I. Colin et al., GEPHYRIN ACCUMULATES AT SPECIFIC PLASMALEMMA LOCI DURING NEURONAL MATURATION IN-VITRO, Journal of comparative neurology, 374(3), 1996, pp. 467-479
The distribution of glycine receptor (GlyR)-associated gephyrin has be
en investigated in rat spinal cord neurons maintained in vitro by mean
s of immunocytochemical techniques. Gephyrin, which is crucial for the
stabilization of postsynaptic GlyR microdomains, is present in mature
neurons at postsynaptic differentiations. With immunofluorescence, di
scontinous patches of gephyrin were detected within the neuronal soma
of spinal cord neurons on the Ist day after plating. Subsequently, gep
hyrin was present at membrane areas that correspond to points of conta
ct between cells or with the culture dish. By the 5th day, gephyrin wa
s mostly associated with the MAP2-positive somatodendritic compartment
. With immunoelectron microscopy, gephyrin blobs detected at the earli
est stages (1-3 days after plating) were found within the cytoplasm or
associated with the plasma membrane. Asymmetrically immunostained int
ercellular contacts were only detected after 5 days, and gephyrin was
found in association with clearly differentiated postsynaptic membrane
s at 7 days. At later stages, we observed gephyrin immunoreactivity on
ly at some synapses. Our results suggest that gephyrin accumulates ini
tially at the locus of cell-to-cell contacts involved in adhesion proc
esses. These localizations may define hot spots for later accumulation
of the GlyR and possibly other receptors. (C) 1996 Wiley-Liss, Inc.