Dendritic and Postsynaptic Localizations of Glycine Receptor α Subunit mRNAs

Abstract

Some synaptic neurotransmitter receptors, such as those for glycine, have somato-dendritic distributions. Although the machinery for protein synthesis and several mRNAs are present in dendrites and close to synapses in central neurons, so far the mRNAs for neurotransmitter receptors have not been found unequivocally in dendrites. The glycine receptor (GlyR), a ligand-gated channel mediating a chloride-dependent inhibition, is composed of transmembrane ␣ and ␤ subunits. GlyRs are only present at glycinergic postsynaptic differentiation, where they are stabilized by the associated protein gephyrin. With light nonradioactive in situ hybridization (ISH), we observe that GlyR ␣ subunit mRNAs are present in both somata and dendrites of most neurons of the ventral horn of rat spinal cord, whereas the ␤ subunit and gephyrin mRNAs are predominantly in somata. Interestingly, within dendrites GlyR ␣ subunit mRNAs form aggregates that are mostly localized peripherally to the dendritic axial core. Electron microscopic ISH shows that GlyR ␣ subunit mRNAs are associated with postsynaptic differentiations. At these sites, the GlyR ␣ subunit mRNAs are detected in close association with subsynaptic cisternae. This targeting of ␣ subunit mRNAs to postsynaptic domains could provide a means of dynamically modulating synaptic efficacy by changing the composition and the density of receptors at glycinergic synapses.

A Phosphorylated Cytoplasmic Autoantigen, GW182, Associates with a Unique Population of Human mRNAs within Novel Cytoplasmic Speckles

“…It might also be that GW182 is involved in degradation of mRNA but GWBs do not colocalize with the SCF ubiquitin ligase-mediated pathway for protein degradation. Along these lines of discussion, the GWBs described in this study may be related to mRNA-associated particles described in other systems, particularly neuronal cells (Triedge et al, 1991;Miyashiro et al, 1994;Knowles et al, 1996;Martone et al, 1996;Gazzaley et al, 1997;Racca et al, 1997;Bassell et al, 1998;Steward et al, 1998). In oligodendrocytes, injected fluorescent-labeled myelin basic protein mRNA localized to granules that had a radius of 0.6 -0.8 m, contained elongation factors, rRNA and other mRNAs.…”

Synaptic Control of Motoneuronal Excitability

“…In general, transcripts for α 1 -and β-subunits are highly expressed in adult cranial and spinal motoneurons (390, 786, 1081, 1083). α 2 -Transcripts are reduced relative to α 1 (786,1339) but show similar patterns of distribution (1017,1018). Gephyrin transcripts are high in spinal motoneurons (642), whereas α 3 -mRNA is barely detectable in spinal ventral horn and hypoglossal motoneurons (786,1159).…”

Differential Expression of TASK Channels between Horizontal Interneurons and Pyramidal Cells of Rat Hippocampus

“…In particular, it is impossible to harvest dendritic mRNA. It is, however, known that some mRNAs, including some encoding for ion channels, are localized in the dendrites (Crino and Eberwine, 1996;Racca et al, 1997), and it is possible that this is true also for TASK mRNA. Finally, we limited our PCR to 45 cycles to prevent amplification of genomic material.…”