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

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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.