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Lack of effect of Miller Fisher sera/plasmas on transmitter release from PC12 cells
M G Benatar1, H J Willison, A Vincent
1Institute of Molecular Medicine, University of Oxford, UK.
Abstract:
IgG antibodies to GQ1b ganglioside are found in > 90% of patients with the Miller Fisher Syndrome (MFS). MFS sera or IgG preparations have marked effects on neurotransmitter release at the neuromuscular junction, but their mode(s) of action remain unclear. To establish a cell-based system for investigating the mechanism of action of MFS serum preparations, we looked at neurotransmitter release from three cell lines. We failed to demonstrate substantial 14C-acetylcholine release from two motor-neuronal cell lines, VSC4.1 and NSC19, and therefore studied 3H-noradrenaline release from NGF-differentiated PC12 cells, a neural-crest derived catecholaminergic cell line. K(+)-induced release was inhibited by botulinum toxin and basal release was enhanced by alpha-latrotoxin, resembling that at the neuromuscular junction, although K(+)-induced release was dependent on L-type rather than P/Q-type calcium channels. The cells expressed polysialylated gangliosides on the cell surface. Incubation in heat-inactivated or untreated MFS preparations did not, however, affect basal or K(+)-induced release. Thus the PC12 cells do not appear to be sensitive to the effects of serum antibodies from MFS patients.
Insights
Miller Fisher Syndrome (MFS) antibodies target GQ1b gangliosides. Researchers developed a cell-based system but found PC12 cells insensitive to MFS serum, hindering mechanism studies.
Area of Science:
- Neuroscience
- Immunology
- Cell Biology
Background:
- Miller Fisher Syndrome (MFS) is characterized by IgG antibodies against GQ1b gangliosides in over 90% of patients.
- MFS serum or IgG impacts neurotransmitter release at the neuromuscular junction, but the exact mechanisms are not fully understood.
Purpose of the Study:
- To establish a cell-based system for investigating the mechanism of action of MFS serum preparations on neurotransmitter release.
- To assess the utility of PC12 cells, a catecholaminergic cell line, in studying MFS antibody effects.
Main Methods:
- Evaluated neurotransmitter release (14C-acetylcholine and 3H-noradrenaline) from neuronal cell lines (VSC4.1, NSC19) and NGF-differentiated PC12 cells.
- Characterized neurotransmitter release in PC12 cells using K+ stimulation, botulinum toxin, alpha-latrotoxin, and calcium channel blockers.
- Assessed the impact of MFS serum preparations on basal and stimulated neurotransmitter release from PC12 cells.
Main Results:
- PC12 cells exhibited K(+)-induced release of 3H-noradrenaline, modulated by botulinum toxin and alpha-latrotoxin, with L-type calcium channel dependency.
- These cells expressed polysialylated gangliosides on their surface.
- Incubation with MFS serum preparations (heat-inactivated or untreated) did not alter basal or K(+)-induced neurotransmitter release from PC12 cells.
Conclusions:
- NGF-differentiated PC12 cells, despite expressing gangliosides, are not a suitable model for studying the direct effects of MFS serum antibodies on neurotransmitter release.
- Further research is needed to identify appropriate cell-based systems to elucidate the mechanisms underlying MFS pathogenesis.