Journal of Neuroscience, Vol 15, 5238-5248, Copyright © 1995 by Society for Neuroscience
A novel RING-H2 motif protein downregulated by axotomy: its characteristic localization at the postsynaptic density of axosomatic synapse
M Nakayama, T Miyake, Y Gahara, O Ohara and T Kitamura
Shionogi Research Laboratories, Shionogi and Co., Ltd., Osaka, Japan.
Axonal injury and its repair are common and basic neuropathological
processes in the CNS, and are composed of a complex of events in a
molecular term. In order to get a comprehensive understanding of these
processes, we isolated several known and unknown genes which were up-or
downregulated in the facial nucleus after transection of the facial nerve
by a subtractive/differential screening. Among them, we focus on one
downregulated gene, named Neurodap1, because this gene encodes a novel
protein carrying the RING-H2 sequence motif categorized in the zinc finger
family. Immunoelectron microscopic analysis revealed that the protein
encoded by Neurodap1, Neurodap1, was distributed mainly on the cytoplasmic
side of the membranes constituting endoplasmic reticulum and Golgi
apparatus, supporting the notion of a previously postulated function of
RING-H2 motif proteins, that is, involvement in the protein sorting
machinery. More interestingly, Neurodap1 was also bound to the postsynaptic
density (PSD) region of axosomatic synapses. This fact suggests that
Neurodap1 is associated with a specific system sorting proteins to PSD.
Therefore, Neurodap1, a newly identified protein as an axotomy-suppressed
gene product, might play a significant role in synaptic communication and
plasticity through the control of the formation of PSD for maintaining
vital functions of nerve cells.