| Co-Investigator(Kenkyū-buntansha) |
MATSUDA Kazuhiro Nat'l Cancer Ctr, Virol. Glyocobiol., Staff scientist, ウイルス部, 主任研究官 (80251502)
ISHII Atsushi Nat'l Cancer Ctr, Virol. Glyocobiol., Escheat, ウイルス部, 室長 (20232225)
HAMANAKA Yuichiro Nat'l Cancer Ctr, Virol. Glyocobiol., Staff scientist, ウイルス部, 主任研究官 (40189618)
SAKAI Ryuichi Nat'l Cancer Ctr, Virol. Glyocobiol., Sec. head, ウイルス部, 室長 (40215603)
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| Research Abstract |
Glycoconjugates from the frontier of cell-to-cell and cell-to-substratum interactions. Among them, gangliosides (sialic acid containing glycosphingolipids) are known to bear important functions in various biological phenomena such as cell growth and differentiation, embryogenesis and carcinogenesis. In vertebrates, almost all the gangliosides are synthesized from a common pre-cursor, ganglioside GM3, which was previously shown by us to exhibit differentiation-inducing activity against human myelogenous leukemia cells. In this project, using the ellaborately-devised expression cloning method, we succeeded for the first time in isolating and molecularly characterizing a new and relevant gene (cDNA and genome) which encodes a key glycosyltransferase, human ganglioside GM3 synthase (sialyltransferase-1: ST3GalV) and then, murine ST3GalV, which is responsible for GM3 biosynthesis. Subsequently, 3 kinds of transcripts (L-,B1-and B2-type) of the gene were detected in mice by 5'-RACE analyses
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whereas a single transcript detectable in human organs, and murine tissue-specific expressions were clarified: L-type transcript was specifically expressed in liver while B1-type was generally detected in various organs with B2-type marginally expressed. The human and murine genomic structures of ST3GalV have been determined by screening BAC and 【lambda bar】 library, respectively, prepared from the chromosomal DNA. Transfection of this enzyme cDNA into ganglioside-deficient mouse lung carcinoma 3LL cells was interestingly shown to introduce the characteristic shedding of GM3-rich membrane domain into the medium. In the programs for exploitation of natural and synthetic sialoglycocompounds, i.e. neoglycolipids, in the applications to the medical fields, the hydrophobic (fatty acid) moiety of ganglioside GM3 was changed in the chemically-synthesized molecule in order to enhance its biological activity, and, among more than 20 synthetic sialoglycolipid compounds, both α-sialo-cholesterol and α-sialodiglyceride were shown to exhibit significant differentiation-including and apoptosis-including activities to human leukemia cells. Anti-sense oligonucleotide therapy for human melanomas is initiated using GD3 synthase cDNA since GD3-dominant melanoma was reported worse in the prognosis. We could produce ST3GalV soluble forms as MBP-/GST-fusion proteins in order to utilize in the development of automatic carbohydrate-chain synthesizers. We have also devised newly the toroidal coil counter-current chromatography to isolate less polar alkali-labile glycolipids and proteins with higher sensitivity. Less
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