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Updated: Jul 31, 2026
Antibody Binding Specificity for Kappa (Vκ) Light Chain-containing Human (IgM) Antibodies: Polysialic Acid (PSA) Attached to NCAM as a Case Study
Published on: June 29, 2016
A monoclonal antibody that induces neuronal apoptosis binds a metastasis marker
L T Zhong1, A Manzi, E Skowronski
1Interdepartmental Program in Neuroscience, University of California, Los Angeles, CA 90024, USA.
Abstract:
The cell surface molecules controlling apoptosis in cortical neurons are largely unknown. A monoclonal antibody was derived that induces cultured neocortical neurons to undergo apoptosis. A Fab fragment of the antibody, however, lacked the ability to induce cell death. The antigen was purified, and characterized by compositional analysis, fast atom bombardment (FAB) mass spectrometry, sequential exoglycosidase treatments, methylation analysis, and (1)H-nuclear magnetic resonance spectroscopy, proving to be isoglobotetraosylceramide (IsoGb4). IsoGb4 has been shown previously to be a metastasis marker, antibodies against which block metastases in a mammary adenocarcinoma model (S. A. Carlsen et al., Cancer Res., 53: 2906-2911, 1993). Addition of the purified antigen to cells lacking this glycolipid demonstrated that it is capable of functioning as a portable apoptosis-transducing molecule. Intracellular ceramide levels were increased after the treatment with the apoptosis-inducing antibody, but the membrane sphingomyelin level remained unchanged. Fumonisin B1 inhibited both the ceramide increase and the apoptosis induced via IsoGb4, which indicated that the ceramide synthase pathway is likely to be involved in apoptosis induction by IsoGb4.
Insights
Researchers identified isoglobotetraosylceramide (IsoGb4) as a key molecule inducing apoptosis in cortical neurons. This finding reveals a novel mechanism for programmed cell death, potentially impacting neurodegenerative disease research.
Area of Science:
- Neuroscience
- Cell Biology
- Immunology
Background:
- The precise cell surface molecules regulating apoptosis in cortical neurons remain largely unidentified.
- Understanding these regulators is crucial for deciphering neuronal cell death pathways.
Purpose of the Study:
- To identify and characterize the cell surface molecule responsible for inducing apoptosis in cultured neocortical neurons.
- To elucidate the mechanism by which this molecule transduces apoptotic signals.
Main Methods:
- Generation of a monoclonal antibody that induces neuronal apoptosis.
- Purification and structural characterization of the target antigen using mass spectrometry and NMR spectroscopy.
- Functional assays involving purified antigen and Fumonisin B1 treatment.
Main Results:
- The apoptosis-inducing antigen was identified as isoglobotetraosylceramide (IsoGb4).
- IsoGb4 functions as a portable molecule that can transduce apoptotic signals.
- IsoGb4-induced apoptosis involves an increase in intracellular ceramide levels, mediated by the ceramide synthase pathway.
Conclusions:
- Isoglobotetraosylceramide (IsoGb4) is a novel inducer of apoptosis in cortical neurons.
- The findings suggest a new pathway for programmed cell death involving IsoGb4 and ceramide metabolism.
- IsoGb4's role in apoptosis may have implications for understanding and treating neurological disorders.
