Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 1997 May 13;94(10):5395-400.
doi: 10.1073/pnas.94.10.5395.

Fragile X mental retardation protein is translated near synapses in response to neurotransmitter activation

I J Weiler  1 , S A Irwin, A Y Klintsova, C M Spencer, A D Brazelton, K Miyashiro, T A Comery, B Patel, J Eberwine, W T Greenough
Affiliations

Fragile X mental retardation protein is translated near synapses in response to neurotransmitter activation

I J Weiler et al. Proc Natl Acad Sci U S A. .

Abstract

Local translation of proteins in distal dendrites is thought to support synaptic structural plasticity. We have previously shown that metabotropic glutamate receptor (mGluR1) stimulation initiates a phosphorylation cascade, triggering rapid association of some mRNAs with translation machinery near synapses, and leading to protein synthesis. To determine the identity of these mRNAs, a cDNA library produced from distal nerve processes was used to screen synaptic polyribosome-associated mRNA. We identified mRNA for the fragile X mental retardation protein (FMRP) in these processes by use of synaptic subcellular fractions, termed synaptoneurosomes. We found that this mRNA associates with translational complexes in synaptoneurosomes within 1-2 min after mGluR1 stimulation of this preparation, and we observed increased expression of FMRP after mGluR1 stimulation. In addition, we found that FMRP is associated with polyribosomal complexes in these fractions. In vivo, we observed FMRP immunoreactivity in spines, dendrites, and somata of the developing rat brain, but not in nuclei or axons. We suggest that rapid production of FMRP near synapses in response to activation may be important for normal maturation of synaptic connections.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Amino acid homologies of FMR1, FXR1 and 2, and the as yet incomplete sequence of clone 8–10b. The consensus sequence for human and mouse FMR1 is taken from Ashley et al. (21). The sequences for FXR1 and FXR2 are from GenBank accession numbers HSU25165 and HSU31501, respectively. Boxes indicate KH and RGG domains of interest; a dotted line indicates either gaps in matching sequences or portions of the 8–10b sequence not yet available.
Figure 2
Figure 2
A representative sucrose gradient-derived dot blot probed with oligonucleotides designed from human FMR1 (nucleotides 118–162) shows that FMR1 mRNA moves into small polyribosomes shortly after mGluR stimulation by 10−2 M DHPG; unstimulated and stimulated aliquots were processed in parallel. Abscissa: dots from serial samples, starting at the top of a 15–45% continuous sucrose gradient. Ordinate: pixel density of dot image, measured on a Fujix BAS 1000 phosphorimager. The original dot images are shown at the base of the figure, along with a tracing of the OD260 polysomal profile.
Figure 3
Figure 3
A polysome gradient dot blot from samples stimulated for 2 or 5 min with 10−5 M quisqualate (in the presence of 4 × 10−3 M CNQX to eliminate the ionotropic glutamate receptor response) was probed with the same oligonucleotide (nucleotides 118–162). Abscissa and ordinate are as in Fig. 2.
Figure 4
Figure 4
Western blot of protein from synaptoneurosomes lysed at indicated intervals (min) after t = 0, either untreated (control) or stimulated by 10−4 M DHPG. (Upper) Staining by anti-FMRP. (Lower) Same blot restained with anti-GFAP.
Figure 5
Figure 5
Quantitative analysis of the densitometric data obtained from Fig. 4, as described. The three bands stained by anti-FMRP were evaluated separately and standardized to the GFAP protein band.
Figure 6
Figure 6
Polyribosome-associated proteins eluted with 0.5 M K+ buffer were separated on an 8% SDS polyacrylamide gel, blotted to nitrocellulose, stained with anti-FMRP, and visualized by enhanced chemiluminescence.
Figure 7
Figure 7
Electron micrographs demonstrating FMRP localization in dendritic spines in cerebral cortex and hippocampus. (a and b) Dendritic spines in s. radiatum of CA1 area of hippocampus. (c) Dendritic spine in the visual cortex containing dark immunoperoxidase precipitate (∗). Presynaptic axonal terminals (A) are not labeled. (d) Unlabeled (—) spine in the visual cortex. Bars = 500 nm.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Steward O, Banker G. Trends Neurosci. 1992;15:180–186. - PubMed
    1. St. Johnston D. Cell. 1995;81:161–170. - PubMed
    1. Steward O, Levy W. J Neurosci. 1982;2:284–291. - PMC - PubMed
    1. Steward O, Falk P. J Neurosci. 1986;6:412–423. - PMC - PubMed
    1. Martone M E, Pollock J A, Jones Y Z, Ellisman M H. J Neurosci. 1996;16:7437–7446. - PMC - PubMed

Publication types

MeSH terms

LinkOut - more resources