J Korean Med Sci.  2012 Oct;27(10):1241-1247. 10.3346/jkms.2012.27.10.1241.

Dendritic eIF4E-binding Protein 1 (eIF4E-BP1) mRNA Is Upregulated by Neuronal Activation

• Moon IS
• Lee HJ
• Park IS

• KMID: 1778833
• DOI: http://doi.org/10.3346/jkms.2012.27.10.1241

Abstract

Long-term synaptic plasticity requires addition of new proteins at the synaptic site. The local protein synthesis at subsynaptic sites confers advantageous mechanisms that would regulate the protein composition in local domains on a moment-by-moment basis. However, our information on the identities of 'dendritic' mRNAs is very limited. In this study we investigated the expression of the protein and mRNA for eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4EBP1) in cultured rat hippocampal neurons. Immunocytochemistry (ICC) showed that 4EBP1 protein is highly localized to the nucleus. In dendrites most 4EBP1 punctae were not colocalized with those of eIF4E. In situ hybridization (ISH) and Fluorescence ISH (FISH) revealed that 4EBP1 mRNA was present in dendrites. The FISH signals formed clusters along dendrites that colocalized with ICC signals for Staufen, a marker for RNA granules. The neuronal activation by KCl (60 mM, 10 min) significantly increased the density of 4EBP1 FISH signals in the nucleus after 2 hr, and both in the nucleus and dendrites after 6 hr. Our results indicate that 4EBP1 and its mRNA are present in dendrites, and the mRNA is upregulated and transported to dendritic domains in RNA granules upon neuronal activation.

Keyword

Dendritic mRNA; eIF4E; 4EBP1; FISH; Hippocampal neuron; Immunocytochemistry; ISH

MeSH Terms

Animals
Carrier Proteins/genetics/*metabolism
Cell Nucleus/metabolism
Cells, Cultured
Dendrites/*metabolism
Hippocampus/cytology/drug effects/*metabolism
Immunohistochemistry
In Situ Hybridization, Fluorescence
Phosphoproteins/genetics/*metabolism
Potassium Chloride/pharmacology
RNA, Messenger/*metabolism
RNA-Binding Proteins/metabolism
Rats
Rats, Sprague-Dawley
Up-Regulation/drug effects
Carrier Proteins
Eif4ebp1 protein, rat
Phosphoproteins
RNA, Messenger
RNA-Binding Proteins
Potassium Chloride