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Synaptic localization of growth‐associated protein 43 in cultured hippocampal neurons during synaptogenesis
Author(s) -
Morita Shoko,
Miyata Seiji
Publication year - 2013
Publication title -
cell biochemistry and function
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.933
H-Index - 61
eISSN - 1099-0844
pISSN - 0263-6484
DOI - 10.1002/cbf.2914
Subject(s) - synaptogenesis , synaptotagmin 1 , synapsin , gap 43 protein , synapsin i , biology , hippocampal formation , synaptophysin , synaptic plasticity , neuroscience , microbiology and biotechnology , synaptotagmin i , synaptic vesicle , immunohistochemistry , biochemistry , immunology , vesicle , receptor , membrane
Growth‐associated protein 43 (GAP‐43), a novel axonal phosphoprotein, is originally identified as a growth‐cone‐specific protein of developing neurons in vitro . The expression of GAP‐43 is also shown to be up‐regulated concomitant with increased synaptic plasticity in the brains in vivo , but how GAP‐43 is concerned with synaptic plasticity is not well understood. In the present study, therefore, we aimed to elucidate subcellular localization of GAP‐43 as culture development of rat hippocampal neurons. Western blotting showed that the expression of GAP‐43 in the cerebral and hippocampal tissues was prominently high at postnatal days 14 and 21 or the active period of synaptogenesis. Double‐labelling immunohistochemistry with an axonal marker Tau revealed that the immunoreactivity of GAP‐43 was seen throughout axons of cultured hippocampal neurons but stronger at axonal puncta of developing neurons than axonal processes. Double‐labelling immunohistochemistry with presynaptic terminal markers of synapsin and synaptotagmin revealed that the immunoreactivity of GAP‐43 was observed mostly at weak synapsin‐ and synaptotagmin‐positive puncta rather than strong ones. The quantitative analysis of immunofluorescent intensity showed a clear inverse correlation between GAP‐43 and either synapsin or synaptotagmin expression. These data indicate that GAP‐43 is highly expressed at immature growing axonal terminals and its expression is decreased along with the maturation of synaptogenesis. Copyright © 2012 John Wiley & Sons, Ltd.