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Drebrin A is a postsynaptic protein that localizes in vivo to the submembranous surface of dendritic sites forming excitatory synapses
Author(s) -
Aoki Chiye,
Sekino Yuko,
Hanamura Kenji,
Fujisawa Sho,
Mahadomrongkul Veeravan,
Ren Yong,
Shirao Tomoaki
Publication year - 2005
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.20449
Subject(s) - synaptogenesis , dendritic spine , excitatory postsynaptic potential , postsynaptic potential , biology , gephyrin , synapse , neuroscience , axon , inhibitory postsynaptic potential , microbiology and biotechnology , receptor , hippocampal formation , biochemistry , glycine , glycine receptor , amino acid
Drebrin A is a neuron‐specific, actin binding protein. Evidence to date is from in vitro studies, consistently supporting the involvement of drebrin A in spinogenesis and synaptogenesis. We sought to determine whether drebrin A arrives at the plasma membrane of neurons, in vivo, in time to orchestrate spinogenesis and synaptogenesis. To this end, a new antibody was used to locate drebrin A in relation to electron microscopically imaged synapses during early postnatal days. Western blotting showed that drebrin A emerges at postnatal day (PNd) 6 and becomes progressively more associated with F‐actin in the pellet fraction. Light microscopy showed high concentrations of drebrin A in the synaptic layers of the hippocampus and cortex. Electron microscopy revealed that drebrin A in these regions is located exclusively in dendrites both neonatally and in adulthood. In adulthood, nearly all of the synaptic drebrin A is within spines forming asymmetric excitatory synapses, verified by γ‐aminobutyric acid (GABA) negativity. At PNd7, patches of drebrin A immunoreactivity were discretely localized to the submembranous surfaces of dendrites forming slight protrusions—protospines. The drebrin A sites exhibited only thin postsynaptic densities and lacked axonal associations or were contacted by axons that contained only a few vesicles. Yet, because of their immunoreactivity to the NR2B subunit of N ‐methyl‐ D ‐aspartate receptors and immunonegativity of axon terminals to GABA, these could be presumed to be nascent, excitatory synapses. Thus, drebrin A may be involved in organizing the dendritic pool of actin for the formation of spines and of axospinous excitatory synapses during early postnatal periods. J. Comp. Neurol. 483:383–402, 2005. © 2005 Wiley‐Liss, Inc.