Structure and Function of a Ganglioside found Exclusively on the Surface of Neuroblastoma cells

2000 Fiscal Year Final Research Report Summary

• Project/Area Number: 11680602
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Structural biochemistry
• Research Institution: TOKYO INSTITUTE OF TECHNOLOGY
• Principal Investigator: SAITO Yuji Tokyo Institute of Technology, Graduate School of Bioscience and Biotechnology, Associate Professor, 大学院・生命理工学研究科, 助教授 (30134810)
• Project Period (FY): 1999 – 2000
• Keywords: Neuroblastoma cell / Monoclonal antibodies / Differentiation / Schewann cell / Neural cell / Lipid raft / CD44

Research Abstract

We immunized mice with intact cells of neuroblastoma GOTO cells and melanoma G361 cells and obtained two interesting monoclonal antibodies(mAbs), mAb I-13 and mAb AG23, which respectively recognized cell surface antigens. I tried to identify the antigens for two mAbs, and I investigated the differentiation of GOTO cells using these mAbs.
By fluorescence-activated cell sorter(FACS)analysis of various cells, the mAb I-13 recognized neuroblastoma cells GOTO and IMR-32 very well, but did not recognize other cells tested. On the other hand, the mAb AG23 recognized all cells tested except GOTO.It turned out that the antigen for mAb I-13 was a sphingolipid and that for AG23 was a glycoprotein, CD44.
5-Bromo-2' -deoxyuridine(BrdU)-treated GOTo cells, which are differentiated int Schwann cells, expressed CD44 on the cell surface. The CD44 species expressed was the hemopoietic form(CD44H)encoding long cytoplasmic tail. GOTO cells differentiated into neural cells by serum depletion did not express CD44. On the other hand, GOTO cells became a little less responsive with the mAb I-13 after the differentiation into Schwann as well as neural cells.
The antigen lipid was found exclusively in membrane microdomain, called lipid rafts. CD44 in BrdU-treated GOTO cells also partitioned itself into lipid rafts, although it was found in both plasma membrane fractions and lipid rafts fractions in the case of melanoma G361 cells. I think that CD44 in BrdU-treated GOTO cells might play an important role in cells differentiated into Schwann cells.