，4-GalNAc转移酶基因，并对其外显子-内含子结构进行了分析。目前正在分析5‘侧翼区启动子/增强子的活性和特异性。

In order to investigate the regulatory mechanisms for the specific expression of GD2 ganglioside in ATL and HTLV-I infected cells, cDNA of beta1,4 GalNAc transferase(GM2/GD2 syn thase)gene was isolated by using eukaryotic cell expression cloning. This enzyme turned out to be type II membrane protein with 533 amino acids, anchoring on the Golgi membrane with transmembrane domain which is located near the N-terminus. Using this gene as a probe, following findings have been obtained.1.High levels of expression of beta1,4 GalNAc transferase gene were demonstrated in ATL or HTLV-I positive cells by Northern blot and RT-PCR.2.Expression of beta1,4 GalNAc transferse gene and HTLV-I p40^<tax> gene was examined by using leukemia cells from ATL patients with RT-PCR.In four out of 6 samples, definite expression of pX mRNA was detected. beta1,4 GalNac transferase mRNA was also detected in the same 4 samples.3.Normal peripheral T lymphocytes expressing p40^<tax> with retroviral vector expressed high level of GD2, and also expressed high level of beta1,4 GalNac transferase gene in comparison with control sanples.These results suggested that beta1,4 GalNAc transferase gene was being activated by transaction of p40^<tax>, resulting in the conversion of GD3 to GD2 in HTLV-I positive cells. In order to examine the molecular mechanisms for these regulations, beta1,4 GalNAc transferase gene was isolated and the exon-intron structne was analyzed. Activity and specificity of promoter/enhancer at 5' flanking region arenow being analyzed.