BISECTING GLCNAC STRUCTURE IS IMPLICATED IN SUPPRESSION OF STROMA-DEPENDENT HEMATOPOIESIS IN TRANSGENIC MICE EXPRESSING N-ACETYLGLUCOSAMINYLTRANSFERASE-III

Several sugar structures have been reported to be necessary for haemop oiesis. We analysed the haematological phenotypes of transgenic mice e xpressing beta-1,4 N-acetylglucosaminyltransferase III (GnT-III), whic h forms bisecting N-acetylglucosamine on asparagine-linked oligosaccha rides. In the transgenic mice, the GnT-III activity was elevated in bo ne marrow, spleen and peripheral blood and in isolated mononuclear cel ls from these tissues, whereas no activity was found in these tissues of wild-type mice. Stromal cells after long-term cultures of transgeni c-derived bone marrow and spleen cells also showed elevated GnT-III ac tivity, compared with an undetectable activity in wild-type stromal ce lls. As judged by HPLC analysis, lectin blotting and lectin cytotoxici ty assay, bisecting GlcNAc residues were increased on both blood cells and stromal cells from bone marrow and spleen in transgenic mice. The transgenic mice displayed spleen atrophy, hypocellular bone marrow an d pancytopenia. Bone marrow cells and spleen cells from transgenic mic e produced fewer haemopoietic colonies. After lethal irradiation follo wed by bone marrow transplantation, transgenic recipient mice showed p ancytopenia compared with wild-type recipient mice. Bone marrow cells from transgenic donors gave haematological reconstitution at the same level as wild-type donor cells. In addition, non-adherent cell product ion was decreased in long-term bone marrow cell cultures of transgenic mice. Collectively these results indicate that the stroma-supported h aemopoiesis is compromised in transgenic mice expressing GnT-III, prov iding the first demonstration that the N-glycans have some significant roles in stroma-dependent haemopoiesis.