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An activation-associated ganglioside in rat thymocytes
K Nohara1, T Sano, F Shiraishi
1Environmental Health Sciences Division, National Institute for Environmental Studies, Ibaraki, Japan.
The Journal of Biological Chemistry
|November 25, 1993
Summary
Rat thymocyte activation significantly increases total gangliosides, with GD1c and a novel GD1b variant rising. Concanavalin A stimulation yields a more pronounced ganglioside increase than TPA/A23187.
Area of Science:
- Biochemistry
- Immunology
- Cell Biology
Background:
- Gangliosides are crucial glycosphingolipids involved in cell recognition and signaling.
- Thymocyte activation is a complex process involving changes in cell surface molecules.
Purpose of the Study:
- To investigate the alterations in ganglioside composition during rat thymocyte activation.
- To identify and characterize novel gangliosides that emerge upon thymocyte stimulation.
Main Methods:
- Rat thymocytes were activated using 12-O-tetradecanoylphorbol-13-acetate (TPA) with calcium ionophore A23187, or concanavalin A (ConA).
- Ganglioside levels were quantified at 24-h intervals post-activation.
- Structural elucidation of novel gangliosides involved compositional analysis, methylation analysis, sialidase hydrolysis, and proton NMR spectroscopy.
Main Results:
- TPA/A23187 stimulation led to a several-fold increase in total gangliosides, with elevated GD1c and a newly identified GD1b variant containing two N-glycolylneuraminic acid residues.
- ConA stimulation resulted in a more substantial increase in total gangliosides compared to TPA/A23187.
- ConA-activated thymocytes showed increased levels of multiple gangliosides beyond GD1c and the novel GD1b.
Conclusions:
- Thymocyte activation profoundly alters ganglioside profiles, with distinct patterns observed depending on the stimulant.
- The emergence of specific gangliosides like GD1b-(NeuGc,NeuGc) is associated with thymocyte activation and proliferation.
- Differential ganglioside expression may play a role in the distinct functional outcomes of thymocyte activation by different mitogens.