Xl. Chen et al., Overexpression of rat neuronal calcium sensor-1 in rodent NG1108-15 cells enhances synapse formation and transmission, J PHYSL LON, 532(3), 2001, pp. 649-659
1. The role of rat neuronal calcium sensor-1 (NCS-1), a Ca2+-bincling prote
in, in synapse formation and transmitter release was examined in mouse neur
oblastoma x rat glioma hybrid NG108-15 cells in culture.
2. Wild-type NG108-15 cells expressed rodent NCS-1. Endogenous NCS-1 was pa
rtially co-localized with the synaptic protein SNAP-25 at the plasma membra
ne in both cell bodies and processes, but not with the Golgi marker beta -C
OP, an individual coat subunit of the coatomer complex present on Golgi-der
ived vesicles.
3. In NG108-15 cells co-cultured with rat myotubes, partial co-localization
of SNAP-25 and NCS-1 was observed at the plasma membrane of neurites and g
rowth cones, some of which had synaptic contacts to muscle cells.
4. Transient co-transfection of the rat NCS-1 cDNA and green fluorescent pr
otein (GFP) resulted in NCS-1 overexpression in about 30% of the cells as d
etermined by fluorescence microscopy.
5. The rate of functional synapse formation with co-cultured rat myotubes i
ncreased 2-fold as determined by the presence of miniature endplate potenti
als (MEPPs) in NCS-1-overexpressing NG108-15 cells compared to non- and moc
k-transfected cells.
6. The number of neurites per cell, branches per neurite and length of neur
ites was slightly less in cells that; were either transiently transfected (
GFP-NCS-1-fluorescence positive) or stably transformed with NCS-1 compared
to GFP-NCS-1-negative, non-transfected or mock-transfected NG108-15 cells.
7. The number of action potentials that elicited endplate potentials increa
sed in NG108-15 cells stably transformed with rat NCS-1. The mean number of
quanta per impulse (m) increased 5-fold.
8. These results show that NCS-1 functions to facilitate synapse formation,
probably because of the increased quantal content of evoked acetylcholine
release.